Quad 4 is the name of a family of principally DOHC inline four-cylinder engines produced by General Motors' Oldsmobile division between 1987 and 2002; a single SOHC version was built between 1992 and 1994. Its name was derived from the engine's four-valve, four-cylinder layout. Introduced with a displacement of , the engine was a modern design for its time, using a cast-iron block and an aluminum head. Even though belts were more popular for this purpose on OHC engines at the time, chains were used to time the camshafts to the crankshaft. The water pump is also driven by the timing chain. The Quad 4 was the first wholly domestic regular production DOHC four-cylinder engine designed and built by GM; the only prior DOHC four-cylinder engine offered by GM was the Cosworth Vega, which featured a DOHC head designed by Cosworth in England. In addition to the DOHC versions, there was also both a short-lived SOHC variant, the "Quad OHC", available from 1992 to 1994, and the Twin Cam from 1996 to 2002. All engines in the Quad 4 family were produced at the Lansing Engine Plant (plant five) in Delta Township near Lansing, Michigan. The Twin Cam was the last engine that was engineered and produced solely by Oldsmobile; the Aurora V8 and Shortstar V6 shared architecture with the Cadillac Northstar V8. First released to the public as a regular production option for the 1988 Oldsmobile Cutlass Calais and Pontiac Grand Am, the engine's availability expanded to Buick in late 1988 and Chevrolet in 1990, after which it became a mainstay in GM's lineup until its cancellation after the 2002 model year. It was replaced by the Ecotec for the 2003 model year. Reception Simultaneous to the engine's release in 1988, Oldsmobile attempted to further the Quad 4 name through highly publicized events featuring such cars as the Oldsmobile Aerotech. Another such event was the 1988 Indianapolis 500, when Oldsmobile was chosen to pace the race with a convertible version of their Cutlass Supreme, and a pre-production turbocharged Quad 4 was the engine of choice for their pace car. Although it was publicized in 1988 that the Quad 4 was forthcoming in a "HO", as well as a turbocharged version (the same engine that was in the pace car that year), GM never released the turbocharged version as a publicly available option. Although the engine in Oldsmobile Aerotech was