Buick V6 engine

The 3800's block is cast iron and all variants use iron, two-valve-per-cylinder OHV heads. The engine, originally designed and manufactured in the United States, was also produced in later versions in Australia. It was the first six-cylinder engine designed exclusively for Buick products since the Buick straight-six was discontinued in 1930.

In 1967, GM sold the design to Kaiser-Jeep since they no longer felt the need to produce a V6, considered an unusual engine configuration in North America at the time. The 1973 oil crisis prompted the company to re-acquire the design from American Motors (AMC), who had purchased Kaiser-Jeep in 1970, in early 1974. The descendants of the early 231 continue as the most-common GM V6, as it developed into a very durable and reliable design.

Though the pre-3800 rear-wheel drive (RWD) V6 uses the Buick, Oldsmobile, Pontiac (BOP) bellhousing pattern, an oddity of both the front-wheel drive (FWD) and RWD 3800 V6 is that although it is a 90° V6, it uses the GM 60° V6 bell housing (Metric Pattern). For use in the FWD applications, the bellhousings on the FWD transmissions are altered slightly.

This engine has the cylinders numbered 1-3-5 on the left-hand bank (front bank for FWD applications) and 2-4-6 on the right-hand bank, the number 1 cylinder being the furthest from the flywheel end. The firing order is 1-6-5-4-3-2.

The engine was produced at the Flint North plant in Flint, Michigan, with engine blocks and cylinder heads cast at the Grey Iron plant (now the GM Saginaw Metal Casting Operations plant) at 1629 N. Washington Avenue in Saginaw, Michigan.

The first engine in this family, RPO code 6I, was introduced in 1961 for the 1962 model year Buick Special with Buick's 198 cu in (3.2 L) engine, the first V6 in an American car (the GMC V6 was used earlier in trucks). Because it was derived from Buick's 215 cu in (3.5 L) aluminum V8, it has a 90° bank between cylinders and an uneven firing pattern due to the crankshaft having only three crank pins set at 120° apart, with opposing cylinders (1-2, 3-4, and 5-6) sharing a crank pin in, as do many V8 engines. The uneven firing pattern was often perceived as roughness, leading a former American Motors executive to describe it as "rougher than a cob."

The off-center design continued up until the 1988 LN3 version of the engine, when the left-hand bank of cylinders was moved forward relative to the right-hand bank. Although the actual bore spacing between cylinders on the same bank remained unchanged at 4.24 in (108 mm), the LN3 and later engines became known to have "on-center bore spacing".

The Buick Division, concerned about high manufacturing costs of their innovative aluminum 215 V8, sought to develop a cheaper, cast-iron engine based on the same tooling. It was given the RPO code JL. They settled on an unusual 90° V6 layout that was essentially the architecture of the '215' less two cylinders. In initial form, it had a bore and stroke of 3.625 in × 3.1875 in (92.08 mm × 80.96 mm), for an overall displacement of 198 cu in (3.2 L). It weighed about 35 lb (16 kg) more than the aluminum engine, but was far cheaper to produce. Dubbed the Fireball V6, it became the standard engine in the 1962 Buick Special. In their test that year, Road & Track was impressed with Buick's "practical" new V6, saying it "sounds and performs exactly like the aluminum V8 in most respects."

The bore was increased to 3.75 in (95.25 mm), and stroke increased to 3.4 in (86.4 mm), increasing displacement to 225 cu in (3.7 L). Since the engine was similar to the popular small-block Buick V8—now with a cast-iron block and displacement of 300 cu in (4.9 L), the engine was made cheaply at the same factory with much of the same tooling. This engine carried the RPO code KH for the 1964 model year and LH for 1965. In 1966, the code was MH and was renamed the Wildcat V-6. For 1967, the code was NH. This engine was used in Buick's intermediate-sized Special and Skylark models from 1964 to 1967 and Oldsmobile's mid-sized F-85/Cutlass models for 1964 and 1965, including the Oldsmobile Vista Cruiser and Buick Sport Wagon.

