David Marze joins the podcast to discuss his journey in building a five-rotor turbocharged engine that aims to replicate the sound of a naturally aspirated V10 Formula One engine. With a background in music, David shares insights on how sound waves influence engine acoustics and the unique challenges of tuning rotary engines. He emphasizes the importance of understanding rotary mechanics to avoid common pitfalls and achieve reliability. The episode blends technical knowledge with personal anecdotes, making it a fascinating exploration of engine sound and performance.
David Mazzei may well have the best-sounding turbocharged rotary on the planet, but how he chased down that elusive F1 V10 sound with this masterpiece of an engine is somewhat unexpected.
Rotary engines are often labelled as temperamental and unreliable, but David Mazzei of Formula Mazzei believes the opposite. In his view, rotaries can be among the most reliable engines when properly understood.
In this episode of Tuned In, David shares his journey from a childhood fascination with technology and cars to becoming a rotary engine expert. He discusses the challenges and rewards of owning and daily-driving his first RX-7.
We dive deep into rotary tuning, starting with the fundamentals—air-fuel ratios, exhaust gas temperatures, and the critical relationship between ignition timing and engine reliability. David also shares his views on engine building, apex seals, and porting, and explains why rotaries deserve a far better reputation than they’ve been given.
We explore the evolution of his five-rotor engine, what it took to bring such an ambitious project to life, and the challenges of building something this complex. David breaks down the science behind its unforgettable sound and reveals how his background in music helped him dial in and replicate the pitch of an F1 V10.
David’s passion for the rotary engine is undeniable. He’s a wealth of knowledge, and what he’s achieved with his MF5 Superlite is nothing short of extraordinary. If you have even a passing interest in rotary engines, this is an episode you don’t want to miss.
0:00 Building The Worlds Best Sounding 5 rotor 4:11 How did you become interested in cars? 17:20 How did daily driving your first RX7 at 17 go? 21:55 Rotary reliability 29:16 How did you learn to tune? 37:24 Can you explain the different rotary engine ports? 40:15 Driveability with modern ECU’s on a bridge port or peripheral port? 46:15 EGT’s on rotary engines 55:15 Air fuel ratios and timing on rotary engines 1:06:05 Can you explain rotary split? 1:12:33 How did the 5 rotor project develop? 1:23:17 Is the turbo charger irrelevant to the sound of the engine? 1:30:30 How do we go about building a 5 rotor? 1:38:23 Billet vs factory cast blocks 1:42:46 What’s your opinion on apex seals? 1:46:25 Should we be running premix in our rotary’s? 1:53:37 How important is injector timing? 1:57:25 Final 3 Questions
"When I got into tuning cars, I really learned that it didn't matter if it was a rotary, but it was always the same thing, right?"
A rotary engine is a different kind of engine that uses a spinning rotor instead of pistons to create power. It's smaller and has fewer parts, but it can be more sensitive to issues like fuel delivery.
A rotary engine, also known as a Wankel engine, is a type of internal combustion engine that uses a triangular rotor instead of pistons to convert pressure into rotating motion. This design allows for a more compact engine with fewer moving parts, but it can be less forgiving in terms of tuning and fuel delivery compared to traditional piston engines.
"And so on a piston engine, you got a little bit of forgiveness there because you can hear a little bit of knock if you lose some fuel pressure and maybe it didn't blow the thing up."
A piston engine is a common type of engine in cars that uses moving pistons to create power. It's the type of engine most people are familiar with.
A piston engine is a type of internal combustion engine that uses pistons to convert pressure from combustion into mechanical energy. It is the most common type of engine found in cars today, providing a balance of power and efficiency.
"And so on a piston engine, you got a little bit of forgiveness there because you can hear a little bit of knock if you lose some fuel pressure and maybe it didn't blow the thing up."
Knock is a sound that happens when the fuel in the engine ignites too early, which can be bad for the engine. It can cause damage if it happens a lot.
Knock, or engine knock, is a term used to describe an abnormal combustion process in an engine, where fuel ignites prematurely in the cylinder. This can lead to engine damage if not addressed, as it creates excessive pressure and heat.
"So if you keep it within the targets on air-fuel ratio timing and temperature and all that, then I think it honestly could be one of the most reliable engines."
The air-fuel ratio tells you how much air is mixed with fuel in an engine. Getting this balance right helps the engine run smoothly and cleanly.
The air-fuel ratio is the ratio of air to fuel in an internal combustion engine's combustion chamber. Maintaining the correct air-fuel ratio is crucial for optimal engine performance, efficiency, and emissions control.
"I think anyone who's followed Formula One really longs for the days of the naturally aspirated V10s. The V12s and the V8s weren't bad either but I've definitely got a soft spot for the V10."
A V10 engine has ten cylinders arranged in a V shape. This setup helps the engine produce a lot of power while staying relatively small.
A V10 engine is a ten-cylinder engine with the cylinders arranged in a V configuration. This design allows for a compact engine size while providing high power output and smooth operation, often found in high-performance vehicles.
"I think anyone who's followed Formula One really longs for the days of the naturally aspirated V10s. The V12s and the V8s weren't bad either but I've definitely got a soft spot for the V10."
Naturally aspirated means the engine gets air from the atmosphere without any extra help from turbochargers or superchargers. This can make the engine sound different and feel more responsive.
Naturally aspirated refers to an engine that relies on atmospheric pressure alone to draw air into the combustion chamber, without the use of a turbocharger or supercharger. This type of engine typically offers a more linear power delivery and a distinct sound.
"There's nothing quite like that sound of a naturally aspirated V10 Formula One engine revving to, I don't know, let's say 18,000 RPM."
RPM means how many times the engine spins around in one minute. Higher numbers usually mean the engine is working harder and can produce more power.
RPM stands for revolutions per minute and is a measure of how many times the engine's crankshaft makes a full rotation every minute. Higher RPMs generally indicate more power but can also lead to increased wear and tear on the engine.
"[68.5s] turbocharged engine. [70.9s] And there's a lot of debate on the internet as to whether or not this thing does actually"
A turbocharged engine is one that has a special device called a turbocharger, which helps it produce more power by pushing extra air into the engine. This makes the car go faster without needing a bigger engine.
A turbocharged engine uses a turbine-driven forced induction system to increase the engine's efficiency and power output by forcing more air into the combustion chamber. This allows for greater performance without significantly increasing engine size.
"[74.9s] sound like a V10 Formula One engine. [76.9s] I'm here to say that at least in my opinion it absolutely does."
A V10 Formula One engine is a powerful engine with ten cylinders that are arranged in a V shape. It's used in Formula One racing cars, which are built for speed and performance.
A V10 Formula One engine is a type of high-performance engine that has ten cylinders arranged in a V configuration. These engines are known for their high power output and are used in Formula One racing, where they are designed to deliver maximum performance and speed.
"...ple all around the world but yeah I wanted to be Maverick, that's my trajectory. I'm going to be a naval f..."
The Ford Maverick is a small pickup truck that is designed to be useful and easy to drive. It's popular because it offers good gas mileage and can carry things in its truck bed without being too big or expensive.
The Ford Maverick is a compact pickup truck that was reintroduced in 2021, aimed at providing a practical and affordable option for consumers. Its significance lies in its versatility, fuel efficiency, and the growing trend of smaller trucks in the automotive market.
"...and I had $5,200 and I bought a Toyota Celica and it was the 1997, 105 horsepower, 7 AFE, 4 banger."
The Toyota Celica is a small car that was made by Toyota. The 1997 version had a 2.2-liter engine that was known for being fun to drive, even though it didn't have a lot of power.
The Toyota Celica is a compact car that was produced by Toyota from 1970 to 2006. The 1997 model featured a 2.2-liter engine that produced 105 horsepower, making it a popular choice among enthusiasts for its sporty design and performance.
"...and it was the 1997, 105 horsepower, 7 AFE, 4 banger. And see you guys had the cool one."
A '4 banger' is a nickname for a car engine that has four cylinders. These engines are usually smaller and help the car use less fuel, but they might not be as fast as bigger engines.
'4 banger' is a colloquial term used to refer to a four-cylinder engine. These engines are typically smaller and lighter, making them more fuel-efficient but often less powerful than larger engines.
"...and it was the 1997, 105 horsepower, 7 AFE, 4 banger. And see you guys had the cool one."
Horsepower is a way to measure how powerful an engine is. The higher the horsepower number, the faster and stronger the car can be.
Horsepower is a unit of measurement used to quantify the power output of an engine. It indicates how much work an engine can perform over time, with higher numbers generally signifying better performance.
The 3S GT engine is a powerful engine used in the sportier version of the Celica. It's designed to give the car more speed and better performance, especially for racing.
The 3S GT engine is a turbocharged four-cylinder engine used in the Toyota Celica GT4. It is known for its performance and was a key component in the car's success in motorsports, particularly in rally racing.
"...we don't have a local automotive manufacturing industry so there's nothing to protect. So we had essentially free access to all of the JDM models."
JDM means cars that are made for Japan. They often have special features that you can't find in cars sold in other countries.
JDM stands for Japanese Domestic Market, referring to vehicles and parts that are produced specifically for the Japanese market. These cars often have unique features and specifications not found in models sold elsewhere.
"...there was so much weight on the front axle line, they just tended to be a big old understeering boat. Sorry to everyone with the Celica that I've just offended."
Understeering is when a car doesn't turn as much as you want it to. It can feel like the car is sliding straight instead of going around a corner.
Understeering occurs when a car turns less than the driver intends, often due to the front tires losing grip. This can make the car feel like it's not responding well to steering inputs, especially in corners.
"...er wing in the back, it kind of looks like a mini Supra. Is that the one we're talking about?"
The Toyota Supra is a fast sports car that many people love for its cool looks and powerful engine. It's famous for being fun to drive and is often modified to go even faster.
The Toyota Supra is a legendary sports car known for its performance and tuning potential, particularly the fifth generation that debuted in 2019. It has a strong following due to its iconic design and capabilities on both the street and racetrack.
"I'm imagining a turbocharger. I'm imagining all this stuff and I got my eyes set on if I sell enough computers..."
A turbocharger helps an engine produce more power by pushing extra air into it. This allows the engine to burn more fuel and go faster.
A turbocharger is a device that forces more air into the engine's combustion chamber, allowing for more fuel to be burned and thus increasing power output. It's commonly used in performance and efficiency applications.
"It also comes in the MR2 and then I could have a turbo engine. So that was my goal."
The Toyota MR2 is a small sports car that has the engine located in the middle, which helps it handle well on the road. It's fun to drive and has been popular for many years.
The Toyota MR2 is a mid-engine sports car that was produced in three generations from 1984 to 2007. It is known for its lightweight design and agile handling, making it a popular choice among driving enthusiasts.
"Maybe I can scrap up enough cash for an RX7, right? Because at this time, you can get an RX7 with about 80,000 miles on it, 1994, 1993 for probably 12 to $15,000..."
The Mazda RX-7 is a sports car that uses a special type of engine called a rotary engine. The models from 1993 and 1994 are popular among car lovers for their speed and handling.
The Mazda RX-7 is a lightweight sports car known for its rotary engine and agile handling. The 1993-1994 models are particularly sought after by enthusiasts for their performance and unique design.
"...I think it was the Fast and the Furious. I think that was the influence primarily for me and my friends where I was located."
'The Fast and the Furious' is a movie series about fast cars and racing. It has inspired many people to get into cars and modify them for better performance.
'The Fast and the Furious' is a popular movie franchise that focuses on street racing, car culture, and heists. It has significantly influenced car enthusiasts and the tuning scene.
"...a buddy that was a few years older than me that got a car before me and he got an Integra. This thing was badass and he was always updating and putting exhaust on it."
The Acura Integra is a small car that many people like because it's fun to drive and can be modified to go faster. It's especially popular among younger drivers who enjoy customizing their cars.
The Acura Integra is a compact car that gained popularity in the 1990s for its sporty performance and tuning potential. It is well-known among car enthusiasts, especially in the import tuning community.
"... anywhere I went, I mean, you could have a stock Maxima and you'd be slapping an exhaust system on the ba..."
The Nissan Maxima is a spacious car that is comfortable and has a sporty feel. It's a good choice for families who want something nice to drive.
The Nissan Maxima is a full-size sedan known for its blend of performance and luxury features, often referred to as a 'four-door sports car.' It has a reputation for reliability and comfort, making it a popular choice for families.
"...popped up on this website, AutoTrader, which is real popular in the US at the time."
AutoTrader is a website where people can buy and sell cars. You can look for different types of cars and see their prices all in one place.
AutoTrader is a popular online marketplace for buying and selling new and used cars. It allows users to search for vehicles based on various criteria, making it easier to find specific models.
"...lines or rats nest, which is the solenoids. It's all this kind of stuff. The vacuum lines for the twin turbos."
Vacuum lines are small tubes in a car that help control different parts of the engine by using air pressure. If these lines break or get damaged, it can cause problems with how the engine runs.
Vacuum lines are tubes that transport vacuum pressure from the engine to various components, such as solenoids and actuators. They play a crucial role in the operation of many engine systems, including turbochargers and emissions controls.
"...The vacuum lines for the twin turbos. My God, that is just an absolute nightmare."
Twin turbos mean there are two turbochargers in the engine, which helps it produce more power. This setup can make the car faster and improve how quickly it responds when you press the gas pedal.
Twin turbos refer to a configuration where two turbochargers are used to increase the engine's power output. This setup can provide better performance and responsiveness compared to a single turbocharger.
"You don't turn the boost up. You don't ask too much from the engine. You don't ever let it overheat."
Boost is a way to make an engine more powerful by forcing more air into it. This helps the engine run better and faster.
Boost refers to the increase in air pressure delivered to the engine's intake, typically achieved through a turbocharger or supercharger. This allows the engine to burn more fuel and produce more power.
"You don't ever let it overheat. You let it warm up and you treat it like any other car the way you should treat any other car."
Overheating happens when an engine gets too hot, which can break it. It's important to keep an eye on the temperature to avoid problems.
Overheating occurs when an engine's temperature exceeds its normal operating range, which can lead to severe damage. It's crucial to monitor engine temperature and ensure proper cooling to prevent this issue.
"Back in that day, I think the most popular option for that generation RX7, the FD was probably the Apexey Power FC."
Apexey is a company that makes special devices to help tune car engines for better performance.
Apexey is a brand known for producing aftermarket engine management systems, including the Power FC, which allows for tuning and optimizing engine performance.
"the only real upgrade was it had the catalyst downpipe, which is like one of the reliability mods because like the pre-catalytic converter would jam up and cause a lot of heat."
The catalytic converter helps clean the air by changing harmful gases from the car's exhaust into less harmful ones. It's an important part for reducing pollution.
A catalytic converter is an emissions control device that reduces harmful pollutants in the exhaust gases of an internal combustion engine. It converts toxic gases into less harmful emissions before they exit the vehicle's exhaust system.
"I pulled the wastegates off or the twin turbos off, import the wastegate because you can't just put a straight exhaust on, you know, a stock rotary or a boost creep."
