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Quad 4 engine

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Oldsmobile Quad 4
Overview
ManufacturerOldsmobile division of GM
Also calledTwin Cam or Quad OHC
Production1987–2002
Layout
ConfigurationI4
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 materialCast iron
Cylinder head materialAluminum
Valvetrain
Compression ratio9.5:1, 9.7:1, 10.0:1
Combustion
TurbochargerExperimental engines only
Fuel systemSequential MPFI
Fuel typeGasoline
Oil systemWet sump
Cooling systemWater-cooled
Output
Power output150–190 bhp (112–142 kW)
Torque output160 lb⋅ft (217 N⋅m)
Chronology
SuccessorEcotec 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.

History

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The Quad 4 name is derived from the engine's four-cylinder, four valve-per-cylinder layout. Introduced with a displacement of 2.3-liters, the engine has a cast iron block and an aluminum head. 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.

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.

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.

Reception

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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 Oldsmobile announced in 1988 that a high-output "HO" Quad 4 with 180 bhp (134 kW) was forthcoming, as well as a 250 bhp (186 kW) turbocharged version similar to the pace car's engine, GM never released the turbocharged version as a production option. 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.[1][2]

Versions

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LD2

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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. GM was able to produce the latter output with a 9.5:1 compression ratio, meeting emission standards without using either a turbocharger or 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.[3][4] While some references rate this engine at 180 hp, Oldsmobile's own literature reports a number of 170 hp (130 kW).[5]

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:

1995

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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:

LG0

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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:

W41

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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:

L40

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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:

LD9

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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).[6] 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

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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[citation needed]

Applications:

Racing

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Applications: Oldsmobile Aerotech

See also

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References

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  1. ^ Bumbeck, Mike (23 March 2012). "Class of '87 — Quad 4 Edition". www.hemmings.com.
  2. ^ Storer, Jay (March 2007). "Fabricating Tapered Tubes — Cool Cones". Street Rodder. Source Interlink Media, Inc. Archived from the original on 2007-12-21. Retrieved 2024-10-23.
  3. ^ "1992 Oldsmobile Achieva Coupe SC". inventory.motorcargroup.com.
  4. ^ Lavery, Jeff (15 July 2022). "Quad 4 Equipped: 1992 Oldsmobile Achieva SC". barnfinds.com.
  5. ^ "1994 Achieva By Oldsmobile" (PDF). xr793.com. Oldsmobile.
  6. ^ "1996 Cavalier Specifications — Engine, Capacities and Transmission". media.gm.com. Archived from the original on 2004-05-11. Retrieved 2024-10-23.
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