Oil Burners: The Improbably Awesome History of Cummins At The Indy 500

The Indy 500 (the Indianapolis 500) is a premier American open-wheel race held at Indianapolis Motor Speedway. Because it’s so competitive and rule-driven, it’s a major proving ground for engine and engineering innovations.

Cummins is an engine company best known for diesel powertrains used in trucks and industrial equipment. In this episode, the host focuses on Cummins’ racing involvement at the Indy 500 and how its diesel work influenced later race-car development.

“Qualified on the pole” means the car set the fastest time in qualifying and starts first on the grid. Pole position is valuable because it reduces traffic risk at the start and gives the leading car cleaner air and track position.

Diesel engines use compression ignition: air is compressed until it gets hot enough to ignite the fuel without spark plugs. In racing, diesel’s combustion characteristics can affect power delivery, efficiency, and durability compared with gasoline engines.

In engine development, “power” is how much output the engine can produce, “refinement” is how smoothly and consistently it runs, and “durability” is how long it can last under stress. The host uses these as the key performance dimensions that separated early diesel racing attempts from later ones.

“Bore” is the cylinder diameter and “stroke” is how far the piston travels in the cylinder. Together they largely determine engine displacement and how an engine’s power and torque characteristics tend to behave.

In this context, “blowers” refers to forced-induction superchargers that compress intake air before it enters the engine. More compressed air allows more fuel to be burned, which can increase power output.

Ray Haroon is credited in the segment as the winner of the first Indy 500. The host uses him as a starting point for the episode’s long arc toward Cummins’ later racing involvement.

Marmin is mentioned as the factory/organization that employed Klessy Cummins and fielded the race car from the factory. In this segment it functions as the early industrial link between manufacturing work and racing participation.

William Irwin is described here as the wealthy backer who funded Cummins’ early development and absorbed losses while the company struggled through failed ideas and slow progress. The segment frames him as a practical counterweight to the engineering vision driving the company.

Fuel metering is the process of precisely measuring and controlling how much fuel a diesel engine injects. In early diesels, getting fuel metering right was a major challenge because it directly affected combustion quality and engine stability.

Needle valves are precision valves used to regulate diesel fuel flow for metering and injection. The segment notes that these valves would seal in a seat, which matters because a tight seal helps prevent leaks and keeps fuel delivery consistent.

A mechanically controlled direct injection system is a diesel fuel setup where fuel is injected directly into the combustion chamber using mechanical components (rather than electronic control). That control affects how precisely the fuel pressure and timing are managed, which in turn changes atomization and combustion efficiency.

A pre-combustion chamber is a smaller auxiliary chamber used in older diesel designs to help start combustion. Fuel injected into that area relies on the chamber’s mixing and turbulence before the main combustion happens, which can limit how efficiently thicker fuel can be atomized.

Atomizing is breaking liquid fuel into a fine mist so it mixes with air more effectively. In diesel engines, better atomization generally improves combustion completeness and reduces soot and unburned fuel.

Pressure lubrication (often called pressure-fed lubrication) uses an oil pump to send pressurized oil to engine bearings and moving parts. This helps maintain a consistent oil film under load, improving durability compared with simpler splash or gravity-fed lubrication approaches.

Reciprocating parts are components that move back and forth (like pistons and related mechanisms). In engines, enclosing these parts can reduce exposure to oil/air contamination and improve packaging and reliability.

The 1925 Packard touring car is used here as a real-world example of an automobile Cummins wanted to power. Packard was a major luxury brand in the 1920s, and referencing a specific touring car helps anchor the story in the kinds of cars diesel was being aimed at.

The New York Auto Show is a major North American event where automakers and suppliers debut vehicles and technologies to the public and press. In this segment, it’s central because the car was displayed across the street after the promoter wasn’t allowed in.

K-Don is identified in the segment as a speed-seeking British figure who planned to run on Daytona’s beaches to chase the world land speed record. The podcast uses him as the next connection point for Cummins’ diesel publicity.

Daytona is referenced as the location for an attempt at the world land speed record on the beaches. The segment treats it as a high-profile proving ground where an engine’s real-world output and fuel economy could be showcased.