The wastegate is a part that helps control how much power the turbocharger makes. It makes sure the engine doesn't get too much boost, which could cause problems.
A wastegate is a valve that controls the flow of exhaust gases to the turbocharger, regulating boost pressure. It helps prevent the turbo from producing too much boost, which can damage the engine.
"Nothing. And this is on stock apex seals. And I just followed all the rules and I would j..."
The BYD Seal is a new electric car from China that runs on batteries instead of gas. It's made to be a good option for people looking for an affordable electric vehicle.
The BYD Seal is an electric sedan from the Chinese automaker BYD, designed to compete in the growing electric vehicle market. It showcases advanced technology and aims to provide an affordable yet high-performance electric driving experience.
"...never had that, you know, that hot start problem. Nothing. And this is on stock apex seals. And I just followed all the rules..."
Apex seals are parts in certain car engines that help keep the engine's combustion chamber sealed. They are important for the engine to run well without losing power.
Apex seals are critical components in rotary engines, like those found in Mazda RX-7s. They help create a seal between the rotor and the housing, allowing for efficient combustion and engine performance.
"...ft and right. And then there were these SRT four neons. We called them Skittles."
The Dodge Neon is a small, budget-friendly car that is easy to drive. There was a sportier version called the SRT-4 that people liked for being faster.
The Dodge Neon is a compact car that was produced from 1994 to 2005, known for its affordability and practicality. The sportier SRT-4 version gained popularity among enthusiasts for its performance modifications.
"One, when we're starting to talk about built engines and we'll get deeper into all of this as we go anyway. But when you're talking about built engines, because on face value, they seem like they're relatively simple."
Built engines are engines that have been specially modified to make them more powerful or efficient. People often change parts inside the engine to improve how it works.
Built engines refer to engines that have been modified or constructed with aftermarket parts to enhance performance. This can include changes to components like pistons, rods, and other internal parts to achieve greater power and efficiency.
"...blems that I would see. Like I started with like Mustangs and Corvettes and stuff. I was contract tuning f..."
The Ford Mustang is a classic American car known for being fast and stylish. It's been around for a long time and is loved by many for its powerful engine and sporty look.
The Ford Mustang is an iconic American muscle car that has been in production since 1964, symbolizing freedom and performance. It is significant for its powerful engines, distinctive design, and cultural impact, making it a staple in automotive history.
"...would see. Like I started with like Mustangs and Corvettes and stuff. I was contract tuning for a speed sho..."
The Chevrolet Corvette is a really fast sports car that looks sleek and is built for performance. It's been around for many years and is known for being one of the best American sports cars.
The Chevrolet Corvette is a high-performance sports car that has been a symbol of American automotive engineering since its introduction in 1953. Known for its sleek design and powerful engines, the Corvette is often celebrated for its performance on the racetrack.
"So it was primarily American stuff. But I had a few Miata's, Megascorps, things like that. But it was always the same thing, right?"
The Mazda MX-5, or Miata, is a small sports car that is really fun to drive. It's light and nimble, making it great for people who love driving on winding roads.
The Mazda MX-5, commonly known as the Miata, is a lightweight two-seater sports car that has been praised for its handling and driving enjoyment since its launch in 1989. Its significance comes from its affordability and the fun driving experience it offers.
"Fuel pump wasn't wired correctly. It burns out the pins for the tank hat wiring or relay doesn't give enough juice"
The fuel pump helps move fuel from the tank to the engine. If it doesn't work right, the engine might not get the fuel it needs to run properly.
A fuel pump is a critical component in a vehicle's fuel system that pumps gasoline from the fuel tank to the engine. If it's not wired correctly, it can lead to engine performance issues or failure to start.
"I had to take that car and have it dyno tuned and it was on an AEM version 2 ECU."
Dyno tuning is when a car's engine is tested on a special machine to see how much power it makes. This helps to make adjustments so the engine runs better.
Dyno tuning refers to the process of using a dynamometer to measure the power output of an engine and adjust its performance parameters for optimal efficiency and power. This is crucial for ensuring that the engine runs smoothly and meets performance expectations.
"... think it was an R100. He also had a three rotor RX8. R100, yeah."
The Mazda RX-8 is a sporty car that uses a special type of engine called a rotary engine, which makes it different from most cars. It's known for being fun to drive and has a cool design.
The Mazda RX-8 is a unique sports car produced from 2003 to 2012, featuring a rotary engine that offers a different driving experience compared to traditional piston engines. It is appreciated for its handling and distinctive design.
"...re getting basically absolute garbage out of your lambda sensor. So I've always thought it's a case of un..."
The Lancia Lambda is an old car from the 1920s that was special because it had some new ideas in how cars were built. It's important in car history for being innovative.
The Lancia Lambda is a historic car produced in the 1920s, notable for its innovative engineering and design, including a unibody construction. It is significant in automotive history for its role in advancing automotive technology.
"...ous to say that like a four rotor would be like a s2000 engine at double the rpms okay and then that's s..."
The Honda S2000 is a small sports car that is known for being very fun to drive. It has a powerful engine that can go really fast and is loved by car fans.
The Honda S2000 is a two-seat roadster that was produced from 1999 to 2009, celebrated for its high-revving engine and precise handling. It has become a classic among enthusiasts for its engaging driving experience and reliability.
"...es they like overlap one another so like a dodge viper for example that's why it doesn't sound like a r..."
The Dodge Viper is a super fast sports car with a big engine that makes it really powerful. It's known for its unique look and is loved by car enthusiasts.
The Dodge Viper is a high-performance sports car known for its powerful V10 engine and distinctive styling, produced from 1992 to 2017. It has a cult following due to its raw performance and the driving experience it offers.
"... a few key cars that do have that sound like the lexus lfa that you know is remarkable sound quality and so ..."
The Lexus LFA is a super fancy sports car that is very fast and has a unique engine sound. It's a rare car that many people admire for its design and performance.
The Lexus LFA is a limited-production supercar known for its exceptional performance and unique sound, produced from 2010 to 2012. It represents Lexus's foray into high-performance vehicles, combining luxury with cutting-edge technology.
"as soon as you introduce a turbocharger into the system kind of all bets are off so is th..."
The Dodge Charger is a big car that looks tough and can go really fast. It's popular because it has a lot of space inside and is fun to drive.
The Dodge Charger is a full-size sedan known for its muscular design and powerful engine options, often associated with American muscle car culture. It combines practicality with performance, making it a popular choice for those seeking a sporty yet functional vehicle.
Building The Worlds Best Sounding 5 rotor
How did you become interested in cars?
How did daily driving your first RX7 at 17 go?
Rotary reliability
How did you learn to tune?
Can you explain the different rotary engine ports?
Driveability with modern ECU’s on a bridge port or peripheral port?
EGT’s on rotary engines
Air fuel ratios and timing on rotary engines
Can you explain rotary split?
How did the 5 rotor project develop?
Is the turbo charger irrelevant to the sound of the engine?
How do we go about building a 5 rotor?
Billet vs factory cast blocks
What’s your opinion on apex seals?
Should we be running premix in our rotary’s?
How important is injector timing?
Final 3 Questions
Select text to request an explanation
When I got into tuning cars, I really learned that it didn't matter if it was a rotary,
but it was always the same thing, right?
And you've probably seen it, fuel pump wasn't wired correctly and bore, you know, the ignition
system isn't set up.
And so on a piston engine, you got a little bit of forgiveness there because you can hear
a little bit of knock if you lose some fuel pressure and maybe it didn't blow the thing
up.
The rotary engine, you don't get that forgiveness.
So if you keep it within the targets on air-fuel ratio timing and temperature and all that,
then I think it honestly could be one of the most reliable engines.
Welcome to the HPA TuneIn podcast, I'm Andre your host and in this episode we're joined
by David Marze from Marze Formula.
I think anyone who's followed Formula One really longs for the days of the naturally
aspirated V10s.
The V12s and the V8s weren't bad either but I've definitely got a soft spot for the V10.
There's nothing quite like that sound of a naturally aspirated V10 Formula One engine
revving to, I don't know, let's say 18,000 RPM.
Well actually there could be one thing that's very similar and that is David's five rotor
turbocharged engine.
And there's a lot of debate on the internet as to whether or not this thing does actually
sound like a V10 Formula One engine.
I'm here to say that at least in my opinion it absolutely does.
Now we dive into David's background where he's actually been brought up and trained as
a musician and that might seem like a little bit removed from developing a five rotor
turbocharged rotary engine but there are actually some crossovers here which David
dives into in this episode about the sort of effects on the sound waves and how you
can use that knowledge to your favour to actually change the sound that your engine
makes and he's worked really hard to develop this and try and chase down that elusive
V10 F1 sound.
Again I think he's done an amazing job.
Rotary engines have a bit of a bad reputation and I think somewhat unjust as well.
A lot of the problems with rotary engines come down to people who don't understand how
to build them, they think that they're simple so they can chuck one together with insufficient
knowledge in their back shed.
And it also comes down to rotary engine tuners who have come from a piston engine tuning
background and try and apply the same tuning techniques that work on a piston engine to
a rotary engine and the results are lots of needlessly broken engines.
We find out from David about his own philosophy on both building and tuning an engine
that's going to last the test of time.
Before we jump into our chat, for those who are new to the TuneIn podcast, high performance
academy is an online training school.
We specialize in teaching people how to build performance engines, how to tune EFI, how
to construct wiring harnesses.
We also cover topics on fabrication, 3D modelling and CAD, race driver education and data logging
just to name a few.
You can find all of our courses at hpacademy.com forward slash courses.
All of these courses are delivered in high definition video modules that you can watch
from anywhere in the world provided you've got an internet connection.
This means you can learn from the comfort of your own place and you can learn at your
own pace.
All of our courses also come with a 60 day, no questions asked, money back guarantee.
So if you purchase them for any reason at all, decide it wasn't quite what you expected,
no problem, let us know, we'll give you a full refund.
And for podcast listeners, you can also use the coupon code podcast75 that will get you
$75 off the purchase of your very first HPA course.
We'll put the coupon code in the show notes to make it nice and easy for you to find.
Lastly, if you like free stuff, then I've got a great deal for you.
We are constantly partnering with some of the biggest names in the aftermarket performance
industry to give away some great prizes.
You can always find our latest prize at hpacademy.com forward slash giveaway.
It might be an aftermarket ECU or dash, it could be some engine components or engine
building tools or just about anything in between.
They are great prizes and we will ship them free of charge to your door if you're the winner.
There's no tricks here, no purchase required to get your name into the draw.
Alright enough with our introduction, let's get into our interview now.
Alright welcome to the podcast, David thanks for joining us today.
This is one that I'm definitely excited for.
As always, let's start by finding out a little bit about your background and specifically
how you got interested in cars.
Yes sir, thanks for having me.
I really appreciate you inviting me to this podcast.
It's one of my favorites, I love how technical you get and how educational and professional
your videos are and it's a real treat to be here and just have the opportunity to talk with you.
So thanks for having me on here.
I appreciate it.
So my name is David Matze and I was born in Virginia and in Virginia I lived near a naval base
or naval shipyard where they built all the nuclear submarines and aircraft carriers
and of course there was Langley Air Force Base that was near there.
So when I was a kid I was exposed to all these cool things like fighter jets
and I got to go to the Space and Rocket Museum and so when I was four or five years old
that was my whole life, I want to be a fighter pilot, I was obsessed with airplanes
and all military tech and so I was always playing with my Legos
and I was in my own little world just dreaming about kind of stuff and so...
I went down a very similar path after Topgarden the movie, the first one came out
probably showing my age a little bit but much like probably thousands, tens of thousands of people
all around the world but yeah I wanted to be Maverick, that's my trajectory.
I'm going to be a naval fighter pilot flying an F-14 Tomcat.
Although I do have my pilot's license so I guess I got a little way towards that dream.
Do you really? That's awesome, what do you fly?
Just a little Cessna 172, I just do it for fun.
Yeah but we live in a beautiful part of the world and seeing it fly in Queenstown
and the surrounds are amazing so I really love flying.
Wow, that's really cool.
But I digress, let's get back to your story.
Yeah sure, I love it, that's awesome and so way into that same stuff just like you
I was born in 89 so I grew up in the early 90s and my father had an appraisal company out of the house
and so he had a bunch of different computers and people that would come over and work
and so I was exposed to computers too, pretty young age then which it wasn't common to have computers at home.
People were just now starting to get computers at that time and we had America online and the dial up
and so I was tinkering with the computer and learning MS-DOS and all that when I was 5, 6 years old
and so I think that's a big part of this because that allowed me to kind of get a jump on how to have access to information
and so I was able to learn real quickly by using the internet and specifically at those times growing up like the forums
and then I was also into music, I played my trumpet a lot.
I have friends but I always loved to just be in my own world so it was always music and cars
and I loved anything with gasoline, I loved the smell and the engines
so the lawn mower guy would come cut the grass at our house and I would follow him around with my toy lawn mower
because I just loved the sound and the smell of the engine, I always wanted to know how that stuff works.
So I guess when I got older we moved to Alabama which is where I live now, Southern state
and here at the time it was primarily like trucks and just a whole different kind of thing, hunting
and there wasn't a lot of race car stuff here but although we have the Barbara Motorsports Museum
it's a beautiful place now where they have the indie races and stuff.
You know, I was just kind of in my own world here trying to fit in and I just really dove into the computer stuff
I started building my own computers and I would learn on the forums.
That's how I would learn about different parts like motherboards and processors
and I just loved like dreaming about it.
So I always had this little dream was I'm going to build my own computer
and I just loved how cool it was that you could overclock and you could get liquid cooler for your processor
and you see like this is real similar to cars, right?
Because cars you can modify and you can find out what's going to happen
and you want to try this and you want to try that and you want another pound of boost
and so it was like the same kind of thing.
So I went from computers and that's how I would make money.
I would repair people's computers that go around the neighborhoods and run a newsletter
and I had a little company called Monster Box.
So that's how I saved my money to get my first car and my parents helped me a little bit.
They sold an old car that we had when I was born and I had $5,200 and I bought a Toyota Celica
and it was the 1997, 105 horsepower, 7 AFE, 4 banger.
And see you guys had the cool one.
You had the GT4 that had the 3S GT engine.
I think New Zealand had that and Japan, right?
No, we were pretty lucky and still are that we don't have a local automotive manufacturing industry
so there's nothing to protect.
So we had essentially free access to all of the JDM models.
So yeah, the ST185 and ST205 Celica GT4s, actually was that maybe a later era.
Can't quite remember but yeah, must admit I was never actually a massive fan.
I spent a bit of time driving an ST205 and I found like they were just so big and heavy
and I think because there was so much weight on the front axle line,
they just tended to be a big old understeering boat.
Sorry to everyone with the Celica that I've just offended.
You killed my dream.
Yeah, so I never got to see one of those.
They've never seen one to this day.
The one that has like the higher wing in the back, it kind of looks like a mini Supra.
Is that the one we're talking about?
Yeah, so that was it, man.
