The 265 V8
Both engineers were working at Cosworth on the Cosworth DFX turbocharged methanol engine for the CART Indy Car World Series; differences of opinion over the direction in which DFX development should go (Cosworth were inherently conservative as they had a near monopoly) led them to break away from their parent company to pursue their own ideas. There was some acrimony in their split from Cosworth, their former employer claiming that the Ilmor engine was little different to their planned modifications to the DFX.
Founded as an independent British engine manufacturer in 1983, it started building engines for Indycars with the money of team owner and chassis manufacturer Roger Penske. The Ilmor-Chevrolet 265A debuted at the 1986 Indianapolis 500 with Team Penske driver Al Unser. In 1987, the engine program expanded to all three Team Penske drivers (Rick Mears, Danny Sullivan, and Unser), Patrick Racing, and Newman/Haas Racing. Mario Andretti, driving for Newman/Haas, won the Long Beach Grand Prix, the engine's first IndyCar victory. He also won the pole position for the 1987 Indianapolis 500. A year later, the engine was rebadged as the Chevy Indy V-8, and Rick Mears won the 1988 Indianapolis 500, the engine's first win at Indy. The engine went on to have a stellar record in CART. From 1987 to 1991, the engine won 64 of 78 races.
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