Quad 4 engine

Quad 4 is the name of a family of straight-four engines produced by General Motors' Oldsmobile division. Several double overhead camshaft (DOHC) versions were produced between 1987 and 2002, and one single overhead camshaft (SOHC) model was built from 1992 to 1994.

Oldsmobile Quad 4
Overview
Manufacturer	Oldsmobile division of GM
Also called	Twin Cam or Quad OHC
Production	1987–2002
Layout
Configuration	I4
Displacement	2,260 cc (137.9 cu in) 2,392 cc (146.0 cu in)
Cylinder bore	92 mm (3.62 in) 90 mm (3.54 in)
Piston stroke	85 mm (3.35 in) 94 mm (3.7 in)
Cylinder block material	Cast iron
Cylinder head material	Aluminum
Valvetrain	DOHC 4 valves per cyl. SOHC, 2 valves per cyl.
Compression ratio	9.5:1, 9.7:1, 10.0:1
Combustion
Turbocharger	Experimental engines only
Fuel system	Sequential MPFI
Fuel type	Gasoline
Oil system	Wet sump
Cooling system	Water-cooled
Output
Power output	150–190 bhp (112–142 kW)
Torque output	160 lb⋅ft (217 N⋅m)
Chronology
Successor	Ecotec engine

History

The Quad 4 is the first wholly domestic regular production DOHC four-cylinder engine 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 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.

Although Oldsmobile announced in 1988 that a both high-output "HO" Quad 4 with 180 bhp (134 kW), and a 250 bhp (186 kW) turbocharged version similar to the pace car's engine were forthcoming, a turbocharged version was never released as a production option.

All Quad 4 family engines 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 were based on the Cadillac Northstar V8 architecture.

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.

Common features

The Quad 4 name is derived from the engine's four-cylinder, four valve-per-cylinder layout. The engine has a cast iron block. The head, camshaft carriers, and timing chain cover are aluminum, and the sump is die-cast aluminum.

Although cogged timing belts were becoming popular among contemporary overhead cam designs, the Quad 4 uses timing chains to drive both camshafts, as well as the water pump.

Fuel is delivered by an electronic fuel injection system, and spark is produced by a distributorless ignition system called "direct-fire", that alternately fires two ignition coils located under the cast aluminum engine cover.

Reception

Following the engine's release in 1988, Oldsmobile promoted the Quad 4 name at highly publicized events with cars like the Oldsmobile Aerotech. At the 1988 Indianapolis 500, the pace car was an Oldsmobile Cutlass Supreme convertible powered by a turbocharged Quad 4. Although the purpose-built engine in the Oldsmobile Aerotech was turbocharged, it was solely meant to showcase the engine's capability.

After positive reviews for the first few years of sales, the automotive press began to criticize the Quad 4 for its noise, vibration, and harshness (NVH) levels when compared to turbocharged four-cylinders, V6s, and occasionally V8s. The Quad 4 underwent two rounds of exhaust port size reductions, followed by the addition of balance shafts in 1995 to address its NVH. Further changes were made for the 1996 model year when the engine's bore and stroke were changed, and the engine was subsequently renamed as the "Twin Cam".

The design gained a minor following in hot rodding circles because it looked similar to a 1930s Offenhauser engine once the ribbed aluminum cover was removed, exposing the tall "cam towers" and the deep valley between them holding the spark plugs.

Versions

LD2

A 2.3-liter Quad 4 in 1989 Cutlass Calais

The LD2 is the original version of the Quad 4, introduced in 1987 for the 1988 model year. Bore × stroke are 92 mm × 85 mm (3.6 in × 3.3 in), for a displacement of 2,260 cc (137.9 cu in). In base form it put out 150 bhp (112 kW) from 1988 to 1989 and 160 bhp (119 kW) from 1990 to 1992. The naturally aspirated Quad 4 was able to produce that power with a 9.5:1 compression ratio, was able to meet emission standards without using an EGR system.