I always like, I would drive this little car around and the key here is that it's about dreaming, right?
So I didn't know this at the time but it's kind of my philosophy now is that there's like constructive daydreams.
Dreaming is what I call it.
So I drive my Celica around and it's got 100 horsepower and all the kids at school have Supras and bad-ass stuff.
I've just got this little four-banger but it's a five-speed and so I'm imagining boost noises.
I'm imagining a turbocharger.
I'm imagining all this stuff and I got my eyes set on if I sell enough computers and teach enough trumpet lessons,
I can buy a 3S GT engine because at the time you could get these front clips from eBay
and I could get the whole front end to one of those cars from Japan and I could swap a 3S GT.
It also comes in the MR2 and then I could have a turbo engine.
So that was my goal.
Well, I got rear-ended and the car was totaled and so that killed my dream, right?
So I just started looking and I'm hoping, I wonder what's going to happen with the insurance, right?
Well, I got super lucky.
It's just a miracle.
And I think this is because I had such big dreams that it was just the universe intervening
but I got almost double the money that I paid for the car from insurance.
It's almost unheard of.
Yeah, I've got like 10 grand.
Insurance in my experience is always a very one-way street and it's only ever the insurance companies that profit out of it.
But congratulations, it's great.
So it's like a one in a million chance there.
Yeah, so now I've got some cash and I'm saving up some money.
I'm going to ride the bus to school for the rest of this year.
Maybe I can scrap up enough cash for an RX7, right?
Because at this time, you can get an RX7 with about 80,000 miles on it, 1994, 1993 for probably 12 to $15,000 and way different than it is today, right?
Yeah, look at the process now.
Yeah.
Yeah, sometimes I think back in that era, if only you had a crystal ball and you knew what the prices of the JDM hero cars were going to do.
You could have done very well out of it, but none of us did.
Yeah, it's like $12,000 for a freakin' Re-Man Mazda engine now, right?
Just the motor, if you're lucky.
I'll just stop you there.
First of all, I find when I'm interviewing anyone from the US, it's always interesting when they've gravitated towards Japanese domestic market versus USDM.
And then second part of this question is, what is it about the Rotaries or RX7s that attracted you?
Because I kind of find people are very divided into piston and rotary.
That is true.
Well, I didn't really have a lot of experience with either at the time.
So I was just kind of going on intuition or instinct or whatever you want to call it.
And I think it was the Fast and the Furious.
I think that was the influence primarily for me and my friends where I was located.
Because I had a buddy that was a few years older than me that got a car before me and he got an Integra.
And this thing was badass and he was always updating and putting exhaust on it.
This is before I had my license.
He takes me to see the Fast and the Furious and what's in the movie.
Well, Vin Diesel is driving an RX7 and there's all these badass eclipse and the Supra.
And I think that's what it was, man.
It was like a whole other spin.
And we were here in America, so there's all muscle cars, right?
That's primarily the American history.
But that movie just kicked it off for the Japanese market here, for the JDM stuff.
And so everyone at my school, pretty much everybody that I knew anywhere I went,
I mean, you could have a stock Maxima and you'd be slapping an exhaust system on the back of it, underglow.
And it was just crazy.
It's not like it is today.
It was like a household thing.
Everybody was modifying their cars.
And so I'm like, I got to get into this.
And nobody had RX7s.
And they were like pretty good deal.
I really wanted a Supra, but couldn't afford that one.
That's like $30,000, $40,000 back then.
But an RX7, well, it could be possible.
However, I didn't realize the reason that they were a good deal is because they come with a lot of requirements.
You have to know your stuff.
And there's not a lot of people that work on them.
So that was something I was not quite aware of until I started digging into it.
But some of that was the appeal as well.
It's like the experiment aspect of doing something that you don't like that nobody else has and that you don't you have uncertainty with uncertainty comes reward.
If you're willing to persevere.
So I'd never even seen an RX7.
I didn't know anyone that had one.
That's how rare they were around here.
There's only a few guys in the area.
And so one of them popped up on this website, AutoTrader, which is real popular in the US at the time.
And it was in Ohio, which is about 10 hours away.
And so I go tell, well, my parents are really cool.
They could be really strict, but at the same time, they would allow you to argue your case.
So if they disagreed with something, they'd still allow you to present a case.
And a lot of times they would still say no.
But if you were, if you really had a good case, maybe they would allow you to do it.
So I prepare all this documentation, like I'm on the forums researching RX7s.
I'm learning about, you know, compression tests and the coolant test, the air separation tank, all these things.
And who would be potential people I could link up with that could help me fix it.
I've got this whole case because I know they're probably going to say, oh, this is totally not a good idea for you to spend all your money on.
So I go to them and it's like a document.
Okay. And I tell my dad, I'm like, I want to get this RX7, you know, and I've got $13,000 saved up and I can do this.
I got another thousand in the bank in case I need to fix it.
What age are you at this point?
I'm 17.
That is truly impressive.
Good job.
So I go to him and I'm like, I got this whole plan, right?
And I'm thinking this is going to work out.
And his response is like, basically, this is a bad idea.
Like you don't need to be doing this shit.
Like first of all, it's a turbo car, which means with a turbocharger comes complication and issues.
And he's not a mechanic.
Okay. But he's a smart guy.
So I give him that.
That makes sense.
And then he also says, well, it's a rotary engine and who the hell knows how to work on those.
So, you know, you're going to be driving to and from school.
And then you, you know, if you go to college, you're going to need a car that's reliable.
I mean, what are you doing?
Like this, that's why this thing is a good deal.
I can't, I can't argue with any of those points.
Let's, let's be honest.
The man, the man is making good sense.
He's absolutely correct, right?
But I was hard headed in my ambition and I had so much love for this.
It just had to be this.
I can't explain it.
I just, I had to have it.
And so I was just like, I got to have this thing.
I got to drive this car.
I accept all consequences that come with this.
I accept all the responsibility.
And if I got to walk to school and if I got to sell this thing for half price and go back
and get another Celica, then I'll do whatever I got to do.
And it was one of those things where, you know, when someone tells you like they're not mad,
but they're disappointed, it's like that kind of response.
It was like, okay, well, have it your way.
So you won that battle.
That's what's important though is because at that moment it really put me in that like
sense of, okay, I better be responsible because my parents aren't going to bail me out of this.
And I better take this seriously.
I better not blow this thing up.
I better learn everything I can.
It was like a challenge to prove to them that I was, you know, going to figure my shit out.
And then it was a challenge to myself to figure it out.
Yeah.
So that was it.
Well, let's dive into the experience.
What did the reliability prove to be like?
Was it exactly what I'd expect or did it actually prove to be perfectly reliable?
Both.
Both.
It had some things that would pop up, but anything that popped up was never rotary related.
And to this day, I've never really had any issues that were rotary related.
It's always been other things.
And I found that it was mainly the supporting things on the car.
Like it would be like the radiator in tanks because they were plastic would crack or it
be the air separation tank that was plastic and it would crack or you'd have a vacuum
lines or rats nest, which is the solenoids.
It's all this kind of stuff.
The vacuum lines for the twin turbos.
My God, that is just an absolute nightmare.
And they just cook with the heat in that engine bay.
Must have done 50, 60, 80,000 miles.
Everything's falling apart and trying to figure out how that all goes.
Obviously, factory documentation will tell you.
But yeah, it's a drama.
Yeah, you drink from a fire hose of knowledge when you're trying to figure out all this on
the rotary stuff.
There's so much information that when you're a kid and I wasn't a mechanic.
I mean, I was just working out of my parents' garage in their house.
I'd go to Walmart and get the handjack and some tools and just go at it.
But the forums were my best friend.
The forums is how I learned everything.
I learned that if you ask good questions and you answer other people's questions, then
people take you seriously.
You kind of build a reputation and that's how you exchange information.
And it was just a wonderful thing to have the access that way.
I mean, today, the internet's awesome to you.
But I feel like the forums are always, and you have your own forums, right?
I believe, is that correct?
Yeah, we do.
Yeah.
So that's just, it's such a great way to, you know, I would read people's build threads
and that's how I kept it running.
And so anytime anything would break, you know, initially I'd be real frustrated.
Oh, this thing broke again or this broke again.
But it was like a win every time because it was never rotary related.
And then I started to learn, I'm like, okay, eventually this is going to become reliable.
And I got to the point where I daily drove it for four years.
Wow, that's amazing.
And I even daily drove it to college.
And so the key was to not be greedy.
You know, you don't turn the boost up.
You don't ask too much from the engine.
You don't ever let it overheat.
You let it warm up and you treat it like any other car the way you should treat any other car.
And man, I mean, I had a thing up to like 300, maybe 330 horsepower.
It was the sequential twins.
And I was running this thing called the Peter Pharrell purple box, which people said was a terrible piggyback computer.
It worked great.
I don't know if you ever heard of that, the purple box.
No, I've never heard of that one.
Yeah.
Back in that day, I think the most popular option for that generation RX7, the FD was probably the Apexey Power FC.
You know, a number of cars that would also come into New Zealand from Japan already with the Power FC installed.
That was probably the main go-to.
So a couple of things here.
During that four year period, you've just mentioned about this box and the 330 horsepower, which is great.
During the four years, what was the car modified in terms of power levels or was it stock at that point?
Well, stock would have been closer to 250 crank.
So it came with the stock twins and it had, I think the only real upgrade was it had the catalyst downpipe,
which is like one of the reliability mods because like the pre-catalytic converter would jam up and cause a lot of heat.
So that was pretty much like the only thing and the engine had like 80,000 miles on it.
So what I did was I just slowly upgraded everything that would potentially increase the reliability.
So I put like a full exhaust on and get rid of the catalytic converter.
And then I pulled the wastegates off or the twin turbos off, import the wastegate because you can't just put a straight exhaust on, you know, a stock rotary or a boost creep.
So I learned of like how wastegates work by doing that, right?
So everything that I'm doing, I'm learning so much from all of it and, you know, upgrade the secondary injectors and this computer could handle that.
I believe that's something I did.
I can't remember.
Maybe that was on another engine that I had.
But essentially it was stock twins.
And I'd redid all the vacuum lines with the silicone hoses, put a stock mount intercooler that's, you know, aluminum with aluminum piping and Coyo inflow radiator.
And yeah, and it was just, it was great.
So basically supporting mods?
Yeah, supporting mods.
And the thing ran beautifully, man.
For so many years, never had an issue, never had a starting issue, never had that, you know, that hot start problem.
Nothing.
And this is on stock apex seals.
And I just followed all the rules and I would just, I really respected the car and I think that's why it did me well.
And it was funny because I had all these friends.
I mean, we used to go to these street races that, you know, people don't talk about, but there used to be these big street races downtown at night.
And when I'd go out there and watch, but I'd always be real careful.
And my friends would have these Subaru's and they'd blow their engines left and right.
And then there were these SRT four neons.
We called them Skittles.
I don't know why we called them Skittles, but they, everybody's run like 40 pounds of boost on those things and they're lifting heads.
And it's like, how about that?
Yeah.
Right.
So I outlived everybody because I just, and I'm the rotary guy who's supposed to, you know, boost goes in apex seals comes out and that just gave me confidence.
I'm like, well, maybe this thing can be really reliable.
If you just fix all the junk around it, that just was, you know, cutting corners on Mazda's part to meet the budget, you know, so you just give it what it needs.
It lives.
I think my personal stance on this has always been that the rotaries get a bad reputation for a liability for a couple of reasons.
One, when we're starting to talk about built engines and we'll get deeper into all of this as we go anyway.
But when you're talking about built engines, because on face value, they seem like they're relatively simple.
There's no valves, valve springs, cams, et cetera.
Not as many moving parts.
So it seems on face value like it's an easy one to build one of these in your home shed.
And don't get me wrong, obviously that can be done, but like anything, it requires attention to detail and the correct amount of knowledge.
And I think you get a lot of people putting these together without either of those things.
Maybe your shed's near the beach and the sand blowing in the door, whatever.
So you're setting yourself up for failure with an engine that hasn't been assembled correctly.
And then the other knock on effect of this is tuners who aren't experienced in rotary engines
and try tuning the rotary engine like a piston engine and they need to be dealt with carefully.
And I remember back when I was running my old shop, you'd get guys booking a rotary for a tune
and they look like they just lost their grandmother as they're unloading the car off the trailer
because they're already expecting, before the things even bolted to the dyno,
they're already expecting that it's going to be broken.
That was just how it went.
So yeah, I think you're absolutely right.
I mean, you treat them correctly, tune them carefully, get them built properly,
and they can actually be reliable.
Yeah, 100%. It's weird. I have not really had a rotary related issue.
I mean, I had an issue that was rotary related, but it was due to the engine not being built correctly,
which is exactly what you said.
But when I got into tuning cars, which we'll get to that later, but just real quick,
when I got into tuning cars, I really learned that it didn't matter if it was a rotary.
This is the same kind of problems that I would see.
Like I started with like Mustangs and Corvettes and stuff.
I was contract tuning for a speed shop here.
So it was primarily American stuff.
But I had a few Miata's, Megascorps, things like that.
But it was always the same thing, right?
And you've probably seen it.
Fuel pump wasn't wired correctly.
It burns out the pins for the tank hat wiring or relay doesn't give enough juice
or the ignition system isn't set up or a crank sensor.
It's always like that kind of stuff, right?
And so on a piston engine, you got a little bit of forgiveness there
because you can hear a little bit of knock if you lose some fuel pressure
and maybe it didn't blow the thing up.
The rotary engine, you don't get that forgiveness.
So if you keep it within the targets on air fuel ratio timing
and yada yada and temperature and all that,
then I think it honestly could be one of the most reliable engines.
It's just that the fact that it's inefficient is why it was probably discontinued
and the fact that didn't have competition in the marketplace.
Not a lot of people picked it up.
So Mazda was only able to go so far with it because of the budgets that they had.
And if you imagine that if all companies were competing on the rotary platform
then it could have been one of the greatest engines ever.
So I think it's just my philosophy on it is treat it like it's any other engine.
And if you're tuning a 4G motor or you're tuning a 3S or 2JZ,
like you should have the same philosophy.
They try not to knock the motor.
I mean, right?
And then I think you'll be rewarded with a rotary.
So now again, I'm not a race car driver.
I'm not pushing these cars for competition.
So I can't really comment on that aspect.
But obviously Mazda figured it out with their racing series
because there's the Patrick Dempsey cars that were racing those three rotors.
The Riley Motorsports cars are super reliable.
And same thing with the 787B program.
Obviously those cars had different supporting characteristics.
But when they really buckled down and put all the engineering into them,
they proved to be extremely reliable.
I mean, those 24-hour cars with the ceramic apex seals
continue to run many years after the events
because the apex seal wear was real slight.
I mean, I've heard when they tear those engines down,
the engines still look really nice.
They just refresh them.
I think your point you made there is really valid there.
The rotary engine, the tuning approach is very similar to Piston,
but the tuning envelope, the window for keeping a rotary engine alive
just becomes much narrower.
