Sam from CWI Performance discusses their ambitious project of transforming a Fox Body Mustang into a 1000hp street car for the Optimus Streetcar Challenge. The episode dives into the technical details of their engine swap, featuring the Ford Gatzilla 7.3L V8, and the modifications made to optimize it for racing. Key topics include the choice of a centrifugal supercharger, custom intake manifold, and advanced tuning techniques using EGT sensors. Listeners will gain insights into the challenges and innovations involved in building a high-performance street car.
With 450hp to 1000hp on tap via an EMtron ECU control strategy incorporating a drive-by-wire (DBW) throttle body, this V8 swapped Fox Boy Mustang, an exciting project we couldn't resist chatting about.
Sam Hiu Bin of CWI Performance runs us through this 7.3L V8 Mustang build that has taken the Ford 'Godzilla' V8, never designed for race cars, and put it in a race car anyway. Not only that, but the team has also added a ProCharger centrifugal supercharger to ramp up the output in a compact package. It is as compact as a 7.3L V8 shoehorned into a Fox Body Mustang can be, anyway.
The biggest physical challenge with the Ford Godzilla for a swap like this is the height, but teamed with Indy Power Products, the oil pump has been moved so that a smaller wet sump setup can be used, allowing the engine to be mounted lower in the chassis. The CWI Performance 3-piece billet intake manifold also helps reduce the height at the top of the engine and incorporates a 1400hp capable C&R / PWR intercooler core to further improve packaging options as well as options to fit a 105mm or smaller LS throttle body or a Ford Coyote/Godzilla flavour too.
Boost-wise, the car produces 450whp at around 2pi, with it only taking 15psi to get it over 1000whp and the EMtron package also takes care of exhaust gas temperature (EGT) monitoring for both tuning and engine health functions. Even using an E90 ethanol blend, the car does see some knock/detonation, partly thanks to its 10.5:1 compression ratio, but the dual bank knock control takes care of this when the temperatures get high enough for it to start occurring.
"...hanol with a modest amount of boost pressure, and E90 is not even a consideration for this engine or no..."
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The Optimus Streetcar Challenge has a really eclectic mix of cars involved, and we're here with Sam from CWI Performance to talk about this Foxbody Mustang that's behind me.
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First of all, before we get into the car itself, could you give us a really sort of quick overview of what the Optimus Streetcar Challenge is all about?
What disciplines are tested?
So the Ultimate Streetcar Challenge is, I would say, a true testament to building a street car.
You have all kinds of people from all different places, all different kinds of businesses in here.
It's a multidisciplinary event.
You have autocross, road race, you have what we call the speed stop, which is sort of like a drag race mix with a U-turn sort of deal, and then you also have scoring for design and engineering, which is basically how many modifications you've done to the car while still being able to keep it streetable.
OK, so on that basis, with all of those disciplines in consideration, why did you decide the Fox Body?
Mustang was a worthy platform to start developing?
Well, cwi Performance has a long history of being involved in forts.
Last year we won the truck category with a C10 Chevrolet, so we're able to use different platforms and achieve different things.
So this year we kind of wanted to go back to the roots and use a Ford, and the Mustang is just iconic.
For sure.
Now you've gone ahead and performed an engine swap with this, which is probably one of the key elements.
So obviously a lot of power is going to be essential for most of those elements you just talked about.
What is the engine you've gone with?
So we have chosen the Ford Gatzilla 7.3
liter or 445 cubic inch engine, and we have done so because it's relatively new and we were interested in trying to keep something that's seen period correct for the car, using something similar to what was used in the 80s.
And we are also involved with several companies, one of those being Indie Power Products, who has a lot of experience, being in the engineering department of Roush for several years, and so they reached out to us.
They wanted us to machine parts for them because they wanted to develop this engine into a more race ready application.
So in stock form this is essentially a crate engine for the performance aftermarket.
It is a naturally aspirated engine as it's designed high compression, I assume.
It's about 10.5
to 1 compression and it's originally designed to go in the F250, f350 and cargo vans on the E250 and E350 as well.
