Editing Quad 4 engine (section)

==History==
The Quad&nbsp;4 is the first domestic regular production DOHC four-cylinder engine wholly designed and built by GM, the only similar prior example being the [[Chevrolet Cosworth Vega]], whose DOHC head was designed by [[Cosworth]] in England. In addition to the 2.3-liter DOHC Quad&nbsp;4s, there was also a short-lived 2.3-liter SOHC variant called the "Quad OHC", available from 1992 to 1994, and the 2.4-liter Twin Cam, available from 1996 to 2002.

The Quad&nbsp;4 was originally expected to debut in 1987, but was delayed for one year. From as early as 1988, Oldsmobile announced that a high-output "HO" Quad&nbsp;4 with {{cvt|180|bhp|kW|0}} was forthcoming.<ref name="jalopnik-mar2019"/>

All Quad&nbsp;4 family engines were produced at the [[Lansing Engine Plant]] (plant five) in [[Delta Charter Township, Michigan|Delta Township]] near [[Lansing, Michigan]]. The Twin Cam was the last engine that was engineered and produced solely by Oldsmobile; the [[Oldsmobile Aurora engine|Aurora V8]] and [[Northstar engine series#LX5 (Shortstar)|Shortstar V6]] were based on the [[Cadillac]] [[Northstar engine series|Northstar V8]] architecture.

First released to the public as a regular production option for the 1988 [[Oldsmobile Cutlass Calais]] and [[Pontiac Grand Am#1985–1991|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.

The Quad&nbsp;4 underwent two rounds of [[Cylinder head porting|exhaust port size reductions]], followed by the addition of [[balance shafts]] in 1995 to address its levels of [[noise, vibration, and harshness]] (NVH). Further changes were made for the 1996 model year when the engine's [[Bore (engine)|bore]] and [[Stroke (engine)|stroke]] were changed, and the engine was subsequently renamed the "Twin Cam".

The Quad&nbsp;4 engine lineup was cancelled after the 2002 [[model year]]. It was replaced by the [[GM Ecotec engine|Ecotec]] for the 2003 model year.