And yeah, you can run a Piston engine into light detonation.
It's obviously not something we try to do, but you can do that
and it's going to live through it.
Whereas a rotary engine, you're probably not going to be that lucky.
Yes, agreed. 100%.
You don't get that margin of error, so you've got to be real careful.
So it's tighter margin.
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Alright, let's get back to the episode.
Just talking about sort of your trajectory here
because you mentioned the tuning side of things.
I'm really interested to dig into how you started to develop those skills.
I mean, essentially the reason that we are here talking to you today
and the reason that High Performance Academy exists
is because I created the resource that I would have loved to have access to
when I was trying to learn how to tune and I had to do it the hard way by trial and error.
So yeah, just talk us through that.
Yeah, certainly.
So I went to school for music after high school.
I went to college to learn music.
I ended up getting a major in music and business so that I have a fallback.
That was my original goal was to be a trumpet player, an orchestra player.
But I just didn't love it enough.
So you have to really love something more than just doing it.
You have to love the day in, day out of that.
And the thing I really loved was cars.
So I would use my real estate, became a commercial appraiser.
And I would use my real estate job, which is what I do now,
to be able to fund my side quest, which is the rotary stuff.
And I didn't have my mindset on the rotary stuff as like this is going to be my career.
So I always did it as like a passion thing, but I just really loved it.
So that motivation led me to a bunch of different places with it.
And so when I finally got out of school and I still had the RX-7,
I always wanted to do a single turbo.
But I knew, okay, I need to live within my means until I could afford it.
But I'm still doing that constructive dreaming.
So I'd pace back and forth in my apartment at school and I'd do spreadsheets
and I'd read and research about all the things required to do a single turbo.
So that by the time I graduated and I had the money to do it,
I already knew exactly what deal to take whenever I saw it.
And so I found an engine swap that could essentially be put right in place.
Like it came with the turbo, the ECU, like all of it and the motor.
So that's when I really started to get serious and I swapped the engine
and it was up and running in about 48 hours.
Really cool to be able to pull that off and it was a good deal.
It came from a guy that built the proper setup and he was moving on to an LS platform.
So that's when I started learning a little bit about tuning
because I had to take that car and have it dyno tuned and it was on an AEM version 2 ECU.
So that was the first time having a standalone is that's when I started to see the interface of the laptop stuff
and I can look at his map and see what timing is doing and air fuel and all of that.
And so fast forward from there, I wasn't the tuner but I witnessed it happening.
So I started to understand air fuel ratios and timing and I'm here in the lingo
and starting to get a little bit of, I bought a wideband, a Zetronix
and so I would always track the air fuel because I want to be careful.
So now I'm making like 500 horsepower on pump gas and I'm using methanol injection.
So now we're really flirting with that edge, right? It's like 22, 23 PSI
and that's the territory where if it's not dialed in, you're going to knock and hurt the motor.
And again, it was reliable. I mean, I made 500 plus for years on that
and then what I did was I ended up selling the old setup that I had that was my high school setup
to be able to afford to do the current setup, which was the single turbo
and then I had enough money saved up to do a three rotor.
I'm like, okay, this stuff is just, it's challenging but I love it enough that I seem to be succeeding.
So let me try again. So then I sold that motor and I purchased a three rotor
and that's when I really had to start buckling down and figure out what's going on
and that's when I started dabbling tuning myself because there was a guy that tuned that project for me originally
but I had to do some touch up stuff because it attunes like never 100%.
The dyno doesn't necessarily match the real world and when you're dealing with a rotary engine
and conditions change and things like that, you might need to make adjustments.
So I'm like, maybe I need to add a little bit more fuel here or maybe I need it.
It's got a little hesitation. Let me play with the accelerator pump settings
and so that's when I started getting more comfortable with it
but I still wasn't confident enough to be doing my own mapping.
Then the same thing again, I sold the whole car and wanted to do a four rotor project.
So I sold that whole car, ended up coming way off on top.
Again, like made a lot of money on it, which is like one in a million chance.
I'm thinking, okay, if I'm doing this well with this thing and I'm making profitability
then why not just take the uncertainty again, just go again.
You know, I'm young while I can risk it.
So then I did a four rotor setup and I built a whole another car with that
and this is the first time that I experienced doing all the wiring and outsourced the harness
but I'm understanding inputs and outputs and understanding all the different sensors
and the four rotors, you're really, there's so much you have to learn now
because doing a four rotor is not just a straightforward process.
It's kind of like everybody has their own process to how you're going to achieve that.
Now, I know it's possible to do a four rotor because seeing other people do it
but doing it correctly is kind of subjective.
And so that car ended up with a lot of, had a lot of challenges
and I learned a lot because we had to rebuild the engine
and we had to redesign the exhaust manifold twice and the intake design
and a whole lot of stuff that we had to redo.
And in doing that, I learned enough to where I was like, okay, I can do this myself.
I can tune this myself.
And so there was a gentleman that tuned it for me initially in California
and he did a great job.
His name was Abel Ebarra.
He's a world record NHRA drag racer.
He had a sort of RX2 or an R100 that was really famous.
So that was the Canadian Focus one, wasn't it?
Yeah, I think it was an R100.
He also had a three rotor RX8.
R100, yeah.
No, I remember.
He had a three rotor RX8 that was like record too.
So he did a really good job on the car but the drivability just suffered
and I can't blame him for that.
It's just really hard to get a peripheral port to be a drivable vehicle.
And so when I got the car back to Birmingham,
I just wasn't happy with the accelerator enrichment settings
and some of these kind of things.
I wanted it to be smoother.
So weird is some of my friends were working at this performance shop
that was like doing Mustangs and cars like that and they had a dyno
and the dyno tuner, the guy that worked for them ended up quitting.
And so they were in a gym and they didn't have anybody to tune their cars
and they were looking for a tuner.
And they were like, do you want to just like try to hold us over
for like the next few weeks?
Here's some books.
I'm like, shit.
Kind of what you said, like if you can tune a rotary, well, then you probably
can tune a piston engine.
I'm like, okay, I know a little bit about like, I know my way around the Haltech.
You know, I understand that the concepts, I just haven't physically done it.
But if I can do the standalone stuff that dabble with it,
then I can at least handle HP tuners, a flash tune on Mustang, you know,
because there's more forgiveness.
So I tuned like a bunch of cars and I ended up not being there two weeks,
but like a year plus.
And so I had a lot of experience with a bunch of different piston engines
and that's when I discovered all the things that we were talking about with everybody
that comes in and they're like, oh, yeah, this thing's ready to go.
I'm like, no, it's not.
The fuel pressure dropped.
So, all right, I'm going to stop you there, David, because we've got at the
moment about a million follow up questions that I want to ask.
So if we come back one step, and this is not really tuning related,
you're just talking about the four rotor and peripheral ports.
Actually, let's come back one step and just talk about the typical porting options
that we see on rotary engines.
So typically we've got a side port that's relatively mild in a stock engine
and there's extend ports, bridge ports, and then the holy grail is we go straight
through the rotor housing with our peripheral port.
Can you give us a quick rundown on, I guess, pros and cons of each
in terms of power, tuneability, and drivability?
Yeah, so the side port is going to be most similar to the factory.
When they say side port, it's generally like a street port.
People talk about a street port.
It's just a larger porting of the side port.
You're extending the intake duration by opening up the size of that.
And that's going to give you a little bit more power.
It's kind of like having a longer duration cam on a piston engine
as far as I understand.
But then you can do bridge porting, which is where you take that even further.
And these are just more extreme options.
The air is coming in through this intermediate plates
instead of directly into the rotor housing.
That's how it enters the rotor housing.
It's entering from the side of the rotor.
And so the thing about the side port is you have higher intake velocity
because you have more ports, because you have more plates than you do.
Just the dynamics of it makes the intake velocity faster.
And so the engine is easier to drive around.
And you also generally don't have as much overlap unless it's a really extreme bridge,
meaning that your intake and your exhaust are not open at the same time as much.
And so that's much easier for an engine that is turbocharged.
Because when you have a turbocharger, you have to be careful with the overlap
because you can end up with a situation where that vacuum,
the reason you hear them brrap, and they go brrap, brrap, brrap, brrap, brrap.
The same thing as a big cam on an NA motor,
the intake and the exhaust are open so long that you're pulling the vacuum
and the intake manifold is sucking exhaust back through the intake port.
And so when you're under boost and you end up with back pressure in the turbine housing,
you can actually push exhaust back through the inlet.
So there's just like a...
Basically, peripheral porting is the most extreme form.
But when you peripheral port a motor, you're putting the air directly into the rotor housing.
Instead of having those sideports, you're actually blocking the sideports off.
And a lot of people use epoxy to do that, like a liquid metal type deal.
But I think it gives you a throatier deeper sound
and it can give you more power in the upper power band,
but it increases your volumetric efficiency just like a cam.
But you have to be really careful if you have a turbocharger
that you don't actually end up with a net loss from that
because of your back pressures refeeding exhaust back through the intake.
So that's one thing.
And then also your low-end drivability,
it can cause the car to want to buck and kick on and off throttle
because of the fact that the intake velocity is slower since you have bigger runners.
So there's a balancing act here.
And I chose the peripheral port just because it's cleaner
and it's actually simpler to do on a four-rotor engine or a five-rotor engine
because of the fact that you can get away with four runners on a four-rotor
or five-rotors on a five-rotor rather than ten.
Yeah, it definitely reduces the complexity of fabricating an intake manifold for sure.
In terms of what you've just talked about,
really the comparison to a piston engine with a very large cam
with a lot of overlapping duration, it does really hold true
because we do see you start getting into cam duration for a full-on race engine
and they're not going to idle at 600 RPM anymore
and they're not going to drive really nicely until you're up higher in the rev range.
So kind of the same thing.
Is the ways of combating this poor drivability with these,
let's say bridge port and peripheral port engines with modern ECUs,
the amount of control we've got now,
or is it just impossible to get perfect drivability with that kind of porting option?
Well, I think you can get close.
I don't think you're ever going to get it to drive like a side port or a mild cam engine.
You're always going to have, I guess people will call it like camlash if it was a V8,
but you can get close.
Now, it's exacerbated by having a dog ring gearbox that backlash really brings it out,
especially on this transaxle-based car where you don't have any slack in the drivetrain
from a Guibo or a driveshaft, you really feel it.
But you can really get around it by transient throttle enrichment settings,
which I've found to be just wild, the stuff that I'm using.
Now, I think a lot of that has to do with the placement of the injector,
because it's not easy to place the injector close to the motor directly into the port
on a peripheral engine if you want it to be clean and fabrication-wise.
And so now that your injector is further away,
there's more delay at trying to get that fuel into the motor
and you're dealing with the fact that you have low intake velocity.
So you end up with this like transient period of time when you stab the accelerator,
that the fuel is going from a suspended state under vacuum,
almost like a gaseous state is how I would imagine it.
And then you stab the throttle, it falls out of the suspension,
and now you've got to cram that air into the engine really quickly before the boost hits.
And so you'll get like these lean hiccups and the car will be stuck in this like bucking process.
And people probably seen it in my video when I'm tuning the five-rotor car,
you can see that happening.
And so what I find is that they want a just a ridiculous amount of transient enrichment fuel,
like way more than you would ever realize so high that you think something's wrong
and you end up putting so much damn transient enrichment in.
But you have to do it for a very short duration.
So incredibly quick duration, but a really big punch.
And that gets them running really crisp.
And so I was able to get, you know, this five-rotor car is fairly responsive.
It does have a little bucking because of the super lightweight flywheel.
And again, because it's transaxled, it's sequential or dog rings, the banging around.
But, you know, if you get after it, I mean, it's really clean and crisp
once you do the work on that transient enrichment.
So that's what it all comes down to with the ECU.
And the other thing, which not to give away too much information,
but this would be helpful to people that are trying to do these kind of setups,
is I find that you actually have to scale the enrichment per load.
So not just the same transient enrichment settings for, you know,
fourth gear just applies to the whole car.
Generally, you can get away with that on like a side port.
You use the same transient.
If you can get it, you know, stabbing at 4,000 RPMs in fourth, it's probably good in fifth.
But I find that I've tuned a few peripheral turbo cars now and semi-peripheral
that maybe you don't notice it, but you can see it on the semis or the bridges.
But you definitely notice it and feel it on the peripherals.
If you use the same amount of transient throttle at fourth gear that you do in sixth gear,
sixth gear will be a lot more lean and you'll have a big pop when you nail the throttle.
So you actually have to do, you know, all the way from neutral for a second,
third, fourth, fifth and sixth has to have its own transient throttle enrichment table.
And then you scale for each gear position.
And then I also have the clutch setup to where when I do a blip,
if I'm going to do a clutched downshift, I don't like to do a clutchless downshift.
I think it's just unnecessary where unless you're really racing.
But when you do that blip, you have to account for that too.
So now you need to have a neutral override to make it free rev really nice.
So the enrichment settings for free rev as opposed to one, two, three, four, five, six,
all different.
And that's what takes the majority of the time to get the peripheral right.
The other thing is that you get, I feel like kind of a lying air fuel ratio.
I don't believe that the air fuel ratio is always exactly what you think it is.
And I think that that's because you're getting this pulsing coming in and out of the motor
that it's diluting some of that the combustion mixture with inert gas
because of the inevitable amount of reversion that's occurring.
So you really have to...
What I do is I try to tune them as rich as they'll possibly run until they misfire.
And then when they misfire, I know that that must be rich, right?
And then I back off until it no longer misfires.
And that's about where I keep my air fuel ratio.
It doesn't really matter what the absolute value is.
That's a good point.
I think it's very easy to get sort of tied up on what the wideband is telling you.
But you're absolutely right.
I mean it's no different to tuning a really big cam piston engine with a lot of overlap
and particularly an idle with all of the overlap that's going on.
You're getting basically absolute garbage out of your lambda sensor.
So I've always thought it's a case of understanding what's going on
and then basically giving the engine what it needs in order to give you the right results
as opposed to I need to tune for X air fuel ratio and be damned how the engine's actually responding.
I think that's that closed down attitude that a lot of tuners will have when they first get started.
And as you start building up some experience and you sort of understand more of what's going on
you realise that that's not going to get your results in every situation.
Hey maybe you're tuning a stock engine with small cam or side ports in the case of a rotary engine.
And yeah that'll get you by.
It's just a case of giving the engine what it wants.
To add to that I don't have a lot of experience with this because for me this is a hobby.
So I'm kind of in my own world with this but I do talk to a lot of people.
I mean everything to me is as much information as I get my hands on.
I appreciate it.
So I try to talk to as many tuners as possible.
And my method is always ask a million questions even if you look silly.
People will talk to each other and say did he just call you and ask you the same question.
And then I'll get the consensus from everybody and then I'll make my determination from that.
But in doing that I've learned that a lot of the drag racer guys seem to from my perspective.
So no hate to anybody but from my perspective it seems to be a lot what you're saying.
And I don't blame them for it because if this works then why not repeat it.