The Cummins Model U is an early Cummins diesel engine that the episode credits with strong fuel-economy and adequate power for its era. In the segment, it becomes the basis for retrofitting a truck fleet, which helps Cummins gain traction in trucking.

Indianapolis Motor Speedway (often shortened to Indy) is the famous oval track that hosts the Indy 500. The segment ties Cummins’ return to Indy to rule changes that allowed stock-production engines, shaping the race strategy.

Eddie Rickenbacker is described as the owner of the track who changed the Indy 500 rules. In this segment, his rule change allowed stock production block engines, which opened the door for Cummins to build a qualifying engine-based racer.

“Stock production block engines” means engines built from production (mass-market) engine blocks rather than purpose-built racing-only blocks. The rule change mattered because it made it possible for a company like Cummins to compete using a modified version of a real production design.

A displacement limit is a cap on engine size, measured as the total volume swept by the pistons (in cubic inches here). The segment says Indy limited displacement to 366 cubic inches, and Cummins aimed to modify the Model U to reach that size.

Qualifying runs are timed attempts before the main race that determine whether a car earns a starting position. The segment says Cummins’ entry had to make more than 80 miles per hour in qualifying to get a guaranteed spot.

Heavier duty springs are stiffer suspension springs designed to handle more weight and maintain ride height under load. The segment says the chassis was upgraded with heavier-duty springs because the engine was massive and the car was built around it.

Gabriel shocks are shock absorbers made by Gabriel, used to control suspension motion. “Dual” shocks means two shock units per corner (or per axle setup), which can help manage damping for a very heavy, engine-forward race car.

The 366 cubic inch limit is an Indy 500 engine displacement rule that caps how large the engine can be. Cummins had to redesign the engine to stay under that volume, which directly affects how much air/fuel the engine can move and therefore its potential power.

An inline four is an engine with four cylinders arranged in a single straight row. In this Cummins Indy setup, switching to an inline-four layout helped meet the displacement limit while keeping the diesel’s stroke characteristics.

RPM (revolutions per minute) is how fast the engine’s crankshaft spins. Diesel engines historically struggled to rev high, so the transcript’s emphasis on power “right of the RPM” and revving to 2000 RPM highlights how unusual the build was.

Compression ratio is the ratio between the cylinder volume when the piston is at its lowest point versus highest point. Diesel engines rely on high compression to ignite fuel, so compression ratio strongly influences combustion efficiency and how much power you can make.

Cylinder pressure is the pressure inside the combustion chamber during the compression/combustion process. Higher cylinder pressure generally supports stronger combustion in diesels, which is why the transcript compares it to modern diesel behavior.

A ram air setup uses the car’s forward motion to force more air into the intake system. The “ram” effect increases intake airflow and can improve combustion, especially at speed, which is why it mattered so much for this Indy diesel.

A ram tube scoop is a ducted intake design that captures high-velocity air and routes it directly toward the intake manifold. In this case, the scoop passed through the radiator to deliver a straight shot, aiming to increase effective charge and combustion quality.

The intake manifold is the air distribution chamber that routes air from the intake system to the engine’s cylinders. For a ram-air-fed diesel, how the manifold is fed affects airflow quality and therefore combustion and smoke levels.

Complete combustion means the fuel burns thoroughly, producing less unburned material. In diesel engines, incomplete combustion often shows up as visible smoke, so the reduction in smoke after adding the ram scoop is evidence the airflow improved combustion quality.

Columbus, Indiana is the location of Cummins’ base mentioned in the transcript. The detail matters because it explains how close the company was to the speedway and that they could test the car on public roads before/around race activity.

Miles per gallon (MPG) is a measure of fuel efficiency: how many miles you can drive per gallon of fuel. The segment uses an MPG figure to emphasize that the diesel’s efficiency was a key competitive advantage.

A “flying mile” is a speed-test format where the vehicle is already at speed when it enters the measured mile, so the time is recorded over that mile rather than from a standstill. It’s commonly used for land-speed records because it better reflects sustained top speed.

