Penske’s top-secret engine rules in 1994

Published On March 15, 2016 » 8139 Views» By Marshall Pruett » Blogs, IMS, IMS History, Indy 500

We’re chronicling 100 days of Indy 500 history on #SpeedRead leading up to the historic 100th Running. With 75 days to go, racing journalist Marshall Pruett continues his look back at milestone cars and technology.

More Pruett: The “Fantastic” Turbine | Murphy’s Miller straight-8 | Yunick’s winged Watson More 100 days

It came, it saw, it conquered.

1994’s Penske PC23-Mercedes-Benz stands on its own among devastating and demoralizing Indy 500 entries. The top-secret 209-cubic-inch Ilmor designed and built, Mercedes-Benz-badged 500I pushrod turbo V8 engine was the heart of the hell unleashed by Roger Penske on Indianapolis Motor Speedway in the hands of race-winner Al Unser Jr., Emerson Fittipaldi, and Paul Tracy.

The 1994 Indy 500, won by Al Unser Jr., bore the fruit of Roger Penske's creed "Effort equals success."

The 1994 Indy 500, won by Al Unser Jr., bore the fruit of Roger Penske’s creed “Effort equals success.”

It was a classic Penske move: A special engine that made far more power than its rivals mated to the best chassis with three of the best drivers in the field of 33. Altogether, only a crash (Fittipaldi) and a turbo failure (Tracy) kept “The Captain” from completing a 1-2-3 sweep of the 1994 Indy 500. Penske entries started first (Unser Jr.) and third (Fittipaldi), led 193 of 200 laps (Fittipaldi 145, Unser Jr. 48) and set a new standard for shock and awe as the musclebound PC23s flirted with the 250 mph barrier on the straights after sailing through the corners at impossible speeds.

As Jade Gurss chronicled in his excellent book “Beast,” which documents the Penske/Ilmor project, a shift in rules by Indy 500 sanctioning body USAC—and the eagle eyes of Ilmor founder Mario Illien and Paul Morgan—set the outcome of the 1994 race in motion.

“USAC redefined their rules for a pushrod engine with the clause 115-D. Some of the details remained static, but by eliminating the words ‘stock block,’ it allowed a special-built racing engine that would have a power advantage without the Achilles heel of a heavy and unreliable block from an assembly line,” Gurss wrote.

“It meant a designer could now add improvements that had been previously impossible, such as optimizing the camshaft location, shortening the pushrod length for more control, as well as maximizing cooling and increasing the structural strength of the engine. In a dramatic case of the law of unintended consequences, the new wording was like red flashing lights to the eyes of Illien and Morgan. It wasn’t an entirely new topic, as the subject had been discussed occasionally between the Penske team and Ilmor for several years, but the relaxed rules opened the door enough for Ilmor and Penske to kick it wide open.

Unser Jr. in the narrow, aerodynamic PC23 cockpit.

Unser Jr. in the narrow, aerodynamic PC23 cockpit.

“Paul and I were already convinced we had to do it, and quick,’ said Illien about building a pushrod engine for a single race. “There was no doubt about that. I was sure other [engine manufacturers] were thinking about it as well. We felt this was our one chance, and we had to do it.”

Under Ilmor’s guidance, the era’s standard of 850 horsepower from a non-pushrod Indy car V8 turbo was obliterated as the 500I hit 1024 horsepower on the dyno. It pulled away from its rivals with ease and created a clear separation between Penske’s trio and the other 30 cars and drivers that had no chance to compete. The great engine was used just once; USAC altered its rules immediately after the 1994 Indy 500 to remove any advantages the pushrod layout offered, and with those changes, crushing defeats due to technical superiority have been all but impossible to achieve.

If there’s one aspect of 1994’s race-winning package that has been under appreciated, it’s the sublime Penske PC23 chassis designed by Nigel Bennett. The PC23’s volcanic turbo V8 engine has been the primary talking point since Team Penske—then Penske Racing—obliterated the field, but it needed a chassis with superb aerodynamics and exceptional mechanical grip to turn its raw power into the beast that tied Indy’s four corners together in ways that were previously unimaginable.

Outside of Indy, the PC23 led Penske’s three drivers to 11 wins with the standard Ilmor V8 turbo, and with the 500 added in, the chassis carried Unser Jr. to the championship and the three Penske drivers to 12 victories—a staggering 75 percent win rate.

One car. One year. And complete ownership of Indy car racing and the Indy 500.

“Emerson recorded the best lap of the month, a 230.438 mph average,” Gurss wrote. “While the Speedway’s timing system showed a 244 mph speed at the start/finish line, the Penske data from the backstretch showed an amazing number: 252 mph! ‘Please don’t tell me what that is in kilometers,’ Fittipaldi demanded. ‘It will only scare me!’ Sorry Emmo, but that’s 405.6 kilometers per hour.”

What an amazing time.

The 500I, aka, the "Beast."

The 500I, aka, the “Beast.”

The size of the pushrod V8 turbo is clear, thanks to the wide, elongated engine cover.

The size of the pushrod V8 turbo is clear, thanks to the wide, elongated engine cover.

The PC23 uncovered.

The PC23 uncovered.

Thanks to the Penske PC23 chassis and its strong (standard) Ilmor engine, Roger's drivers swept the Portland podium.

Thanks to the Penske PC23 chassis and its strong (standard) Ilmor engine, Roger’s drivers swept the Portland podium.



About The Author

Marshall Pruett

Marshall Pruett transitioned from more than 20 years as an open-wheel and sports car mechanic, engineer and team manager into his current role as a writer and reporter in 2006. Follow him @MarshallPruett []

The speeds were not "impossible" in the corners. As the historical articles make clear, the car was actually a handful in the corners due to mid-corner to exit power understeer. The mid-corner understeer tendency was a basic issue with the car, made slightly worse by the higher cg of the pushrod engine. If the cars had handled better in the corners, they would have been a LOT faster than the opposition, instead of only 1-2 mph faster in qualifying. The engine delivered over 1000 bhp, which was 160 bph more than the quadcam engines. 

The car's weakness in the corners was shown dramatically in 1995, when, using what was basically the same design, equipped with the same quad-cam 2.65l engine as the rest of the field, none of the Penske drivers could extract enough speed from the car to qualify. I remember watching a video of one of the Penske cars in 1995, as it got into a lurid power slide exiting Turn 4, leaving long rubber streaks on the road as the car failed to generate enough grip to cope with the quadcam engine torque.