But I think a lot of people in the drag racing and respect to them because they're going super fast
running crazy boost on some of these 13 B's like 70 PSI right methanol.
But they kind of have like this strict absolute values that they chase.
And so specifically to that I want to talk about exhaust gas temperature.
And this is something that I was just curious to know your thoughts on you know on or off the podcast.
So there's been this like kind of a school of thought and I don't think everybody subscribes to this.
But you know for example one of the apex seal manufacturers told me do not run this apex seal over the EGT of 1650 Fahrenheit.
Now I can't remember what that converts to in Celsius was that like 800 degrees Celsius or something.
I'm just going to figure out exactly that because I cannot convert from Fahrenheit to Celsius in my head.
Yeah what do we have 900 C. So there we go.
Yeah that's a number I can get my head around.
Yeah so they'll say there's this absolute limit 9 RC OK.
And then like some of the ones guys told me the same thing on any cars tune it to 900 C OK.
So I think that there's like this.
There's this thought that there's if you go hotter than that you're going to melt the apex seal OK.
But the thing is like the exhaust gas temperature to me and I could be wrong.
I don't think it necessarily represents the actual temperature of the apex seal.
It depends on the situation.
So it depends on whether or not the other conditions right.
So there's two conditions here.
The condition where the engine is running really lean and that's why your EGT is really high.
But there could be another condition where you just have a retarded timing and the engine is really rich and the EGT is really high.
You just absolutely nailed nailed exactly what's going on there.
That is why EGT can't be considered in isolation in my opinion.
People try and link EGT to combustion temperature because obviously the apex seal as far as that's concerned
it's the combustion temperature that matters.
We can't measure the combustion temperature.
So we're using EGT as a proxy for what's going on inside the combustion chamber.
Fine that's all we've got access to but we need to understand that just as you said
not only is the EGT going to be affected by boost and air fuel ratio
but it's also going to be affected by your ignition timing.
So if you're running super conservative timing which a lot of rotary tuners will do for obvious reasons
your EGT is going to be up for the same air fuel ratio.
Now that doesn't necessarily mean that your combustion temperature is up
but you're reading that higher EGT.
The other aspect of this which is so easy to overlook is the importance of where your EGT
sensors are in the exhaust manifold.
You're going to get a difference in your EGT reading if it's right by the exhaust port
and it's going to also be much higher if you're in the centre of the runner versus the side of it.
The further away you move from the exhaust port so there's all of these things that are so important
and when people are opening and closed tips so I mean we wouldn't typically run an open tip EGT
sensor in a turbocharged engine, particularly in a rotary engine because they're just not going to last
but they respond quicker in my own experience with my drag car.
You've got a higher EGT reading from an exposed tip sensor compared to an enclosed tip sensor.
It becomes a moot point because they simply don't last.
And then the final part I was going to say about this is a lot of people are using EGT
sensors for individual cylinder or in your case individual rotor fuel trimming.
Most people would expect that every rotor or every cylinder is running the same but that's
simply not the case.
We can get biases in our intake manifolds, there's a range of different aspects there.
But if you're going to use them for that purpose it's critical that every sensor is installed
the same depth and the same distance from the header flange because otherwise it would
kind of all better off.
I actually went a little further than this as well with one of our development cars here
in New Zealand which was since sold.
This was a piston engine but we installed individual cylinder EGT plus individual cylinder
lambda and we found that when you match the EGT within let's say 15 degrees C, the air
fuel ratio actually wasn't the same.
Wow.
The air fuel ratio, when you match the air fuel ratio on the four individual cylinder
lambda sensors, then you actually got a variation in the EGT, I can't remember now.
But it might have been 50 or 60 degrees C.
So there's just not a lot of black and white in this and it's that Dunn and Kruger effect
of you think you know everything and then the further you go into this, the more you find
out, the more you realise there's just so much more to learn.
So true man.
And that's the whole reason to do it is to find out these things.
This is why I love it.
I tell my friends and we joke about it.
I don't really care about it working as much as I do about knowing how and why it works.
So it's just like this is the greatest information.
What you just said because I've never had the experience to be able to do that, to test
the actual air fuel ratio and especially when you have a multiple rotors like when you're
dealing with five right with a single plenum.
It can be really risky to be making these significant adjustments to try to chase uniform
temperature across all the rotors.
And I stumbled across this aviation paper that was talking about back in the old days when
you had to trim your EGTs at altitude as your measurement for your mixture from the density
of the altitude.
And they were saying do not try to equalise all the EGTs.
You'll blow a piston up.
So kind of my thought on this in regards to the drag cars is I've got a buddy that is
in, I'm not going to call him out, but there's a buddy that I know of in one of the northern
states and he's got a beautiful car and he races it and he's frustrated with it because
he's pushing the limits, in my opinion, of E85.
So E85 big difference from pump gas obviously because you have the extra octane and cooling
potential.
However, it still has its limit, right?
So if you're going to push E85 to 60 psi, I believe that he's around 55-65 psi.
They had time for me to know.
Yeah, you're starting to flirt with the edge, right?
And so just running the engine really rich, so what they're doing, what they've told
me they do is they'll run it to the point at which it misfires and then they pull back
and they'll say that actually a lot of the drag guys will get it to gargle on the dyno,
the sound of like a little gargling in and out, kind of like a ghosty misfire.
And then they say, okay, then that's going to make it be able to handle the track conditions
because on the track it might heat up and use more fuel.
Okay.
So they put it right on the edge, right?
And then they give it enough timing to keep the EGT under 900.
And so I'm saying, okay, don't give it enough timing to pull the EGT.
Don't use the EGT as absolute value.
And I'm like, well, how much timing?
They're like 15, 16 degrees.
Okay, so that doesn't sound like a lot of timing, but when you consider that you're running
65 pounds of boost, you have to look at your intake air temperature, right?
Well, your intake air temperature is going to be a delay.
You're not going to see the actual intake air temperature, the immediate that it hits
with all that CFM.
You're kind of seeing it on the backside after you left the throttle.
So even though it goes to 160 Fahrenheit or 200 Fahrenheit, it might actually be hotter than that
because you're just not capturing that information unless you have a K-type thermal couple on your intake, right?
So if you're pushing that degree of timing and they're saying, oh, the apex seals are warping,
they're not seeing knock, they're not seeing detonation to the extent of rotors like denting and stuff,
but they're seeing apex seals warp and they're like, ah, they warped and we have to put them back together.
So what I'm saying is pull that sucker back to 10 degrees or 8 degrees or 6 degrees of timing.
Make sure you got a big ignition system on there like a CDI.
Run it as rich as you can and maybe even consider adding water injection, not water methanol, water injection.
Get the combustion chamber temperatures down.
You're trading one side of the engine to the other.
The higher the EGTs go by retarding timing means that in my opinion it's actually getting cooler on the combustion side
and that's the consequence of the inefficiency on one side becomes hotter on the other.
And then you're only worried about melting the turbo, not warping your apex seals.
That's another good point that I was going to raise there.
We do need to still be mindful of EGT in the fact of the matter.
Our turbine wheel material is going to only withstand so much temperature for an extended period of time.
I think sort of the current crop of turbos, maybe sort of 1000-1050C is about the limit there.
So yeah, I would have also said that 15 to 16 degrees timing with 60 pound of boost even on E85 fuel is crazy.
Very optimistic, I don't think I would quite be there.
Interesting though, so when we talk about air fuel ratio targets for rotary engines,
and I'll use AFR instead of lambda which I typically tune in.
For a typical piston engine running pump gas, turbocharged piston engine running pump gas
and let's say it's 20 psi of boost, we might be running somewhere in the region of maybe 11.5 to 12.0 to 1.
You could go a little bit leaner than that.
Once you sort of take on target air fuel, I just already talked about the fact that you're not taking this
necessarily as gospel, but what sort of target air fuel ratio would you be looking at for a comparable
stock 13V running the same sort of boost pressure?
Yeah, if we were talking about an engine that didn't have a lot of overlap where we could really trust the sensor data,
my targets would be without a doubt 11.0, maybe richer, it depends on the boost.
But if you're going to run up to 1 bar and probably needs to be around 11.0, maybe at 11.2, I wouldn't go any leaner than that.
I find that the gains are just going to come in more boost.
So add boost and keep it rich.
If your ignition system can handle more fuel, then you can take it down to mid-tense.
What you'll find is you can run retarded timing and I think the timing is really what's going to dictate the longevity of the engine.
Push the timing as low as you can to where you're happy with the temperatures not so high you're going to melt the turbine off.
So really the timing is like you got to find that happy medium where you're not going to melt the turbine off,
but you want to air on the side of caution, leave it pulled back.
So if we're going to run like 1 bar, say pump gas, to me that's going to be the limit.
I'm not going to go much over 1 bar, maybe 16 psi.
Then I'm going to have the timing somewhere between maybe like 12 degrees, 13 degrees,
and people might think that's really conservative, but I think I'm at the knock limit of the fuel.
I'm starting to flirt with that.
I'm going to run a 10-5 if the ignition system will take it and whatever the power makes is the power that it makes.
I'm not going to sacrifice reliability for an extra 20-30 horsepower that you could get by leaning it out
and you'll find that my engines have always lasted.
Now again, I'm not competing and I'm not running multiple laps and stuff,
but for cars that I drive on the street and have had them last for years, that's always been the recipe
as much fuel as they'll take before they start really falling off and misfiring.
OK, so I think this is where the difference in your philosophy comes in compared to a piston engine tuner.
So piston engines, we will typically run, as I mentioned, a linear air-fuel ratio,
maybe 11.5 to 12.0 or something like that, and you'll find that with those piston engines,
you go much richer than 11.5, you're going to start to see the power drop away,
and once you go probably richer than maybe 11.0, 10.8, the power is going to fall off a cliff,
and unless you've got a hell of an ignition system, you're probably going to find that 10.5 is probably about the rich limit.
So you'll see it fall off on power despite it not even misfiring?
Like if you went from a 10.8 to a 10.0, you'll just see a big hit in power?
Correct.
Yeah, we don't notice that.
Absolutely.
Yeah, I don't notice that on the rotary.
OK, interesting.
So my experience has actually been the polar opposite, like our FDRX7.
If I run that at 1 bar of boost and 11.5 will make, I don't know, let's call it 400 horsepower,
just for round numbers, I don't know what it actually would be, and I go 11.0,
I probably lose, as you were talking about before, 15, 20 horsepower, 10.5,
that's probably about the point where the ignition system's had enough as well,
it might lose another 20 horsepower.
So I think a piston engine tuner's mentality will be like, well, we lost horsepower,
so let's lean it back out.
And they're also applying that same approach to the ignition timing.
So the way you tune a piston engine, you'll start with the conservative, retarded timing,
add a couple of degrees, see what it does to your power and torque, yep, everything's OK.
We're listening for knock, we'll add a couple of degrees, so we're creeping up on MBT timing
until we either reach MBT or alternatively we start to hear the onset of detonation,
obviously then we stop, we pull it back, add a safety buffer.
Now I think when you start applying that approach to rotary engines,
it becomes incredibly dangerous because now you've got a lean air-fuel ratio
and now you're adding timing, the rotary engine's going to be more prone to detonation
because of the higher combustion temperature of the lean air-fuel ratio.
And you'll start to see those gains in power and torque but you're flirting with disaster.
One other aspect, if you look, it's hard to do this without some visuals but if you looked
at the relationship between torque on a dyno and a fixed steady state RPM and load on a piston engine
and you did a spark, a sweep between let's say 0° and 50°, you're going to see initially
from 0° which is obviously very retarded, you're going to see a very sharp increase in torque
with every degree you add in.
And then you'll find that once you get to maybe 20°, it'll start to plateau or flatten off
a little bit more and then maybe 25°, that's where at plateaus you find MBT
and then as you advance the timing beyond the MBT, you'll start to see the torque fall away again.
Now if you do that on a rotary and I highly recommend no one does,
but you will see the same trend or a similar trend but the relationship,
the magnitude of gains you get per degree of timing are nowhere near as significant
as the piston engine, that whole curve is much flatter.
So long winded way of saying it's not worth chasing in my opinion, torque and power
on a rotary engine with timing because the gains per degree of timing aren't massive
and the repercussions of running even into light detonation are just so drastic.
So I tend to add a little bit of timing from a very conservative point
and once I first start to see that my torque increase per degree of timing
is just starting to drop away, I'll leave it there or even pull a bit of timing out.
100%, I'm on the exact same page as you.
In fact on my engine, it's been a while, I haven't had EGTs on a sideport
but on the peripheral port, I don't really care so much about the torque curve
like what you're saying, the point of diminishing returns.
So I'll do exactly what you said, I'll add maybe a degree or two
or I'll subtract a degree or two just to kind of see where we're at
like what the percentage change difference is on the torque of the dyno
and then I'm also looking at the best EGT, like what's the result in EGT
because I'm going to lean towards the most conservative timing.
So I'm always going to be much further back than what you would expect.
And then the only reason I'm going to add a little bit back in is not for power
it's going to be to keep the exhaust from getting too hot.
So like this five-rotor engine for example, the cool thing about it is
that it's got so much displacement you don't need to ask a lot.
So I keep the timing way back and also keep the split really wide
and then just make the power with the displacement
even if it's not very efficient because it's going to last
and I think that's the name of the game
and just enough timing to where it's not so hot that you're melting the exhaust off the car.
The thing that I'm really focused on on this car is the EGT variants.
I see some weird characteristics like rotor five at idle is much cooler than one, two, three, four
and then when you start getting into boost all of them are coming up
but then as you get to the top of the power band one and five creep away from two, three and four
which is not the same characteristics as the four-rotor
which have identical intake manifold characteristics and designs and lengths.
So it's really strange that there's these variations
and I'm really glad that you hit on the fact that you put individual lambda sensors
and did not see a one-to-one correlation with the exhaust temperature
so I'm kind of trying to think how to investigate this out.
My biggest fear is always when you're looking at your comprised air-fuel ratio
that it's not speaking for the leanest rotor or whatnot.
Well no, I mean you're only seeing that the lambda sensor post turbocharger
is measuring the average of all of your rotors or cylinders
so I think that's another aspect that's very easy to overlook.
You trust that implicitly but all it takes is to have one or two rotors that are quite lean.
Maybe one rotor that's way too rich and your wideband is going to give you
what you think you should be chasing but obviously you've got one or two rotors
that could be right on the brink of destruction.
Yeah certainly, I mean one way I've been able to prove it
what I'm still trying to work this out is I'll add a bunch of fuel to one of the rotors
until like okay let's say that one of the rotors is hot.
It's reading hotter than the other four.
Okay like rotor one it seems like the outlier that doesn't make sense right
because we've moved the injector around, we've moved the ignition around,
we've double-checked the compression blah blah blah.
Checked all the things right but number one still getting hot under boost okay
so then let's throw a lot of fuel at number one to the point at which we start hearing a misfire.
Okay but we haven't touched the comprised air fuel ratio the target is still the same
so we're just isolating number one because he's running the hottest
and we're going to throw a shit ton of fuel at him.