So it's supposed to be a very robust, stout, reliable VA towing package essentially, and we've kind of gone into just trying to make it a race car engine.
OK.
So the requirements for the intended application a truck, towing, et cetera.
On face value, I'd assume, very different to what you're trying to do.
Normally that style of engine would be designed with a cam and inlet manifold design really to optimize low RPM torque, obviously ideal for towing.
If you made any changes to the cam, obviously inlet manifold is bespoke there to re-engineer the RPM range that the power is being made to suit what you're doing now.
Correct.
So we've changed the cam, we've locked out the VCT.
That comes from the factory and one of the biggest changes I would say that we've made to be able to fit the package inside a lowered car like this one is, which is about 2 inches from the ground at right height.
We have the package that any power products design and engineer, that we produce in-house, which essentially changes the oiling system completely and it makes it a much more compact package.
Vertically speaking From the factory, this engine has the oil pump in the sump and it's a really, really tall package because it's designed to go into a lot of right clearance on a truck.
So we found just test fitting it with one of the low profile oil pans at the right height that we had the car.
It just wouldn't fit.
It would have been a pretty dangerous deal and instead of just going straight to the dry sump we wanted to actually torture, test the products that we're making and we're using the car for R&D in that sense.
Okay, so just for clarity there not dry sump, it's still a wet sump, but a lower profile sump and maybe a relocated oil pump.
Is that what you're sort of saying there?
Yes, so the oil pump has been relocated to behind the front cover.
As you would see, on an LS engine it's still chain driven, but it's really push forward and up.
It has a rail between the sump and the block which basically adapts all the factory oiling orifices in the engine to our oiling system that IndiePower products designed.
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OK, let's move on to the obvious element here in terms of a power adder, which is the fairly sizeable pro charger sitting in the engine bay.
Now again, this engine designed for naturally aspirated use 10.5
to 1 compression.
I mean it's not out of the ballpark, but that's quite high in terms of compression for a supercharged or turbocharged engine.
Did you retain that compression ratio and just rely on a really good quality fuel?
Yes, so we have kept the same compression ratio.
The engine has forged pistons and rods in it, but we kept the 10.5
compression ratio because we wanted to keep the pep of it but we also wanted to add power.
So in my experience in tuning we have had really good success with using ethanol based fuels for higher compression and boosted applications.
So we went with a about 90% ethanol fuel from Ignite Racing and that has even so far it's been phenomenal.
I'm interested just the thought process on the decision around the pro charger or centrifugal supercharger, just to sort of be a little clearer versus maybe twin turbos or a single turbo versus maybe a screw style blower in the valley.
What was the driving decision there that made the pro charger the winner?
So it was a series of decisions.
The main one was trying to get more power out of something that ideally provided us the most reliability with the less fuzz the least amount of fuzz.
So we decided to go with the pro charger.
We reached out to pro charger and we told them what we wanted to do.
They recommended us the current unit that's in the car, which is a F1A94mm.
We didn't go with turbos because of the added complexity of running the exhaust plumbing and all that stuff.
The engine bay is already pretty packed on the car so, having turned manifolds and downpipes and all that stuff would have been would have added a lot of complexity and more failure points.
So we opted to go with the centrifugal style because we also wanted to start developing our own parts for the application.
So the engine currently has our intake manifold on it and that intake manifold has a built-in PWR core that's rated for about 1500 horsepower and currently it's.
We've been testing the intake manifold using a multitude of sensors, like intake temperature sensors and pressure sensors, to determine what the efficiency of the intake manifold is and so far it's been really, really good.
Okay, now one of the pros and the cons, I guess, with a centrifugal supercharger, like the pro charger, is that the boost pressure is really set by the ratio between the driven and drive pulleys on that setup, and obviously you can change those, but not on the fly.
So once you sort of get the car to the track, the boost is set.
Now you've got quite a novel approach for actually giving the driver a little control over that with this drive by white throttle body.
So how's that work and how's that integrated with the electronics package?