A slide rule is an analog calculating tool used before electronic calculators. In this context, it’s mentioned to highlight that the speed prediction was done with manual math rather than modern simulation or data logging.

The Indianapolis 500 (Indy 500) is a premier American open-wheel race held at Indianapolis Motor Speedway. This segment focuses on Cummins’ diesel-powered entry and how fuel economy and durability helped it succeed despite being far from the front at qualifying.

Dave Edwards is identified as the driver of car number 8 in the 1931 Indianapolis 500 for the Cummins diesel effort. In this segment, his role matters because the car’s race outcome is tied to consistent driving and avoiding trouble.

Thane Hauser is named as the “riding mechanic” for Dave Edwards’ 1931 Indy 500 car. A riding mechanic was a crew member who stayed with the driver during the race to handle mechanical issues and assist with repairs.

Qualifying speed is the fastest speed a car achieves during the qualifying session, which determines starting position. In this segment, the car’s qualifying speed is described as very low, making its later race finish more surprising.

Fuel economy is how efficiently an engine uses fuel to travel a given distance. In racing, it matters because fewer fuel stops can translate into more time on track and better overall finishing position.

Pit stops are scheduled stops in the pit lane to refuel, change tires, or perform repairs. The segment contrasts frequent pit stops by other cars with the Cummins car’s fuel-economy advantage.

“Combustion style” refers to how an engine’s fuel-air mixture is ignited and how the combustion process is managed. In this segment, Cummins is comparing different combustion approaches between the four-stroke and experimental two-stroke engines.

General Motors is referenced as the source of a successful two-stroke Detroit diesel example that influenced Cummins’ 1934 engine experiments. The key point is that Cummins was reacting to another company’s diesel technology direction.

A four-stroke engine completes its cycle in four piston movements: intake, compression, power, and exhaust. Cummins is described here as building a four-stroke diesel for the 1934 Indy effort, contrasted with an experimental two-stroke.

A two-stroke engine completes a power cycle in two piston movements, using porting (intake/exhaust passages) rather than separate intake/exhaust strokes. The transcript notes Cummins built an experimental two-stroke alongside a four-stroke for 1934.

Displacement is the total volume swept by all the engine’s pistons, commonly used to describe engine size. The transcript gives the target displacement (364 cubic inches) for both engines so listeners can compare the designs fairly.

“Square” bore and stroke means the cylinder diameter (bore) and piston travel (stroke) are the same or very close. That geometry affects how an engine breathes and how it tends to rev, and the transcript uses it to describe how Cummins arrived at the 4.875-inch bore and stroke dimensions.

A two-valve cylinder head uses two valves per cylinder—typically one intake and one exhaust. The transcript contrasts this “traditional two-valve cylinder head” on the four-stroke with the two-stroke’s different intake porting approach.

In this two-stroke design, intake ports are located in a sleeve, and the piston movement uncovers them as it travels. That porting strategy replaces the more conventional intake-valve timing used on the four-stroke engine.

Side-mounted camshafts place the cam(s) on the side of the engine block to operate the valve train. In this segment, both the four-stroke and two-stroke designs are described as using side-mounted camshafts to open the valves.

A supercharger is a forced-induction device that uses an engine-driven compressor to push more air into the cylinders. The segment quantifies how much horsepower the supercharger/blower consumed in four-stroke versus two-stroke diesel applications.

Scavenging is the process of clearing out exhaust gases from a cylinder and replacing them with fresh charge (air and fuel). In a two-stroke engine, scavenging is especially critical because the cycle is compressed into fewer strokes.

Dale Evans is named as the driver who qualified 22nd in the four-stroke car and later retired after a pit stop. In this segment, his race outcome is used to illustrate how the two- vs four-stroke diesel approach played out under racing stress.

The transmission is the drivetrain component that transfers engine power to the wheels, typically through gear ratios. The host says the diesel’s torque and aggressive pit-lane departure caused the transmission to fail.

Wild Bill Cummings is identified as the driver who went to Daytona in 1935 to attempt flying-mile speed runs. The segment uses these attempts to argue that diesel engines could achieve high speeds, even though the records were unofficial.