Minor running changes to the base Quad 4 included different crankshafts, cams, and manifolds, all meant to increase torque and reduce NVH.

A slightly augmented version of the LD2 was offered in some Oldsmobile Achieva models with the SC (and possibley SL) trim packages. In this application the LD2 engine had a device called a vortex valve installed in the throttle body, and a ram-air cold-air intake was installed near the driver's side headlamp with ducting to direct the air to the engine intake. While some references rate this engine at 180 hp, Oldsmobile's own literature reports a number of 170 hp (130 kW).

There was also a transitional version of the LD2 in 1995, with the same displacement as the early Quad 4 but having the dual balance shafts of the later 2.4-liter LD9 Twin Cam.

Applications:

• 1988–1991 Buick Skylark
• 1992–1994 Oldsmobile Achieva
• 1988–1991 Oldsmobile Cutlass Calais
• 1990–1991 Oldsmobile Cutlass Supreme
• 1988–1994 Pontiac Grand Am
• 1990–1991 Pontiac Grand Prix
• 1993–1997 Pontiac Trans Sport (Europe only)

1995

A 2.3-liter Quad 4 in 1995 Chevrolet Cavalier Z24

For 1995 only, a balance shaft-equipped version of the 2.3-liter version was produced. This arrangement ensures a constant load on the shafts: the crank drives one shaft, which drives the second, which then drives the oil pump. The shafts spin at twice the engine rpm, forcing the redline to be reduced from 6800 to 6500 rpm. Output is 150 bhp (112 kW) and 150 lb⋅ft (203 N⋅m). This was the only Quad 4 produced in 1995, and was known as a transitional year for the engine family.

Applications:

• 1995 Pontiac Sunfire GT
• 1995 Chevrolet Cavalier Z24
• 1995 Pontiac Grand Am
• 1995 Oldsmobile Achieva
• 1995 Buick Skylark

LG0

The "high output" 2.3-liter LG0 was rated at 180 hp (134 kW) from 1989 to 1992, 175 hp (130 kW) in 1993 and 170 hp (127 kW) in 1994. Both the 1993 and 1994 power reductions were a direct result of the first two rounds of exhaust port size reductions for NVH control. The LG0 is differentiated from the LD2 engine by aggressive camshafts and an extra half point of compression; 9.5:1 to 10.0:1. Premium fuel with a 91 octane rating or higher was recommended for these engines due to the compression ratio.

The LG0 was introduced with special production runs of 200 Cutlass Calais International Series coupes, and 200 Grand Am SE coupes, all featuring bright red paint and gray interiors. It was only available when paired with the heavy-duty Getrag-designed HM-282/NVG-T550 five-speed manual transmission.

A limited production version of the LG0 engine was offered in select Oldsmobiles with the designation "W41" (listed below).

LG0 applications:

• 1990–1993 Chevrolet Beretta GTZ
• 1994 Chevrolet Beretta Z26
• 1989–1991 Pontiac Grand Am SE
• 1990–1991 Pontiac Grand Am LE with the "sport performance package" (RPO: W32)
• 1992–1994 Pontiac Grand Am GT
• 1989–1991 Oldsmobile Cutlass Calais International Series
• 1990–1991 Oldsmobile Cutlass Calais Quad 442
• 1992–1994 Oldsmobile Achieva SC
• 1990 Oldsmobile Cutlass Supreme International Series

W41

A 2.3-liter Quad 4 W41 engine

The W41 was the most powerful Quad 4. The 1991–1992 W41s were rated at 190 hp (142 kW), while the 1993 W41 was rated at 185 hp (138 kW) as a result of the first round of exhaust port size reduction to improve emissions and other changes to the Quad 4 architecture to reduce NVH. The additional 10 hp (7 kW) came from longer duration cams and a different PROM.