Now if we start hearing an audible misfire obviously it has to be misfiring on number one
and then the peculiar thing is that the EGT isn't dropping in line with the other four
so that tells me that the EGT is not representing the actual air fuel ratio
in combustion chamber one despite the fact that the probes are in the same spot the lengths
the runners and all the stuff is jiving.
So the other thing to consider not to get too sidetracked here
the eccentric shaft design okay we assume that the low-bangle offsets are always exactly accurate
and I had a four rotor engine that was initially built by somebody else
and then we rebuilt it in the United States when we had issues
and when we actually blueprinted the crankshaft and had a look at it
the low-bangle offsets were not always 90 degrees like rotor one to two was more like 88 degrees
and another one's like you know 92 degrees and I'm not really sure how much that would play into this
but obviously if every rotor is not hitting at its respective top dead center 90 degrees from the other
on an engine that's even firing 90 degrees well that's going to affect your EGT
and your combustion chamber efficiency rotor to rotor.
Yeah 100% I mean I think that's sort of things that we like to expect that we can take for granted
but clearly we can't so that'd be no different than having the crank throws out on a piston engine
I mean at that point yeah all bets are off.
Now something you just mentioned and again rotary specific here
just before you mentioned the trailing split or rotary split
rotary engines have a leading and a trailing spark plug and they fire at slightly different times
can you give us a bit of an understanding of the importance of rotary split
and maybe why we shouldn't be using rotary split to try and chase more power and torque?
Yeah certainly so the split timing dictates when the trailing spark fires after the leading plug
unless you want to actually fire it before the leading plug
so you know again all the things that we've been talking about is about relation to power
so these things are not necessarily the same fundamentals for drivability
but like when you're in power the trailing plug is exposed to the combustion stroke
like a lot earlier than the leading plug and so if you were to fire them off at the same time
as the rotor is coming around as far as I understand like you can cause detonation
or knock because it's just not in the same place on the rotor housing
and they're kind of like opposing each other
so you want to fire that trailing spark behind the leading spark
like by a certain amount of degrees and like the factory traditionally does it like maybe 15 degrees behind the leading
so like if you're leading ignition timing which is when we're talking standard timing
and this is for the audience right 15 degrees okay well then if you had a 15 degree split
then your as far as I understand your trailing would be firing it like at zero
cause it's 15 degrees behind the leading right
okay so now I haven't tried this because I'm not going to flirt with you know the edge of pain
but maybe you've tried it on the dyno
however I have found that pulling that split timing back to maybe 12 degrees or 10 degrees
might give me a little bit more power
but not a significant amount of torque increase or EGT drop
so just leaving it at 12 to 15 doesn't seem to be a big of a difference from you know running it at you know 10 degrees
I haven't really gone any lower than that I've experimented with ethanol
so I just don't ever really want to want to run the risk of that potential knock occurring by running them too tight
and so what the theory is basically like you could run a tighter split with less leading ignition
or you could run a wider split with more leading ignition
I would rather just run them both conservative because you know let's just make the engine run forever
and let's trade that 30 40 horsepower for another 30 40,000 miles
so I think I'm getting a sense from your philosophy as we get deeper into this of why your engines are lasting
I think interestingly back when I was very early in my tuning career
the sort of the ability for a lot of aftermarket ECUs to run the rotary engine properly was much more limited than it is now
and it wasn't uncommon for ECUs to not provide a trailing split map
and you're essentially enforced to run both the leading and trailing plugs with the same timing
and yeah as it's been explained to me it's essentially no different than advancing the timing overall
and therefore you start running the risk of knock particularly if you are running leading and trailing plugs at the same time
and you're also using aggressive spark advance, it's just not a good combination
so yeah 15 degrees generally is about what I'd run as well
as you say you can see a small gain in power and torque but just like you I think the gains really aren't worth pushing
the boundaries there
that would be way past threshold right according to you know the absolute value that would have warped the apex seal
and it was running completely fine we didn't even notice it until we looked in the logs
we thought it was just anomaly with the sensor until I realized that the wire the leading plug wire was you know it was arcing out of the wire
and it burned out the ignition pack and so basically the reason why it was running so hot was because that rotor was only firing on the trailing
and the trailing was a 15 degree split so if I had you know 12 degrees of ignition timing
then it was literally at negative five or you know five after top dead center or something like that so that's why it was so hot
and then that proves to me at least that high EGT is not the death of your apex seal
actually if you are rich and you have high EGT then it actually proves that your combustion chamber is probably happy
the other thing that we could bring into this is water injection that's something I've always used on my engines
now I've always had to be pretty liberal with my water injection usage because I never wanted to rely on it too much for the cooling potential
although from the way it's been explained to me is that it cools the engine better than additional fuel
so like if you're going to run you know 10% richer than stoic or whatever and you were going to do that with water
instead of you know fuel it's actually more effective because of its heat evaporation properties
however because you can't account for perfect distribution and it's not an actual injector
you don't want to lean on it but what I'll do is I'll tune the cars until they're running crisp and reliable
and then I'll just sprinkle enough water injection in there to where I feel a little bit of misfire and power loss
and I'll pull it back just a little bit and whatever that is is what we leave it at
it just makes me feel good to know there's extra water going into the engine to help display some of the heat
that may be occurring from you know higher loads and higher intake temp
just while you're talking there I just wanted to get some numbers so the latent heat evaporation of water
is maybe two and a half times greater than ethanol I just looked at ethanol
so yeah you're on point there
I think that just also really highlights with your leading plug being out
it just really highlights that that link between EGT and combustion temperature is not as set in stone
and well correlated as most people would think
but I think maybe around an hour and now it's probably time to jump into the five rotor
so I guess let's start at the start, you had the four rotor at this time
what was the impetus behind the five rotor project and how did it kind of develop?
so my favorite thing about the four rotor engine was the you know my inspiration was the 7A7B
the Mazda 24 hour car and it sounds like a formula one V8
those are the only V8s I've ever had a chance to hear that was like the last era before they went to the V6
and it's that scream and high pitch just lovely sound and I noticed that the four rotor really sounded like that
of course I love the three rotor too and I love the sound of the six rotor
and so when I had the four rotor car when we initially you know did the project
I had this whole package that came from a company that you know I thought it was going to be everything that I wanted
and when I put it in it was a turbo engine it just didn't sound right it sounded like a 13B
and I noticed there's a lot of turbo or NA four rotors that just don't have quite the sound characteristics of the 7A7B sound
to me that was the whole purpose was the sound I think there's like a visceral human experience behind having that sound
when you're driving a car and I can't even describe it's like you can just be driving up a hill at 10% throttle on you know the four rotor
and it's just it's like ecstasy just here in the sound I mean it's actually more fun to drive slow and wind the gears out
and here it echo off the mountains and it is to drive fast and it's over before you started
so that was the whole you know goal and you spend you know tens of thousands of dollars and thousands of hours
and you don't get the sound you're like oh shit what was the point of all this
so I really wanted to understand that it was frustrating because there's a bunch of hero cars to me that sounded amazing
like Brent Coran in New Zealand his car he had a drag car RX2 that just sounded beautiful
and so there's only like a few turbo cars that came close to that sound
and so you know we ended up having to rebuild the motor and I teamed up with these really cool guys that are in Indiana
that Richard send twins and so that's when I really started learning we blew her in the crank rebuilt the engine
took a look at you know the turbocharger sizing and you know God and all the nitty-gritty details
and while I'm looking at this I'm going I wonder why this thing didn't sound right
so I start talking to this wonderful fabricator from Birmingham his name is Walker Morgan Biga
hero of mine too he's older than me and always looked up to him growing up he was way into EVOs
and badass EVO fabricator and so he's like the top guy around here phenomenal welder
and so I'm like dude do you think that it could be because the manifold's not equal length
and he's like I don't know I don't think that that's it I think it's because it's a turbo it just ruins the sound
which is kind of like debating on this and there wasn't a lot of information so I get in contact with this gentleman
Carlos Lopez from CLR Racing and he's you know old school guru who's been around a long time
and he helped rebuild some of the motors on the Mazda Le Mans program like he's worked on some of those like 787 style
prototype cars and so he tells you like David he's like it's all to do with exhaust design
and your intake design and he points me in the direction of these Mazda SAE papers
so I start reading these papers and start learning about the collection and the merge order and all this stuff
and I'm like holy crap like there's a whole thing to this so we develop what we design out this manifold
and it's really tricky because now we have to work with the same space constraints because the intake
and the location of the engine we don't want to have to redo all that so I go to Walker I'm like dude
we need this length runner this merge order into the collector this merge angle into the collector
like this diameter to me I need to do all this and fit it all in here equal length and it's got to be within like
0.1 inch and he's like are you kidding me so he's like alright I don't know if this is going to work
but we'll do it but you're going to pay for it and I'm like yeah I'm going to pay for it let's just do it
go all in let's just do it and so he builds a PVC collector to make sure he can make it fit and then he makes it all
and I can't remember what the materials were I think we used piping instead of tubing like schedule
schedule 10 yeah I think it was schedule 10 yeah so we get this thing together
fired up dude with the manifold with the turbo off right just to see what it was going to sound like
and I swear to God it sounded exactly like the 787B and it was just ripping screaming sounded amazing
I'm like okay this is it this is the key it's all in this exhaust design and that car just it just ripped
from that point on and so then I really started diving into it and analyzing you know trying to figure out
how does this sound work like why does it make a difference how like what's the music theory behind it
and I was able to unpack that basically there's a harmonic relationship that your ear can proceed
between the sound of the crank shaft on a piston engine or the eccentric shaft in relation to the combustion
firing events of either the pistons or the rotors and that creates different harmonic relationships so on
a four cylinder or an eight cylinder it would be an oct an octave relationship between the not
necessarily like a one to one it could be like two octaves or whatever but it's an octave jump and so
basically because a rotary fires twice as many times as a piston engine per revolution it creates
twice as many pulses at the same rpm so it's kind of synonymous to say that like a four rotor would be like a s2000
engine at double the rpms okay and then that's similar to what a v8f1 engine sounds like because on
an engine like that with a flat plane style crankshaft where the pulses are divided into two collectors
your ear is only hearing the half the frequency because you're hearing one collector of the motor so it's
basically like yes it's a v8 and it's kind of like double the frequency but you're really it's
if you were to take an s and i i did this like i took four cylinder sound clips and i would like
double them though in the wave file the frequency and it sounds just like a four rotor and then you
could take a flat plane crank v8 that's at a lower rpm double it sounds like an f1 right so i'm like
man maybe that's what's going on i start looking at the sound and i'm like okay let me take a pitch
finder and let's play with a pitch finder so you could take a pitch finder like for a musical
instrument that tells you you know play a on the guitar it's like 400 whatever hertz 440 you take
that pitch finder and you listen to the four rotor i'd rev my engine up 9 000 rpms it's exactly like
600 hertz and then you can backwards calculate out the math and you can figure out the relationship
between the crank and the rotors okay so and that's an octave relationship you've really gone deep
down this rabbit hole yeah so so then we look at the five rotor that doesn't exist at the time
we're like okay we got a four rotor we got a sixer so what does this mean okay so the six rotor
or a three cylinder or a six cylinder or a 12 cylinder all of these have like the same octave
relationships it's just a matter of like how high that frequency is above you know how far the octave
is at multiple octaves okay so like a six cylinder engine it's not an octave now it's an octave plus
a fifth so a six cylinder like a 2jz or an rb if you collect it equal length and you follow all the
rules to extract the perfect you know the pulses sequentially and they're not stacking up in the
collector you're going to get a perfect fifth musical relationship and that's what your ear
really loves and that's why some of these inline six cylinders sounds super high pitched right
you know v6 or v8 the sounds can change a lot because you're not necessarily like a flat plane
style crank and the firings are not you know equivalent like that but in theory if they were
even firing engines and you were to collect them like six into one it would be really similar
frequency to an inline six okay so not to get off you know too far off point here but basically the
math is saying that a five rotor would sound like a five cylinder at double the rpm and so the five
cylinder is really similar to the v10 engines that are even firing v10s now there's a lot of confusion
because there's a lot of v10 engines out there that are not even firing v10s and that's because
they're really difficult to balance so they have an odd firing geometry they don't with meaning that
in a 300 or 720 degree revolution of the crank the pistons don't fire every 72 degrees they
like overlap one another so like a dodge viper for example that's why it doesn't sound like a
really messes with the sound yeah right yeah so but there's a few key cars that do have that
sound like the lexus lfa that you know is remarkable sound quality and so a lot of times people think
well it's because the yamaha exhaust and these kind of things well those those are the secondary
characteristics like tamber and bass and like that kind of stuff but the true frequency and the
sound in the harmonic relationship falls to that even firing geometry of the 72 degree crank angle
offsets of those motors and then having a properly collected exhaust system and the fact that you
know the f1 revs to like 18 000 rpms so in theory a five rotor at 9 000 rpms would fire so many times
per revolution and it would create 750 hertz and if you took a pitch finder and listened to an f1
v10 on youtube right now and you found one that was at 18 000 rpms it would actually be 750 hertz is
what you would hear although the engine's actual firing frequency would be 1500 you're only hearing
750 because of the v so i'm like okay we got to do a five rotor it's going to sound like a v10 f1
and it's going to create the relationship which would be the major third harmony and the thing
about the major third harmony is in music that's the interval that we use for joy so like if we're
composing a piece and we want to make you feel sad we use the minor third harmony or we use the
diminished fifth and for suspense and chaos and stuff like when like a Darth Vader's coming that
that's the diminished fifth when the saints go marching in is a major third so it's this interval
of joy whether or not we realize it that we use it and all these music uses that interval for joy
and so why are we so attracted to the v10 f1 sound in the heyday as opposed to the v8 and the v12
which both sound amazing don't get me wrong but that v10 has something special and it's because
of that feeling of joy that you get from it so i'm like okay if we do a five rotor maybe we can
recreate the sound of course we have this uncertainty because it hasn't been done yet but that was the
whole reason to do it i'm like i was willing to sell my car and put it all on the line and just
put the next four years of uncertainty into just to see if it would sound like it does because
that's that's my whole jam man is just do it just for you know for the help of it right i'll stop you
there david and there's a bunch of stuff obviously again to unpack i can absolutely get everything
that you've been saying about the equal length runner the order of the collector et cetera
on a naturally aspirated engine i clearly you've proven my theory wrong but i would have thought
as soon as you introduce a turbocharger into the system kind of all bets are off so is the turbo
charger kind of irrelevant to the sound the engine makes it's 100% irrelevant to the frequency
and the harmonic it only affects the secondary characteristics so when you're talking about
like a trumpet versus a french horn versus a trombone they could all play the same noise the same
frequency the same you know high pitch you know 200 300 hertz whatever but the french horn is going
to have a darker sound and the trumpets can have a brighter sound the cornet's going to have a warmer
sound the trombone so to speak so the same thing with the turbo is the larger the turbo the more
the less muffling is going to occur the turbo just seems to create a more rounded sound like it's
not so edgy and raspy but that's about it and that the key is that you have to do your collection
before the turbo and if you're going to use the turbo as the collector like if everything's going
to merge into that t6 flange well then you better be damn sure that everything is coming in perfectly
and that you're collecting in the firing order of the engine that's also key well let's actually
talk a little bit about that collecting in the firing order
maybe start for those who are maybe picking up the pieces what that even means and then
how that will affect the sound yeah certainly so i'm not really sure if it really would affect
the sound because i haven't tried it otherwise but i do know that that's the most ideal way to do it
for scavenging and efficiency and so basically if your engine like the four rotor fires one three
two four meaning that rotor one fires first then rotor three rotor two rotor four and another
misconception is that you know when a four rotor fires all the rotors every one fires three times
no it only fires one rotor at a time it takes three revolutions for every rotor to have fired
all three faces and so it's one pulse per rotor per revolution whereas a piston engine is every
other revolution i think the part that people miss with that is they see the rotor and it has
three combustion chambers essentially so so obviously three per revolution the disconnect
there is of course that they're actually geared to the eccentric shaft and rotated a third of
eccentric shaft speed right absolutely 100 yeah and that i see that misconception a lot people
like oh it's a five rotor it must it's 15 000 you know revolutions no it's it's literally firing
like a two stroke it's not a two stroke but it fires as many times as a two stroke because
you're getting one pulse per rotor per revolution if i rotate my crankshaft it'll go pop pop pop
pop one two three four five and then it resets okay so in terms of the collection if you had a four
a four rotor it fires one three two four so going into your collector you want to go in a rotational
pattern so you want to go one three two four into the collector and what that's going to ensure is
that the pulses are naturally wanting to arrive one after another and they're not going to clash
into each other it's kind of like a spiral effect going into the collector as far as what
i understand and then there's a ideal angle that you want to you want to use kind of like the
shallowest angle you can get away with for your space constraints because that's going to help
again with getting each pulse to come one after another smoothly and then there's an ideal length
for the exhaust runner itself now this is not necessarily so important for sound unless you
go way too long so like there's an experiment that i also see i think is a misconception where
people are talking about some guy using stepped headers to make the exhaust higher pitch cool
youtube video really great content but i don't think that that affects the sound either i can't
see how a stepped header would raise the frequency of the sound there's no way to raise the frequency
like when you play a trumpet the pitch is coming from the frequencies of your lips vibrating and
so in a sense is like that's the same thing as the rotors firing or the piston you can't create
more firings than actually exists right so your fundamental frequency characteristic of the engine
is coming from the firing events themselves and you can't exceed that no matter what you try to do
so the idea here is to extract that maximum frequency and anytime that those frequency that
