One engine. One race. One win...

[ZRX61]

Over dinner in Phoenix in 1993, Roger Penske asked Mario Illien one question: what would a purpose-built pushrod engine produce under the USAC rulebook's pushrod allowance? Illien answered: 940 HP minimum. Penske said build it. In total secrecy, in a warehouse near Penske Racing's headquarters in Reading, Pennsylvania that team members called "the Taj Mahal," Ilmor Engineering designed, built, and tested a turbocharged 3.43-liter pushrod V8 that would exploit the widest loophole in the history of American open-wheel racing. The USAC rulebook, intended to let production-based pushrod engines compete against exotic DOHC four-valve race engines, allowed pushrod engines 209 cubic inches of displacement (vs 162 for DOHC) and 55 inches of mercury turbocharger boost (vs 45 for DOHC). In 1991, USAC quietly dropped the requirement that pushrod blocks be production-derived. Nobody noticed except Ilmor.
The engine, internally designated Ilmor 265E and later badged as the Mercedes-Benz 500I after Mercedes provided funding in November 1993, was a clean-sheet race engine that happened to use pushrods. 72-degree V8 (tighter than the standard Ilmor 82-degree to raise the camshaft and shorten the pushrods). One camshaft per bank. Two valves per cylinder with pivoting cam followers and 6-to-8-inch pushrods where a normal pushrod V8 used 12-inch. Needle bearings throughout the valvetrain to eliminate friction. Twisted combustion chambers for optimal flame propagation with only two valves. Parts were flown back and forth on the Concorde between Ilmor's UK facility and Penske's Pennsylvania shop. Mario Andretti, who lived near the Nazareth test track, heard the engine running during a secret test in February 1994 and knew it wasn't a normal Indy car engine. He said nothing.
Illien promised 940 HP. The engine produced 1,024 HP at 9,800 RPM. It could rev to 10,500. The torque was so high that drivers got wheelspin exiting pit lane and hit the rev limiter on the straights. Al Unser Jr. qualified on pole at 228.011 mph. The three Penske cars with the 500I were so much faster that they lapped the field. With 16 laps remaining, Emerson Fittipaldi crashed while trying to lap his own teammate Unser. Paul Tracy retired with turbo failure. Unser won. Only rookie Jacques Villeneuve finished on the lead lap. The advantage was estimated at 150 to 200 HP over every other car in the field. Mercedes motorsport boss Norbert Haug said winning the Indy 500 was worth the investment "10 times over."
The engine was banned weeks later. USAC closed the loophole for 1995. Penske, having spent a year developing a one-race engine instead of their DOHC program, failed to qualify for the 1995 Indy 500. The 500I was used once, for one race, at one track. It won. Then it was outlawed. One engine. One race. One win. "The Beast." The greatest single-use racing engine in history.