Part of the W41 drivetrain was a specific version of the HM-282/NVG-T550 with a gear set otherwise unavailable. All W41 five-speed transmissions had a final drive ratio (FDR) of 3.94:1 whereas the 1988–1992½ LD2 and LG0 transmissions all used a 3.61:1 FDR; the 3.94:1 FDR was used on all 1992½–1994 LG0 transmissions, but retained the standard HM-282/NVG-T550 gear set.

W41 applications:

• 1991 Oldsmobile Cutlass Calais
• 1992–1993 Oldsmobile Achieva SCX

L40

Quad OHC engine

This SOHC variant of the Quad 4 was intended to replace the Pontiac 2.5 L Tech IV OHV "Iron Duke" engine. Debuting in 1992 and called the Quad OHC, this eight-valve engine produced 120 hp (89 kW), 40 hp (30 kW) less than the Quad 4s of the same era. Torque was 140 lb⋅ft (190 N⋅m). Power dropped to 115 hp (86 kW) in 1993 with an attempt by GM to reduce the NVH of the engine.

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

Applications:

• 1992–1994 Oldsmobile Achieva
• 1992–1994 Pontiac Grand Am
• 1992–1994 Buick Skylark

LD9

A 2.4-liter Twin Cam in 1997 Pontiac Sunfire

The LD9 Twin Cam was a 2.4-liter Quad 4 variant which debuted in 1996 with balance shafts and a redesigned cylinder head. In the mid-1990s, these engines, like their earlier 2.3-liter counterparts, were known for timing chain failures, as well as water pump failures, in which the water pumps were often difficult and costly to access and replace. LD9s also had very small oil passages, making for less than adequate lubrication, and costly engine repairs if not maintained properly. Bore was decreased from 92 to 90 mm (3.62 to 3.54 in) and stroke increased from 85 to 94 mm (3.35 to 3.70 in) for better torque. Power came in at 150 bhp (112 kW). This engine received a minor update halfway through the 1999 model year that eliminated the exhaust gas recirculation, increased the compression ratio from 9.5:1 to 9.7:1, and switched from low impedance fuel injectors to high impedance. For increased reliability this engine also saw other minor updates in the 2000s towards the end of its use in General Motors vehicles. In 2001, changes included a smaller knock sensor, flat-top pistons instead of dished, new oiling passages, newer stronger timing chain, a redesigned water pump, a redesigned starter motor, and a higher capacity catalytic converter. An improved belt-tensioner was introduced in 2002.

Specifications post-1999

Engine type	Inline 4-cylinder DOHC 16v
Displacement	146 cu in (2.4 L)
Bore	90 mm (3.54 in)
Stroke	94 mm (3.70 in)
Compression ratio	9.7:1
Fuel delivery	Sequential fuel injection (SFI)
Peak power	150 hp (112 kW) at 5600 rpm
Peak torque	155 lb⋅ft (210 N⋅m) at 4400 rpm
Estimated fuel mileage	23 mpg‑US (10 L/100 km; 28 mpg‑imp) city / 33 mpg‑US (7.1 L/100 km; 40 mpg‑imp) highway

Applications:

• 1996–2002 Chevrolet Cavalier Z24
• 1996–2002 Pontiac Sunfire GT
• 1996–2001 Pontiac Grand Am
• 1996–1998 Oldsmobile Achieva
• 1999–2001 Oldsmobile Alero
• 1997–2000 Chevrolet Malibu
• 1996–1998 Buick Skylark

Racing

• 
  Early experimental racing engine
• 
  900 hp (671 kW) — rear. Single turbocharger.
• 
  900 hp (671 kW) — side
• 
  1,000 hp (746 kW) Twin-turbochargers.

Applications: Oldsmobile Aerotech

See also

• List of GM engines

External links

• "Quad4forums.com". 2005-04-30. Archived from the original on 2008-05-30. Retrieved 2024-10-23.
• "Yahoo group QuadForum mailing list". Archived from the original on 2013-01-05. Retrieved 2024-10-23.