those pulses are clashing with one another then you run the risk of losing the highest potential
frequency that the engines truly generate so you're you're just trying to allow the engine to speak
its full you know voice and so you want to go in a rotational pattern and then you don't want the
runners to be way too long so you know there's been guys that try to do like a 12 into 1 on a v12
to double the frequency but the runners i think the problem is because they're like 90 inches long
then they're not leaving the you know the pulses aren't making it all the way through before the
next one comes to the collector so essentially what you are going from collecting all 12 together
and one you're losing because of the length of the the primaries is too long exactly also it may
just be that when you try to cram all that into one collector they just stack up i'm not really
sure but that would be my thought right okay so then the other aspect here is that there's a
relationship between your intake and your exhaust runner length you have these different orders so
like on a trumpet there's these different orders so like when you're not pushing any of the buttons
you can play like a c a g an e a c like it's like these wavelengths that you know you bounce between
the air like physically is forced to jump through these different wavelengths so it's kind of the
same thing on a motor where you can bring out this harmonic resonance based upon the length of the
exhaust manifold and the length of the runners on the intake manifold and that's the intake manifold
length based from the actual combustion chamber face of the rotor all the way to the tip of the
trumpet so the longer you make the trumpet the longer that intake length is you know considered
because that that metal is actually resonating and it has to do with the speed of sound which is
also influenced by heat and a whole sort of other things but essentially there's this harmonic or
this resonance that's happening between the intake and the exhaust i believe it's called helmholz
resonance and you can target specific lengths that are within these you know defined harmonic
like boundaries or orders so like for a rotary engine maybe the exhaust you could run i've seen
people do like 44 inch runners for the exhaust system but you could also be somewhere in the range of
maybe like 12 to 24 inches but then see if you had an exhaust that's between 12 and 24 inches then
there's a corresponding intake runner length that needs to match with that for the power band that
you're looking for now this isn't going to affect the audible sound so much but it's going to affect
the performance of the engine and the power curve and so you want to make sure that you get that right
and that's sometimes that's a real struggle because you have to be able to package all of that stuff
yeah as soon as you have to start putting in a car it does raise another layer of complexity
I think the other thing when you're talking about the runner length and we see this with the
787B that intake runner length to target that resonance and improve the engine's volumetric
efficiency it's totally dependent on what the current RPM is which is why you see the variable
length intake runners to kind of optimize the volumetric efficiency throughout the rev range
that's actually being used. Let's just park the sound for a moment and come back to building a
five rotor because you can't just go and buy a five rotor from Mazda. Four rotors have been around
for kind of as long as I've been messing with cars but you know what's involved in building a
five rotor, who do you go and see, how does this work? Particularly I mean we know we can stack
the plates and rotor housings together that's not the hard part but the eccentric shaft becomes
problematic. Sure yeah the most important part is that you have to have the eccentric shaft which
is the crankshaft and that's a very complicated difficult piece to machine you have to have
very specific tooling for that and while there might be a lot of companies in the world that have
the capability of doing it to do it small scale just for you they have to shut their whole machine
shop down and retool so it's really hard to find somebody that can make that and there's only a few
companies but one of the companies that has been around for a while is precision engineering in
New Zealand and that's who I used to get the five rotor crankshaft from so I actually started talking
with him about six seven years before I even started up the project it would have been about
2015 when I started learning about the sound stuff and I asked him I was like do you think you can do
a five rotor and he's like yeah you know it might be possible let me know when you're ready to do it
so right before I sold the car when I was ready to make an attempt at contact and I'm like okay
let's do this thing what's it going to take and he said well the major issue would be the balancing
because when you have this odd number of you know five rotors we don't really know what's
going to happen when you look at a piston engine like a v10 it's really difficult because you have
that overlapping power pulse that's uneven 72 degrees like that and so well it's even but
it's kind of uneven it's kind of hard to describe but basically the engine's like trying to
it's called a rocking pair order issue so like if you're looking at a five cylinder
the motor's like trying to bounce itself on the table because there's not a piston coming up
that's counteracting another piston that's coming down directly in does that make sense I don't
really know how to explain it but yeah yeah I mean it's it's another one of those ones that's
difficult to explain without the benefit of some animations or at least a picture so it
doesn't lend itself very well to to a podcast format but yeah I think you've done the best you
can so we get that there's there's potentially an imbalance issue yeah so that was the scary thing
was you know can we do a five rotor because is there going to be a a rocking order or issue
but there's not rocking pairs on a on a rotary engine it's just a magical spinning Doritos
so maybe we don't have a problem here but the issue still would be that we have to balance
this thing and we know that a three rotor has significantly larger counterweights than a four
rotor and a 13b so we can theorize that a five rotor is going to have probably bigger counterweights
than a six rotor or a four rotor and so he's like all right we got to make a dummy shaft and we have
to see if that thing you know so he makes a dummy shaft and use bob weights to spin this thing up
and see you know what would be the ideal firing order and at the same time that he was doing
that experiment there was another guy in Japan that was doing some experiments and so they had
two different firing orders they came up with but essentially the precision firing order
would require significantly more counterweight mass but it still looked like it would be doable
and it would be the easiest way to do it which would be one two three four five and so that was
the crank shaft that we actually ended up having one two three four five and the counterweights are
massive so that's always been the concern however I don't appear to have any harmonic issues or
vibration issues and I'm also using a billet timing support cover it has a ball bearing inside the
front cover just in case because you know you just don't want any of that centrifugal forces or
whatever loading that may occur from that significantly larger counterweight trying to flex that
crankshaft that's the biggest concern with the long engine like this with that much mass rotating
so that'd be your downside as compared to a six rotor or a four rotor would be that
additional mass so that's the most important thing is that crank that's what you start with
so essentially once you have an eccentric shaft is there is there any more complicated to build
a five rotor than a two rotor other than the that your bank account is going to take
yes of course because now you're going to have to get your intermediate plates and your rotor
housings and so with your intermediate plates it's going to be much more challenging to
try to do a side port especially if you're working with plates that are factory plates
and you have to modify these plates with stationary gears that have to be put into the
plates which are basically bearing supports that take the load off the eccentric shaft and you
know help it to perform correctly so you can't just like stick a bunch of factory stuff together
and then you have to make sure that the engine is you know centered up correctly and this is one
of the things that people have a big struggle with because when the longer these engines get
the harder it is to make sure that they're straight because the error over you know over the stack
gets multiplied gets multiplied right so when you're trying to stud an engine you have an engine
that's that long you don't want to just use factory dowels and studs you want to go up to maybe 12.7
millimeter studs and these things have to be really long and go all the way through the block
and you have to have super accuracy so the best way to do this in my opinion was to get a billet
engine made because you can get a lot more of that accuracy with a CNC when it comes to you
know drilling for all of your studding and for the housing and the plates themselves and then you
could have some through studs to help put the motor together from what I've understood is that it's
more difficult to even build the engine because it's so tall so I had a billet rotary store made
really good friends with Steven Cockerel over there he's an awesome guy and he built the engine for
me and we use a billet pro plates and we actually had the plates machine to where they don't even
have the side ports in them so you don't have to worry about the epoxy you know when you're
blocking off the peripheral port and then the same thing with the rotor housings when they
when we had the rotor housings peripheral ported we had some special inserts put in to block off
the water jackets instead of just using your traditional epoxy style stuff that can fail over
time and that also allows us to have a really accurate you know center line of the engine and
be able to dry stack the assembly it's just there's a lot of tolerance concerns that you have to
you have to stick to and then of course like your oiling system and your intake design your
exhaust like all this stuff has to be custom made and so that's you know it's a lot more challenging
than just you know a factory engine it's a big job in terms of the use of the billet parts here
over genuine Mazda is it purely around this tolerant stacking problem as opposed to you
didn't need the billet parts in order to handle the power because I think if I remember rightly what
you're sort of over a thousand horsepower but I mean I guess when you divide that out by five
rotors I mean it's not crazy right no yeah correct I don't think that you run the risk of cracking
plates and you know being at that issue with power when you're only making you know 200 horsepower
300 horsepower per rotor so it's mainly because the quality of the machine work and also the
fact that if you did have a problem with the engine you could replace the inserts that are
inside the billet plate so like if you if you took a factory cast plate and then you had it
specially modified for the stationary gear and then you had a problem with the engine
and you know god forbid you had to resurface the iron well you're going to have all these problems
because now you have to worry about re-nitriding it and all this stuff and that's that stationary
gear modified piece it's not going to be easy to replace so if you had a billet piece you could
just replace the insert which is the wear surface and then you can reuse the part so I think that's
one of the big things now you know there's not a whole lot of cars that are street driving with
billet plates and there's a lot of different brands out there but I find that this billet
pro design seems to be really nice I don't have any smoking or coolant temperature issues or
anything it seems to be really nice so I think it was the way to go. One of the things we here
debated in the piston engine world between billets and and factory cast blocks is the bearing growth
now I'm not a rotary engine builder I've got a a reasonable understanding of what what it looks
like inside a rotary engine and I'm guessing with the way the bearings are installed that
wouldn't be a problem with billet rotary parts am I right or is growth still an issue? I don't
think that it would be an issue when it comes to the actual bearing itself it has been an issue in
other brands where the stationary gear actually tries to come out of the or like it leaks like
the oil around the stationary gear seal or something like leaks because the plate's expanding around
where the gear but like on this specific brand the stationary gears are like their interference
fit where you have to heat the plate up and drop the gear in cold and then that accounts for that
thermal expansion however I do believe that there could be an issue with block growth
for your studs and so I think it's really important that you account for that with like how you seal
up the ends of your studs like the ARP system making sure that your washers and the sealing
mechanism and all that is is perfect because the block is going to expand and contract and I did
have some leaking from that that I had to rectify some things and they've got some new designs on
the studs where basically the o-ring that seals at the back of the block in the front of the engine
is actually there's like a o-ring groove recessed into the stud to account for that kind of
you know expansion that can occur. What about expansion in terms of your side clearance between
the rotor and the side plates? I don't think that that's an issue. I guess the factory rotor
housings from Mazda are aluminium cast aluminium anyway so you know maybe we're not talking too
dissimilar to the thermal expansion coefficient I just don't know about that. I mean there is
one little weird thing that I'm not really sure the answer to this but there was a gentleman who
did a four rotor and he used a peripheral port design and he had like a hybrid engine where he
had some iron plates and then he had some billet plates in the engine as well and I can't remember
which were which. I think it was like the inner two intermediate plates were billet and the outside
plates were iron and so on the iron plates he had to use the you know the liquid metal to block
off the porting and on the inner plates they were just machine completely flat there were no side
ports okay and he claims that the engine like hurt itself like from thermal expansion or something
where basically the rotors were like pushing into those billet plates and wearing them out really
bad on the inserts like immediately on the dyno. Now I don't know because I didn't build the engine
and I don't really have a deep enough understanding know for certain but his his hypothesis was that
this is interesting when you look at the Mazda factory engines the four rotor peripheral ports
themselves when they take those blocks apart and you look at their plates they didn't just
make the plates like solid for the intermediate plates just solid like with the lacking of the
side port they still have like a false port to them so like the intake port is obviously blocked
off with the liquid metal but it still has like a little bit of a divot there so what he was suggesting
is that that false port has some sort of like it has like a meaning to it like there was a reason
why the factory engineers for the race cars still had that false port profile in there
and so when we made the inserts on this engine we made sure that they weren't just completely flat
that they actually had a CNC like false port that was of the same depth of what it would look like
if you had epoxied the internal of an engine that was an iron engine to make sure that there was a
little bit of relief there for maybe the corner seal side seal coming around because there is no
side port there in case there was something weird going on I don't really fully understand the
mechanics of it but we just did that and everything seems to be working great I mean we got lots
hours on the engine and I beat the crap out of it on the dyno so we'll see I mean fingers crossed
so yeah it sounds like it's doing everything right probably a discussion around rotary engines
wouldn't be complete without talking about apex seals and I think this is an area where just
everyone has their opinion it's really difficult if you're forum surfing to get a consensus opinion
what is best so let's hear your take on the situation I don't have a lot of experience
with trying different seals on multiple engines my take on it is that the stock seal is probably a
really good seal for longevity because it's really hard but the risk with the stock seal is that if
you take it too far it'll shatter and it'll wipe out your engine it'll ruin your side plates your
rotor housings and it'll go through your turbocharger and so unless you're really good with your tune
and you know exactly what you're doing then if you're going to be experimenting with higher power
higher boost in racing especially if you're going to spend a lot of money on a three rotor or four
rotor then it's probably best to use an aftermarket apex seal and a lot of times these get criticized
for being banana seals or warping because they're softer but the thing is if you go too far and
you hurt the engine generally all that happens is you lose compression because you warp the seal
and you can just take it apart and put new seals in it and put it back together maybe scrub the
rotor housings down a bit and you're good to go as opposed to having a catastrophic failure
whereas the end all be all would be to have ceramic apex seals which are going to be just
like the stock seals in that they're going to last longer but they're going to last way longer
and have way less wear on the engine however again those can also be dangerous in a turbo
charge application if you're not you know right on top of the game and you make a mistake so given
the fact that there's always the potential for fuel starvation you know going around a corner
or some kind of failure in your fuel pump and having a lean event that you know maybe the
engine can't catch quick enough with the fail safes I think that I'm always in support of using
an apex seal that is quote unquote the banana seal and just be extremely conservative to not
get them so hot to bend them and that's just kind of that's kind of my theory on it I don't think
there's any given brand I think they're all good I used goopy apex seals in the forwarder I'm using
ENJ apex seals on this car and you know I hear a bunch of stories between all these different
brands but there's no like consistency between these stories so yeah that I think is is probably
the issue that I come across uh yeah so I think how I kind of see the uh the aftermarket apex
seals with the banana problem that you mentioned uh yeah I mean it's obviously a pain in the ass
you've got to pull the engine apart and and fit new apex seals but it's much cheaper than replacing
your rotor housings your rotor your turbochar basically everything in the path of destruction
so I think yeah that there's kind of a it's kind of a no brainer I haven't even ever had
experienced myself with ceramic apex seals but my take on that had always been from what I've read
and what I've heard from other rotary engine builders is stay away from those in a turbocharged
engine which kind of matches what you've just told us in terms of some of the aftermarket apex
seals I guess some of the horror stories I hear about is wear rates they can be very abrasive
sometimes to the rotor housing so yep your apex seal's not going to break but you know you pull
the engine apart after a thousand miles of use and the rotor housings are pretty much trash
have you seen that or not in your experience I don't I have not seen that but I don't daily
drive my car so I haven't put that many miles on them to notice that kind of issue but like the
first iteration of the four rotor I had quite a bit of miles on that and tore it down and the
rotor housings weren't damaged at all it was just you know issues with the engine that were unrelated
to the apex seals so I've never really seen that issue but I also premixed the engine pretty heavily
I mean I run closer to two ounces per gallon of premix and I think the quality of premix that you
use especially for alcohol if you're going to use ethanol I think that's where you're really
going to chew up your apex seals is if you don't have an oil that is made to suspend an alcohol
properly if it falls out of the suspension then you're going to have issues so that's a good point
in terms of the premix ratio because again this is everyone you ask about premix ratios has their own
kind of take on what's right. How I see it is sure okay we add more premix and that's going
to be beneficial for keeping everything lubricated and in good running order but also this is being
mixed as its name would suggest with the fuel so we're also combusting oil which in general
will degrade the octane of the combustion charge hence putting us potentially closer to
knock is this a real concern or is more simply better when it comes to premix I mean obviously
there's a limit to that. Yeah I think more is simply better I don't think that we're dealing
with such ratios like a two stroke engine where you're actually going to notice that much of a
difference in your your knock limit like the dilution of the amount of fuel with with oil to the
engine I've never really noticed such a thing I mean maybe you need to run it slightly richer if
you're going to mix it three ounces per gallon but somewhere around one and a half to two ounces
per gallon maybe if you're going to go to the track you go a little heavier I think the most
important thing though that's often under looked is to make sure that you have enough fuel in on
deceleration a lot of guys that do not have an oil metering pump will warp their apex sails without
realizing it when you go to the racetrack and I'm talking circuit track racing because all the
deceleration on a real circuit track as opposed to you know normal driving around and when you're
screaming back down from 9000 rpm and you don't have enough lubrication because you're doing a
fuel cut I think that's where you can run into some trouble too so I think just make some heavy
and it'll smoke on the warm up and then once you get them up to oil temp and the smoke usually goes
away I'm glad that you I'm glad that you raised the overrun fuel cup because you're absolutely
right it's another real easy one to overlook if you're coming from the piston tuning world but
most serious rotary engine builds are going to ditch the oil metering pump and move to premix
and then you sort of have to join the dots that hey if I'm not injecting fuel I've got no lubrication
inside of that engine so yeah pretty important to keep it fairly healthy on overrun I believe.