So currently we're using an Mtron KV80CU which has dual drive by wire control on it, and in talking with the guys at Mtron I kind of reached out to them and I gave them the idea that I had about essentially cold gating the centrifugal supercharger, which is a more commonly found application on a turbocharged vehicle, to reduce surge or eliminate surge altogether.
But in this case I had the idea of just testing out to see if this situation would work, and it turned out to work really well.
And essentially what we're doing is we're bleeding off the boost that the supercharger otherwise produced in order to regulate power.
So by opening the throttle body at different throttle angles we have a different amounts of bleed off, so we can run the engine from anywhere from about 450 wheel horsepower to 1,018 wheel horsepower.
That's a fairly decent range and obviously with this sort of use of the vehicle that makes a lot of sense In terms of the boost pressure that the engine sees when you've got that thing fully open or at the most open position 450 horse as you mentioned is it seeing any positive pressure in the inlet manifold or is that back to ambient?
Well, it's actually kind of amazing because the supercharger flows so much volume of air that it still sees about 15 kPa, which is about two pounds of boost.
So not much, but a little bit, just a little bit.
And when you're all in there, 1,000 plus wheel horsepower, what sort of boost does it take to produce that?
At about 7,000 RPM, which is close to where we have the rev limiter set to.
It sees about 15 psi of boost pressure.
Okay, so not actually a huge amount of boost.
Obviously, you do have a lot of capacity on your side there with 7.3
litres.
Now, in terms of the electronics package, you've mentioned the Mtron KV8 ECU.
There I noticed that the engine is also equipped with individual exhaust gas temperature sensors.
Are they an input to the KV8 as well?
What are you using those for?
Is it individual cylinder tuning or just logging?
Yeah, what are those there for?
So we're using, as part of the electronics package, we are using the Mtron EGT controllers and we're using those for, first of all, monitoring engine efficiency, monitoring EGTs, make sure that the tuning is safe, timing is safe and all that stuff, making sure that we have all cylinders firing evenly and we don't have any cylinders that are misfiring or maybe a dead cylinder or something like that.
That's actually something that's easy to overlook.
I mean, most people think that EGT sensors are there for individual cylinder fuel trimming, which absolutely they can be used for.
But a really convenient upshot of this is, if you're chasing a misfire conventionally, that's really frustrating.
You know you've got a mis, don't necessarily know which cylinder it's on, but the EGT, you'll see that individual cylinder straight away start to go cold.
So it really helps you sort of zero in on where that issue actually is Interested in terms of the data logging and data analysis.
So you're doing anything with that side of things to help improve the car, the engine, tuning the package from one run, one event to another.
So essentially the big bulk of using the EGTs.
As far as tuning was, during the dyno tuning sessions I was able to tell whether the ignition timing that I was using in the engine was either too retarded or too advanced, based on just the engine exhaust gas temperatures.
We found that running timing that essentially I thought would be right, you know, ballparking the engine it was the first one of these engines that I've ever tuned.
Just going off of the science piston size, compression, all that stuff we kind of went with no numbers and we found that the EGTs were actually really high.
So we started adding a couple degrees of timing in at a time and the engine just kept picking power up.
It went from about 850 to 1,018 with just a few more degrees of timing, and I was able to do that thanks to having the data from the EGTs.
Coming back to that element with the timing.
Obviously this is a bit of a trade off, particularly with high compression like you've got there.
However, you are on a really good fuel with that 90% ethanol with a modest amount of boost pressure, and E90 is not even a consideration for this engine or not a problem at all.
It is when it is on full tilt and the engine is running hot.
So, essentially, when you're out beating on it on the road course especially in bigger tracks like Road America, where we're getting wheel speeds of anywhere from 150 to 170 miles an hour you do see the EGTs creep up a little bit.
And even with such high octane fuel and the cooling aspects that ethanol fuels have, you do still see knock.
The Amtron, however, has a really, really good knock control system built into it and we're using dual bank knock control.
Perfect, alright, sam.
We know the car is heading out on track again soon, so we appreciate your time.
We'll leave it there, but thanks for giving us some insight into the car and we wish you guys all the best for the rest of the event.
Thank you.
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