Mario Illien and
Paul Morgan were working at Cosworth on the
Cosworth DFX turbocharged methanol engine for the
CART Indy Car 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 from their planned modifications to the DFX.
1986 Founded as an independent British engine manufacturer in 1983, Ilmor started building engines for
Indy cars with financial backing from team owner and chassis manufacturer
Roger Penske. The Ilmor 265-A, badged initially as the Ilmor-
Chevy Indy V8, debuted in
1986. The engine was used part-time by Penske team drivers, with
Al Unser Sr. racing it at the
1986 Indianapolis 500. Mears notched two poles and two 3rd place finishes with the engine late in the season.
1987–1991 In 1987, the 265-A engine program expanded to full time at
Penske Racing. Penske's primary drivers
Rick Mears and
Danny Sullivan raced it full-time. A third car was entered at Indianapolis for
Danny Ongais. However, Ongais was injured in a crash during practice. He was replaced by
Al Unser Sr. (who instead fielded a Cosworth). The 265-A was also fielded by
Newman/Haas Racing (
Mario Andretti) and at
Patrick Racing (
Emerson Fittipaldi and
Kevin Cogan). Andretti won at
Long Beach, the engine's first Indy car victory. He also won the pole position for the
1987 Indianapolis 500. With the 265-A engine now badged as the Chevrolet Indy V8,
Rick Mears won the
1988 Indianapolis 500, the engine's first win at Indianapolis. The engine went on to have a stellar record in
CART. From 1987 to 1991, the "Chevy-A" engine won 64 of 78 races including the Indy 500 from 1988 to 1991.
1992 In
1992, the 265-B engine was introduced. The "Chevy-B" was fielded singly by Penske Racing (
Rick Mears and
Emerson Fittipaldi) in 1992 and won four CART series races. All other Ilmor teams remained with the venerable 265-A for 1992.
Bobby Rahal, driving a "Chevy-A" won the 1992 CART championship, the fifth consecutive (and final) for the 265-A.
Al Unser Jr. won the
1992 Indianapolis 500 driving a "Chevy-A", also the fifth consecutive (and final) Indy 500 win for the 265-A.
Emerson Fittipaldi drove a "Chevy-B" to 4th place in points, but both he and Mears dropped out of that year's Indy 500 due to crashes. At this time Ilmor faced new competition from
Cosworth, which had just introduced their new
Ford-Cosworth XB V8.
1993–1994 For the
1993 season, the 265-C engine was introduced as a replacement for both the 265-A and the 265-B. The "Chevy-C" was used widely, and brought continued success for Ilmor. Some backmarker teams continued to run 265-A or 265-B engines during the 1993 season, but neither the "A" nor the "B" would win another Indy car race. Chevrolet dropped its badging support after the 1993 season. In 1994, Ilmor introduced two new engines, the
265-D and the
265-E. The "D" would later be badged as the "Ilmor
Mercedes-Benz D". The "E" was a top-secret purpose-built, V8
pushrod engine developed for
Team Penske for the
1994 Indianapolis 500. While most Ilmor teams upgraded to the "D", the "C" and a variant called the "C+" saw some limited use during the 1994 season. ==Applications==