Yeah also just ensuring that you have really good fuel pressure, I mean a lot of times people
look at their fuel pressure and are like yeah it's good but you need to make sure it's good
in boost you know when all the amperage is being drawn from your alternator and your fuel system
I think that's probably the number one contributor to failures on 13Bs. 13Bs you don't really have
to worry too much about the oil system because it's pretty robust from the factory for what it is
I think the biggest attention needs to be to the fuel system setup and I see a lot of people run
surge tanks and a lot of times on these surge tank setups they're great except for long duration
use because when you're driving the car for a long time you'll actually get a cavitation from the
amount of heat returning to the surge so I think it's really important that you manage your return
flow if you're running a small like surge tank type deal even on any system I think you should
manage your return flow and potentially pulse width modulate your pump something like that.
What I do on my cars is because it's a rotary and there's so much money invested I use a mechanical
fuel pump that's cable driven off the back of the oil pump and so that ensures that I'm always
going to have fuel pressure and then it also doubles as a failsafe because if the cable breaks
well then the engine dies right and then also if the belt breaks for the oil system well then the
engine dies right because it's all driven from the same circuit the fuel and the oil so and that
also allows you to run a really high base pressure have really good atomization and not have to use
more stages on injectors which limits your risk and it also allows you to get a better tune with
that higher atomization from the higher fuel pressure so I like to run a 90 psi base which
seems crazy but it literally it doesn't care like it there's no issues like there's no
draw or horsepower loss or anything from that you know. Well I mean as soon as you move to a
mechanical pump yeah you're no longer sort of linking current draw to to fuel pressure so yeah
I totally get that. 80 plus psi is not sort of unheard of in drag racing engines with mechanical
pumps but you genuinely see a benefit when you're on the dyno going from let's say 3 bar 45 psi
which would be a typical typical base pressure up to that 80 psi. Yep sure exactly yep. Is there
any downsides though so as we increase that base fuel pressure one of the, let me just say it's a
problem but one of the aspects that we'll see with the injectors is that the injector dead time
will increase. Physically it's harder to open the injector against 80 psi of fuel pressure
than it is against 45 psi but no no issues from from that as long as you've got your dead time
values set correctly in the ECU. Yeah I mean I've seen some variation in what the VE table looks like
between the last car and this car despite using the exact same dead times and the exact same fuel
pressure and the exact same injectors it's hard to know exactly why maybe it's differences in
the porting and things like that but generally I don't worry too much about the dead times in my
opinion that just kind of reflects what your VE table is going to look like so maybe if you're
tuning a lot of cars then you want to be really consistent on that so that you know that your
VE table is you know synonymous to another car but I just make the VE table what it needs to be to
get the fuel that I'm looking for and after that it seems to seems to be fine so no issues really.
I think the the dead time I mean I've probably gone down a bit of a rabbit hole here so I'll
pull it back from that and sort of state that the dead time I think a lot of people probably do put
maybe too much emphasis on yes I think it's important if I've got the option I'm absolutely
going to be using injectors with no dead time so I can enter all of the data correctly in the ECU.
I have to also think back to when I first started tuning on one of the early
link ECUs that was available here in New Zealand, they had no dead time correction at all, it was
just ignored and I could still make the engine run and it would still tune. Yeah you'd start
getting some variation in the air fuel ratio particularly at idle where the dead time comes
a bigger aspect, a bigger percentage of the actual overall pulse width being delivered to the injector.
The part that most people ignore though is if you're not correctly accounting for dead time what
it will mean is your compensations that the ECUs are providing over and above those background
compensations for things like intake air temperature for manifold pressure, there's going to be an
error in those corrections so you'll start to see that creep in and yes you can bake in fixes for
manifold pressure inside of the V table but you know if your dead time is massively off then you
will see maybe your intake air temp correction is not going to do quite what you thought it was
going to do. Is it the end of the world? Absolutely not but it does happen. I just learned something
today, I did not know that, that's really interesting. We'll send you an invoice.
The other thing too is injector timing. Oh yeah actually I wanted to jump into injector
timing too, yes. How important is that for a rotary engine? Yeah so I think it depends on the
application but you know one thing I've noticed it doesn't really seem to make that much of a
difference at higher power. Now I don't know if that's because I'm already using up so much duty
cycle that there's not as much available window to actually perceive a difference but I do notice
that on specifically this peripheral port motors is that at low rpm and cruising injector time can
make a really big difference. Looking at the end of injection period I find that pulling it way back
from what you would expect on a side port engine the air fuel ratios actually get a lot richer so
I actually run a very like way retarded injector timing at you know the lower loads as it seems
to make the engine more efficient on air fuel consumption of fuel and also it seems to help
with some of that like brapping and bucking sort of situation but it's something I need to experiment
more. If I had a low dyno I'd love to be able to just sit there and play with it but that is one
of the benefits of having the higher fuel pressure is because there's kind of this like when you've
got an engine that's using a lot of fuel especially like E85 and you want to be able to go back to
93 there's it's not so much of an issue today as it was in the older days because the injector is
flow rates for idle and drivability but being able to run a really high fuel pressure on a
really small injector gives you a really wide range to be able to have really good atomization
at low operating load because you got a smaller injector so like on this fire rotor I only have
1,000 cc injector on the primary but I can get a lot of fuel out of that 1,000 cc and therefore
because there's not a lot of duty cycle in it because the high the base pressure well now
the injector timing seems to have more of an effect on you know the tune than it would have
otherwise on that same size injector at a smaller base pressure and then if I had gone to a 2,600
cc injector well then it'd be hard to get the car to idle and drive correctly on 93 octane where
you're using a less pulse rate. I hope that makes sense what I just said I think I'm correct so
yeah I think first I want to come back to your first point people I think put too much emphasis
on injector timing at high rpm high load and I mean if you're running a typically sized injector
and you're seeing maybe 75 to 85 percent maximum injector duty cycle well if you actually think
about what that means the injector is open for let's say 85 percent of the engine cycle at that
point clearly moving the timing around is not going to be achieving much it's basically open
almost all of the time anyway. So the gains or changes we will see are usually always down in
the idle and sort of that low rpm area where your duty cycle's so low so you actually can
move it around a little bit. I think when you've kind of touched on it there like I will move it
around and look for the air fuel ratio to move richer for a given fixed fueling pulse width
and if I'm going richer generally that means that the engine is therefore able to use more of
the fuel that's being injected so I tend to find at that point I am moving in the right direction.
Now David I am going to have to cut us off here we're running just a little long on time so I do
want to respect your time and I feel like we're probably going to need to have a follow up
episode at some point because I've touched on about half of what I had on my list.
Oh I'd love to, I love it, that's awesome. But unfortunately I also do, I do have to get
out of here so we've got the same three questions we ask all of our guests at the end
and the first of those is what's next in the future for you? More cars, more builds?
I would love to make my say formula supercars that's my dream is to make cars that people can buy
that are like this but more of a streetable car maybe with different options not so aggressive and
AC power steering that kind of thing I'd like to have my own line of cars that people can purchase
man and have some five rotor symphony sounds screaming around that's what I'd love to be
able to do. We'll see where the future goes other than that just experimenting and I'm going to try
to put a larger turbocharger on we're going to upgrade the compressor wheel on this turbo
and see if we can improve the torque curve. I do think that we're running out of compressor
wheel based on laser speed we could talk about that later but that's the next experiment on the
list. Sure I guess that's the great thing there's always something new to try. I'm definitely
here for it if you start building supercars though. Next question is there any advice you'd
give to a younger version of yourself to help reach where you are today in your career faster?
Oh my god that could be a three hour answer but yeah probably the most important thing would be
to trust in those solitude moments where you're dreaming and your it's constructive daydreaming
like running through different you know like if I'm on an airplane or I'm in the car you know
instead of listening to music just think about the fuel system that you want think about the
ignition system that you want even if it's not possible and you don't have the money
at the time you can't see how it's going to work don't focus so much on being so outcome dependent
just and focus on enjoying like the imagination because I think that's what has always opened
doors for me is whenever I had just been focused on the present moment and you know done things for
the experimental aspect because when you identify with seeking the knowledge then you're always
winning it doesn't matter if something breaks or something succeeds you're still always winning
because you're doing it for the information you're doing it to learn so like going into this
five-rotor there was a ton of uncertainty and there's a lot of sleepless nights because I you
know I'm like I don't know if this is going to work and I'm spending all this money and all this
time and you know there's a lot of anxiety and so to a younger person that feels that same kind
of anxiety they want to do that engine swap and they've never you know done such a thing and they're
going to spend so much money and don't worry so much about the uncertainty take it on with pride
that you're going to load yourself down with this challenge because you're going to learn something
from that and that's the point and there are no failures every anytime you fail at anything
anytime anything blows up there's two ways to look at it you go oh my god the transmission
broke this is so terrible or you can look at it and say I'm so glad I didn't get hurt you know and
that's the way that's what I would have told my younger self especially chasing girls so
I've got the greatest girlfriend in my life now and it was because I you know I just you know she's
the greatest person on earth she's helped me so much in this project she's an engineer too and
I think that you know that came into my life because I just got into this zone of just you
know working on myself and appreciating solitude instead of fearing being alone I think that's the
most important thing if you're young and you want to get into cars is you're going to spend a lot of
time alone you're going to be grinding and don't worry so much about what other people think and
don't chase people chase your goals that's that's it man right there and I think if you want to
achieve anything great that sort of breaks the pattern of the norm you therefore have to do
things in a different way to how most people do it so I guess that kind of sums up pretty much
what you've you've just given us there our last question for today David if people want to follow
you and see what you're up to how they're best to do so drop us your your social media channels
yeah sure um I would love if you'd like to follow me it's matse formula ma zz e i formula and you
can find me on instagram and youtube and also on facebook David Zachary matse and I love you know
I love answering questions just send me a dm and hopefully I can see it and get back to you as soon
as possible. Amazing and as usual we'll put links to those accounts in the show notes. Look David
as I mentioned literally could have probably gone another two hours I feel like I've just
scratched the surface here but amazing to get some more insight into everything you're doing and
particularly your philosophy around rotary tuning this information is just so hard to find from
people who genuinely have runs on the board so congratulations on everything you're doing and
we look forward to seeing what comes next. Well thank you so much for your interest in my work I
really appreciate the shout out and the opportunity here this is a really great platform and I'm
really happy that you're doing this and especially all the classes and all the information that you
offer this is the best thing that's what everybody needs so thank you so much. Appreciate it. Yeah man
have a good one. I hope you've enjoyed this episode of Tundin and don't forget by using the code
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