1964–1965 models featured a single barrel Rochester MonoJet, producing 155 hp (116 kW). In 1966–1967, the 1-barrel was replaced with a 2-barrel Rochester 2GV, giving the engine a 5-horsepower boost to 160 hp (119 kW).

The V6 was dropped after the 1967 model year in favor of a conventional 250 cu in (4.1 L) inline-six engine built by the Chevrolet division, and the tooling was sold to Kaiser-Jeep.

In 1965, Kaiser-Jeep began using the Buick 225 in Jeep CJs. It was known as the Dauntless V6 and used a much heavier flywheel than the Buick version to damp vibrations resulting from the engine's firing pattern. Buick sold the tooling for this engine to Kaiser in 1967, as the demand for the engine was waning steadily in an era of V8s and muscle cars. When American Motors (AMC) bought Jeep, the V6 was replaced with AMC straight-6 engines, but the ownership of the V6 tooling remained with AMC.

The 1973 oil crisis prompted GM to look for more economical engines than the V8s of 350, 400, and 454/455 cubic inches that powered most General Motors cars and trucks during that time. At that time, the only "small" engines generally offered by GM were built by the Chevrolet division including the 140 cu in (2.3 L) OHC aluminum inline-four engine used in the subcompact Chevrolet Vega and a 250 cu in (4.1 L) straight-6 used in smaller Chevy, Buick, Oldsmobile and Pontiac models, whose design roots dated back to the 1962 Chevy II (Nova). LD5 was the RPO for engines with chassis code "A", LD7 was used for the 1977-only VIN code "C" engines.

One quick idea was tried by Buick engineers—taking an old Fireball V6 picked up at a junkyard and installing it into a 1974 Buick Apollo. The solution worked so well that GM wanted AMC to put the engine back into production. However, AMC's cost per unit was deemed as too high. Instead of buying completed engines, GM made an offer to buy back the tooling and manufacturing line from AMC in April 1974, and began building the engines on August 12.^[1] With production back within GM, Buick re-introduced the V6 that fall in certain 1975 models—a move made possible by the fact that foundations for the old V6 machinery were still intact at Buick's engine assembly plant in Flint, Michigan, so it was easy to put the old tooling back in place and begin production at least two years ahead of the normal schedule that would have been required to create new tooling. The bore was enlarged to 3.8 in (97 mm), identical to the Buick 350 and Olds 307 V8s, yielding 231 cu in (3.8 L) displacement. 78,349 units were installed in Buicks for 1975.^[2]

Due to difficulties with the new fuel economy and emissions standards, the engine produced just 105 or 110 hp (78 or 82 kW), depending on fitment and year.

In 1977, Buick redesigned the crankshaft to a "split-pin" configuration to create an "even-firing" version. The crank pins associated with the opposing cylinders were offset from each other by 30°. The relatively small offset did not require flying arms to be incorporated, however a 3 mm (0.12 in) thick flange was built in between the offset crank pins to prevent the connecting rod big-ends from "walking" off the crank pin bearing journal and interfering with the adjacent big end. The 3 mm (0.12 in) thick flange effectively caused the connecting rods on the left-hand bank of cylinders (forward bank for FWD applications) to move 1.5 mm (0.059 in) forward and the right-hand bank to move 1.5 mm (0.059 in) rearward, but the engine block remained unchanged compared to the odd-fire engine. Since the cylinders center-lines were no longer centralized over the crank pin bearing journals, the connecting rods were re-designed with the big-ends offset from the piston pin ends by 1.5 mm (0.059 in). The engine in this configuration became known to have "off-center bore spacing".

 

In 1978, GM began to market the 231 as the 3.8 liter as metric engine sizes became common in the United States. The RPO Code was LD5, though California-emissions versions were called LC6. Starting in 1979, the engine was used in the front-wheel drive Buick Riviera, though still with a longitudinal mounting. Larger valves and better intake and exhaust boosted the power output for 1979.