OE options means original-equipment options—engines supplied by a manufacturer to be installed by the vehicle maker as a factory choice. The segment says Cummins signed contracts so their engines could be offered directly by truck manufacturers.

A “clean sheet design” means engineers start from scratch instead of modifying an existing engine. That approach is often used when the requirements are so different that reworking the old design would be inefficient.

“Supercharged” means the engine uses a forced-induction system (a supercharger) to push more air into the cylinders. More air allows more fuel to be burned, which can raise power output compared with a naturally aspirated engine.

“JBS-600” is the specific designation for Cummins’ J-Series engine variant. In the transcript, “S” indicates it’s supercharged, and “600” is tied to the six-cylinder configuration.

An “inline 6” is an engine with six cylinders arranged in a single straight line. This layout is known for smooth power delivery because the firing order is naturally balanced compared with many other cylinder counts.

A “two-valve pushrod engine” uses two valves per cylinder (one intake, one exhaust) operated by pushrods. Pushrods transfer motion from the camshaft to the rocker arms, which is a common, durable valvetrain design in many engines.

“Torque” is the engine’s twisting force that helps accelerate a vehicle, especially at lower speeds. Peak torque at a lower rpm (like the 1400 rpm mentioned) usually means stronger pull without needing to rev as high.

A “100,000-mile guarantee” is a long coverage promise tied to how many miles the vehicle is driven. In this context it’s being used as a marketing/assurance tool to encourage truck manufacturers and buyers to adopt the new engine.

Spark ignition engines are gasoline-style engines that use a spark plug to ignite the air-fuel mixture. The transcript contrasts them with diesels, which rely on compression ignition instead of spark.

Naturally aspirated engines make their intake air flow without a turbocharger or supercharger. That means the engine’s power is limited by how much air it can draw in at atmospheric pressure.

A four-valve cylinder head uses four intake/exhaust valves per cylinder (instead of two), which can improve airflow. Better breathing helps high-rev engines make more power, especially when paired with forced induction like a supercharger.

Using aluminum in engine components can reduce weight and help manage heat, which is valuable when trying to rev higher. In this historical context, aluminum was “unheard of for diesels,” meaning it was a major materials shift for durability and speed.

“BMW P” appears to refer to a specific BMW racing engine or class reference used as a benchmark for power output. In this segment, it’s treated as the target performance number the diesel program needs to exceed.

The BMW 3 Series is a compact luxury sedan (and sometimes wagon) known for balancing everyday comfort with sporty performance. In a discussion about horsepower targets, it’s often brought up because its engines and tuning options can be used to reach specific power goals. That makes it a common reference point when someone is talking about what kind of performance a build or spec might need.

Fuel injection is the system that meters and sprays fuel into the engine cylinders (or intake) rather than using a carburetor. At very high RPM, the injection system must deliver the right amount of fuel precisely and repeatedly.

Connecting rods are the link between the pistons and the crankshaft, transmitting combustion force into crank rotation. Here they’re called out as “beefy” and strong enough (per the math) to survive 5400 rpm, which is critical for high-rpm diesel racing.

The valve train is the system that opens and closes the engine’s valves (including components like camshaft, lifters, and related parts). This segment notes it was capable of surviving 4000 rpm, meaning valve timing and motion control were a limiting factor in the design.

The JBS 600 is a specific Cummins Indy 500-era engine project referenced in this segment. It’s described as being tested on a dyno with a modified four-valve head to see whether the design could survive high-rpm operation.

Main bearings support the crankshaft inside the engine block and rely on an oil film to prevent metal-to-metal contact. The segment says the main bearings (and rod bearings) were grooved to improve oil delivery, because the high-rpm setup was burning up the bottom end.

Rod bearings sit in the big ends of the connecting rods and support the crankshaft journals. In this segment, grooving the rod bearings is presented as a solution to oiling problems that were causing dead engines during dyno testing.

