GM Quad-4 engine

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The Quad 4 (called Twin Cam after 1995) was a DOHC and SOHC straight-4 automobile engine produced by General Motors' Oldsmobile division. It was a modern engine for the time, but was criticized for roughness as well as its longevity[citation needed]. Balance shafts were added in 1995, also known as a transitional year from the Quad 4 to the renamed TWIN CAM variant, in 1996 2.4L (LD9) the complete engine makeover was accomplished. The name is derived from the engine's four cylinders and four valve per cylinder layout. There was a single overhead camshaft variant that was produced for a brief time. The Quad 4 used an iron block and an aluminum head.

The Quad 4 debuted in 1987 and was replaced after 2001 by the Ecotec. Quad 4 engines were produced at GM's Delta Engine Plant (Plant 5) in Delta Township, Michigan. In recent years, it has gained a minor following in hot rodding circles as a period style engine (which looks like a 1930's Offenhauser twin cam unit)[citation needed].

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[edit] Quad OHC

A SOHC variant of the Quad 4 was intended to replace the Tech IV. Debuting in 1992, this Quad OHC was an 8-valve engine and produced 120 hp (89 kW), 40 hp (30 kW) less than a Quad 4 from the same era. Torque was 140 ft·lbf (190 N·m).

Although power and economy were better than the pushrod Tech IV, the Quad OHC was retired after 1994 when the DOHC version became standard.

[edit] LD2

The LD2 was the standard version of the Quad 4. The LD2 was the first incarnation of the Quad 4. It is a lower output version of the Quad 4 when compared to the LGO or High Output Quad 4. There was a transitional version of the LD2 in 1995.

[edit] 1995

For 1995, a balance shaft-equipped version of the 2.3 L version was produced. A clever arrangement ensured a constant load on the shafts: The crank drove one shaft, which drives the second, which drives the oil pump. The shafts spun at twice the engine rpm, forcing the redline to be reduced from 6800 to 6500 rpm. Output was 150 hp (110 kW) and 150 ft·lbf (200 N·m). This was the only Quad 4 family engine produced in 1995. This was known as a transitional year for the engine family.

Applications:

[edit] LG0

The High-Output 2.3 L LG0 version produced 180 hp (134 kW) from 1990 to 1992, and 175 hp (130 kW) in 1993 and 1994. Changes included a higher volume intake manifold, and more aggressive camshafts.

Applications:

[edit] W41

The W41 version was the highest-output Quad 4 at 190 hp (142 kW) in 1991 and 1992, and 185 hp (138 kW) in 1993. The additional 10 hp (7.5 kW) came from longer duration cams and a different PROM.

Applications:

[edit] LD9

The LD9 Twin Cam was a 2.4 L Quad 4 variant with balance shafts, debuting in 1996. Bore was decreased from 92 mm (3.6 in) to 90 mm (3.5 in) and stroke increased from 85 mm (3.3 in) to 94 mm for better torque, and power was increased to 150 hp (112 kW). This engine received a minor update halfway through the 1999 model year that eliminated the EGR, increased the compression ratio from 9.5:1 to 9.7:1, and switched from low impedance fuel injectors to high impedance.

Applications:

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