A turbocharged version was introduced as the pace car at the 1976 Indianapolis 500, and a production turbo arrived in 1978. The turbo 3.8 received sequential fuel injection and a wasted spark Distributorless Ignition System in 1984. In 1986, an air-to-air Garrett intercooler was added and the RPO Code became LC2. The LC2 engine has a bore and stroke of 3.8 in × 3.4 in (96.5 mm × 86.4 mm). The horsepower ratings for 1986 & 1987 were 235 and 245 hp (238 and 248 PS; 175 and 183 kW), respectively. The limited production GNX benefitted from additional factory modifications such as a ceramic turbocharger, more efficient Garrett intercooler, low restriction exhaust system and revised programming which resulted in a 300 hp (304 PS; 224 kW) factory rating.

The turbocharged 1987 Buick Regal Grand National GNX was called America's quickest automobile, and the model continues to be collected and appreciated today.

A smaller version of this engine was produced in 1978 and 1979 for the Century, Regal, and Chevrolet Monza. The bore was reduced to 3.5 in (88.9 mm), resulting in an engine of 196 cu in (3.2 L) piston displacement. The RPO code was LC9. Initially this engine produced 90 hp (67 kW), but in 1979 it received the same improvements in the cylinder heads as did the LD5, and therefore power increased to 105 hp (78 kW).

In response to rising gas prices, a larger 252 cu in (4.1 L) version of the 3.8 liter LD5 V6 was produced from 1980 through 1984 and marketed as an alternative to a V8. The bore was enlarged to 3.965 in (100.7 mm), yielding an output of 125 hp (93 kW) and 205 lb⋅ft (278 N⋅m). This engine was used in many large rear-wheel drive Buicks, and in some models from each of GM's other divisions, including Cadillac which offered the "big" Buick V6 in several models from 1980 to 1982 as a credit option to the troublesome V8-6-4 engine used in 1981 and early versions of the aluminum-block Cadillac HT-4100 V8 introduced in 1982. It was also the standard powerplant in the front-drive Riviera and Oldsmobile Toronado from 1981 to 1984. Additionally, the 4.1 block was used unsuccessfully at Indianapolis for racing. Its only weakness was the intake valve seals. This was the first naturally aspirated GM V-6 to feature a 4-barrel carburetor.

A small 181 cu in (3.0 L) version of the Buick V6 was produced for GM's 1980s front-wheel drive cars. Introduced in 1982, it was a lower deck version of the 3.8 designed for transverse application in the new GM A platform cars such as the Buick Century and Oldsmobile Cutlass Ciera. It shared the same bore size as its larger sibling, but featured a smaller stroke of 2.66 in (68 mm). It used a Rochester E2ME 2-bbl carburetor and the VIN code for the engine is E.

The LN7 is a multiport fuel injected version of the LK9. It was introduced for 1985 and used the VIN code: L. It was replaced in 1989 with the 3.3.

In mid-1984, the 3.8 liter LD5 engine was modified for transverse-mounting in smaller, FWD vehicles, and equipped with multi point fuel injection (MPFI). 1984-1985 models used a distributor and a distributorless wasted spark ignition system was added for all engines produced in 1986 and later. In 1986, it received sequential fuel injection (SFI) and it was initially produced in two forms, the LG2 with flat lifters (tappets), and the LG3 with a roller camshaft and lifters. The latter was offered in various models through 1988. From 1986, the 3.8 had a revised, crankshaft-driven oil pump which eliminated a longstanding problem with pump housing wear and loss of prime. Power produced by this engine was:

• VIN code B (LG2): flat lifters (tappets)
  • 140 hp (104 kW) at 4,400 rpm, 200 lb⋅ft (271 N⋅m) at 2,000 rpm
• VIN code 3 (LG3): roller lifters (tappets)
  • 125 hp (93 kW) at 4,400 rpm, 195 lb⋅ft (264 N⋅m) at 2,000 rpm (1984–1985 MPFI)
  • 150 hp (112 kW) at 4,400 rpm, 200 lb⋅ft (271 N⋅m) at 2,200 rpm (1986–1988 SFI)

 

Introduced in 1988 and initially designated VIN code C, the 3800 LN3 would later be loosely considered the Pre-Series I, although the older 3.8 SFI (LG3) was still available that year in some models. The LN3 was a major redesign, with a change to on-center bore spacing (created by moving the left-hand bank of cylinders forward relative to the right-hand bank)^[3] and the addition of a balance shaft. Other features included a 3×/18× crank-trigger system and multiport fuel injection. This generation continued in use in several GM products into the early 1990s. It produced 165 hp (123 kW) of power and 210 lb⋅ft (285 N⋅m) of torque.