SAE 10 refers to an oil viscosity grade—how thick or thin the oil is when it flows. The segment says SAE 10 was determined to be the needed oil weight and was used throughout, implying viscosity was tuned to maintain the oil film at high rpm.

An auxiliary motor-driven oil pump is an extra pump added to increase oil pressure and flow beyond what the engine’s standard system can provide. Here it boosts oil volume to 30 gallons per minute and helps keep oil pressure at 50 psi under full load.

“50 psi” is oil pressure measured in pounds per square inch. In this segment, maintaining 50 psi at full load is treated as essential to prevent bearing failures during high-rpm dyno runs.

A belt drive transmits rotational power from one component to another using a belt and pulleys. Here, the belt drive arrangement for the supercharger is blamed for damaging the front main bearing, so the team changes how the supercharger is driven.

A viscous dampener is a vibration-control device that uses fluid resistance to reduce oscillations. The segment says one is used at the end of the crank to stop vibration, which matters because high-speed rotating assemblies can develop damaging harmonics.

Wrist pins (also called piston pins) connect the piston to the connecting rod and allow the piston to pivot as it moves. The segment describes wrist pins splitting at high rpm, sometimes breaking pistons or rods—so the team changes the pin design to survive the loads.

A thicker-wall wrist pin increases material strength and stiffness to resist splitting under high rpm loads. The segment notes it adds rotating weight, but the team accepts that tradeoff because the alternative was repeated catastrophic failures.

Piston clearance is the designed gap between the piston and the cylinder wall. The segment gives specific clearance targets (55/10,000s modified to 95/10,000s), reflecting how engineers adjust fit to manage heat expansion and avoid scuffing or seizure at high combustion temperatures.

A cross-flow cylinder head routes intake and exhaust through different sides of the head, which can improve breathing. A “four-valve” setup uses two intake and two exhaust valves per cylinder, typically allowing better airflow than a two-valve design. In this segment, the host ties the Indy-era Cummins results to experimenting with this head layout.

Swirl is a rotational motion of the air in the combustion chamber that helps mix fuel and air and can improve combustion. Many engine designs aim for strong swirl and squish to promote faster, more complete burning. This segment highlights a surprising Indy-era result: they made more power with “no swirl” than with the conventional approach.

Squish is the rapid “squeezing” of air toward the center of the combustion chamber as the piston approaches top dead center. It increases turbulence and can improve combustion quality. The segment notes Cummins had “almost no squish” yet still increased power, contradicting common assumptions for diesel combustion.

In a diesel, the injector pump cam is part of the mechanism that drives the fuel pump plunger(s), controlling when and how much fuel is pressurized and delivered. Reworking the cam changes the timing and characteristics of injection. The segment says Cummins modified the cam to match their race combustion strategy.

Injection timing is the crankshaft position (or time relative to piston movement) when the diesel fuel is injected. Advancing or retarding timing changes combustion phasing, affecting power, noise, and engine stress. The segment emphasizes that their race setup ended up with timing matching a lower-speed stock application after testing “10 degrees slow” and “12 degrees fast.”

Valve float happens when the engine speed is high enough that the valve train can’t keep the valves following the cam profile, so the valves lose control. This can cause power loss and, in severe cases, valve-to-piston contact. The segment says their piston/valve interference issue was “mostly because of valve float,” and they cured it with camshaft design and improved valve springs.

High-speed cameras capture motion at extremely high frame rates, letting engineers study fast events that are invisible to the naked eye. Here, the host says Cummins used them in 1949/1950 to monitor and review valve train function at 3000 frames per second. That’s an early example of using instrumentation to validate mechanical timing at racing RPMs.

An iron engine uses iron (typically cast iron) for major internal components like the block. Iron is heavier but can be easier to produce and robust for early development testing. The segment explains that because aluminum parts weren’t ready, they ran tests on an iron engine while tooling for aluminum components was being prepared.

Pushrod clearance is the controlled gap in a pushrod valve-train so the camshaft can actuate the valves correctly. As temperature rises, pushrods and the cylinder head/block expand differently, changing that gap. That’s why the engine was started with everything loosened and then adjusted at operating temperature.