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An Indyfied variant of Cosworth's DFV (Double Four-Valve) F1 mill, the DFX was the motor that finally ended decades of Offenhauser dominance at the Brickyard. Ken Duckworth had been a gearbox engineer at Lotus, but had left to found Cosworth with Mike Costin when he was approached by Colin Chapman with the idea for a small-displacement V8 that would act as a stressed chassis member. The DFV was such a success in the hands of drivers like Graham Hill and Jim Clark that an Indy mill was a natural outgrowth of the program.

From 1978 until 1987, the 2.4L turbo motor owned Indianapolis, responding to the right foot of hairy-chested greats like Gordon Johncock, the Unsers, Rahal, Johny Rutherford and of course, the great Rick Mears. Installed in Lolas, Penskes, Chaparrals, Marches and Wildcats, the DFX was simply the motor of an era. We grew up watching the DFX, just like our dad grew up watching the Offy. As a kid, it owned us like Gene Simmons owns Shannon Tweed.

Cosworth DFV [Wikipedia]

Cosworth's 20,000RPM V8 [Internal]