The LN3 is very closely related to the Series I L27 and Series I L67 Supercharged. In fact, supercharger-related hardware can be fitted to an LN3 without changing the cylinder heads. However, the ECM would have to be reprogrammed. The L27 has a two piece, upper plenum intake and lower intake, the LN3 is all one piece.

 

A smaller 3.3 liter 3300 was introduced in 1989 and produced through 1993. It was effectively a lower-deck version of the 3800, with a smaller bore and stroke of 3.7 in × 3.16 in (94.0 mm × 80.3 mm) for 3,340 cc (3.3 L; 203.8 cu in).^[4] Like the 3800, it used a cast iron block and heads, push rods, and hydraulic lifters. Unlike the 3800, however, it used a batch-fire injection system rather than sequential injection, as evidenced by the lack of a cam position sensor. It also did not have a balance shaft. Power output was 160 hp (119 kW) at 5,200 rpm and 185 lb⋅ft (251 N⋅m) at 2,000 rpm with a 5,500 rpm redline.

 

The LN3 was replaced by the 3,791 cc (3.8 L; 231.3 cu in) L27 in mid-1990 and produces 170 hp (127 kW). The slight power increase was accompanied by more torque in the mid-range, all thanks to a new, two-piece intake manifold with longer runners. Other improvements over the LN3 included wider connecting rod bearings, a new timing chain tensioner, dual-wall exhaust pipes, new heat shields for the exhaust manifolds, and sound absorbing, composite molded valve covers.^[5] This engine is referred to as the Series I 3800, or 3800 TPI (Tuned Port Injection).

In Australia, the LN3 was also replaced by the L27 by Holden who used the engine in their series 2 (1991) VN Commodore range. However, the Australian L27 retained the LN3's one piece upper intake and lower plenum. Power was still boosted to 127 kW (170 hp) for the Holden L27, before being boosted to 130 kW (177 PS; 174 hp) in the revised VR Commodore in 1993. The L36 made its debut in 1995.

 

The Series I Supercharged engine went through two supercharger revisions (Gen2 and Gen3) and the horsepower improved between initial launch and the time that the Series II L36 was introduced. The M62 supercharger was manufactured by Eaton, for the GM 3800 SI engine. HP was rated at 205 for 1991–1993 engines (Gen2 supercharger) with a 2.55-inch (65 mm) pulley, and 225 for 1994–1995 engines (Gen3 supercharger). All of the additional horsepower for 1994–95 Gen3 supercharged engines was gained by using epoxy (not Teflon as commonly believed) coated supercharger rotors to improve efficiency, a larger supercharger inlet and throttle body. Thus, the Gen3 utilized a 2.85-inch (72 mm) pulley versus the 2.55-inch (65 mm) pulley on the Gen2. The easiest way to spot the difference between the Gen2 and Gen3 is the smaller pulley and the ribs on the side of the Gen2 extend all the way down the sides, while the Gen3 ribs are on only the top. They perform slightly differently, and interchanging one without tuning may cause engine problems. Redline on Gen3 engines is at 6000 rpm, but the ECM will shift at 5400 rpm without performance shift enabled.

Introduced in 1995, the Series II is quite a different engine. It is also by far the most popular of the 3800 family for its power, smoothness, fuel efficiency, and reliability, although the stroke for the 3.8 liter engine remained at 3.4 in (86 mm), and the bore remained at 3.8 in (97 mm). That said, the engine architecture was vastly changed. The deck height is shorter than the Series I, reducing weight and total engine package size. This required that the piston connecting rods be shortened 1 in (25.4 mm), and the crankshaft was also redesigned. A new intake manifold improved breathing while a redesigned cylinder head featured larger valves and a higher compression ratio. The result was 205 hp (153 kW) and 230 lb⋅ft (312 N⋅m), better fuel economy, and 26 lb (12 kg) lighter overall weight (to 392 lb (178 kg)). This 3800 weighs only 22 lb (10 kg) more than the all-aluminum High Feature V6 that currently dominates GM's six-cylinder applications, despite being an all cast-iron design.

