GM Quad-4 Engine

GM Quad-4 Engine

The engine family known as the Quad 4 was debuted to the public in the spring of 1987. The Quad 4 was a 2,260.5 cc (2.2605 L; 137.94 cu in) DOHC inline 4-cylinder produced by General Motors' Oldsmobile division. Early television ads touting the new engine's abilities showed video of a limited edition Oldsmobile Calais (called the "GMO Quad-4") racing around city streets.

The Quad 4 name is derived from the engine's four-valve, four-cylinder layout. 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, which were useful because of the interference design of the engine. 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.

First released to the public as 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.

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 Indy 500 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 180 bhp (130 kW) "HO", as well as a 250 bhp (190 kW) turbocharged version (the same engine that was in the pace car that year), GM never released the turbocharged version as an option. Also, the engine in Oldsmobile Aerotech was a purpose-built, turbocharged example; it was solely meant to showcase the capability of the engine's design.

After the first couple years of rave reviews of the Quad 4, the automotive press began to criticize it for its NVH. At the time, the Quad 4 was generally compared to, or against turbocharged four cylinders, V6's, and occasionally V8's. The first changes of the Quad 4 to address NVH were two rounds of exhaust port size reductions, followed by the addition of balance shafts in 1995. Further changes were made for the 1996 model year when the engine's bore & stroke were changed, and the engine was subsequently redubbed Twin Cam.

In addition to the 2,260.5 cc (2.2605 L; 137.94 cu in) DOHC versions, there were also both a short-lived SOHC variant, Quad OHC, available from 1992 to 1994, and the 2,392.3 cc (2.3923 L; 145.99 cu in) Twin Cam from 1996 to 2002. The Twin Cam was replaced by the Ecotec for the 2003 model year.

All engines in the Quad 4 family were produced at the Lansing Engine Plant (plant 5) 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 Intrigue V6 shared architecture with the Cadillac Northstar.

In recent years, the design has gained a minor following in Hot Rodding circles as a period style engine because it looks similar to a 1930s Offenhauser DOHC design.