The new intake manifold greatly improved airflow. To meet emissions standards, an EGR tube was placed in the intake manifold to reduce combustion temperatures.

The 3800 Series II was on the Ward's 10 Best Engines list for 1995 through 1997.

GM recalled 1.5 million vehicles with this engine on April 14, 2009 due to risk of fire from engine oil leaking under the valve cover gaskets onto hot exhaust manifolds. The fire could spread to the nearby plastic spark plug wire retainers on the valve cover and then to the rest of the engine compartment. GM fitted the affected vehicles with redesigned spark plug wire retainers.^[6] These engines were noted for having problems with the plastic upper intake manifold cracking around the EGR passage. The engine would then hydrolock. The lower intake gaskets and upper intake manifolds were revised, correcting all these issues.

 

 

 

The L67 is the supercharged version of the 3800 Series II L36 and appeared in 1996, one year after the naturally aspirated version. It uses the Eaton Generation III M90 supercharger with a 3.8 in (97 mm) pulley, a larger throttle body, different fuel injectors, different cylinder heads, and a different lower intake manifold. The L67 and L36 do not share pistons. L67 pistons are heavier and have a different height to lower compression. Both engines share the same engine blocks, but compression is reduced from 9.4:1 in the L36 to 8.5:1 for the L67. GM listed the engine output as 240 hp (179 kW) and 280 lb⋅ft (380 N⋅m) of torque. Final drive ratios are reduced in most applications, for better fuel economy and for improved use of the engine's torque in the low RPM range. Like most 3800 V6s, the engine is well known for its reliability and low maintenance costs. The engine is a popular choice for aftermarket modification thanks to its very strong internals and impressive power gains from basic upgrades. The engine was built in Flint, Michigan, and was certified LEV in 2001.

The Series III engines include many changes. The upper and lower intake manifold is now aluminum on the naturally aspirated models. Intake ports are mildy enlarged; 1.83 in (46.5 mm) intake valves (instead of 1.8 in (45.7 mm) as on Series II) and 1.52 in (38.6 mm) exhaust valves were introduced in 2003 engines, just before switching to Series III. Electronic throttle control is added to all versions, as is returnless fuel injection. Stronger powdered metal sinter forged connecting rods are used in 2004+ supercharged, and 2005+ naturally aspirated engines, instead of the cast iron style from Series II engines. Emissions are also reduced. In 2005, it was the first gasoline engine in the industry to attain SULEV (Super Ultra Low Emissions Vehicle) emissions certification.

Also note that Series III engines are the base for any 3800 produced for the 2004 year and up. This means the same block, heads, and connecting rods apply to any remaining Series II engines made after 2004 also. The difference is that Series III engines received the new superchargers (Generation 5 – Eaton M90 – if equipped), intake manifolds, fuel systems, powdered connecting rods, as well as larger intake valves, drive by wire throttle body and electronics.

 

The L26 is the Series III version of the 3800. It is still a 3.8 L (231 cu in) design. Compression remains at 9.4:1 as with the L36, but the aluminum upper and lower intake (2004+) and stronger connecting rods (2005+) are the primary physical changes. The powdered metal connecting rods were meant to be introduced in 2004 along with the L32, but the GM plant in Bay City, Michigan that supplies the Flint, Michigan plant could not achieve the desired production dates in time for that engine year.

The L32 is a supercharged Series III. Introduced in 2004, the main differences between the L67 and the L32 are the L32's electronic throttle control, slightly improved cylinder head design, and updated Eaton supercharger, the Generation 5 M90. Power output is up to 260 hp (194 kW) in the Grand Prix GTP.

As with the L67, premium fuel (91 octane or higher) is required, but the PCM can compensate for lower octane fuel at the cost of lower power output. The use of below 87 octane fuel can cause detonation that eventually leads to engine damage and failure.

 

Wikimedia Commons has media related to Buick V6 engine.

• Brief early history of the engine
• 3800 history page at CanadianDriver.com