Chevrolet 90-Degree V6 engine
Encyclopedia
The Chevrolet
90° V6 family of engines began in 1978 with the Chevrolet
200 cid (3.3 L) V6 as the base engine for the all new 1978 Chevrolet Malibu
. This engine family is still produced today, as the 4.3 L V6 engine used in Chevrolet and GMC trucks and vans.
These engines have a 90° vee block with 12 valves activated by a pushrod valvetrain. All engines have cast iron blocks and cylinder heads. The engines are based on the Chevrolet Small-Block engine
, and the V6 is formed by the removal of the #3 and #6 cylinders. The V6s share the same 4.4" bore spacing and 9.025" deck height as the V8 engines. Many parts are interchangeable between the 90° V6 and the small block V8 including valvetrain components, bearings, piston assemblies, lubrication and cooling system components, and external accessories. The 90-degree V6 engine uses the same transmission bellhousing pattern as the Chevrolet small-block V8 engine. The oil pan dipstick is located on the passenger side above the oil pan rail; this design was phased in on both the V6-90 and Small Block Chevrolet assembly lines sharing the same casting dies. All the engines use a 1-6-5-4-3-2 firing order. The engines in this family are longitudinal engine
s, and have only been used in rear-wheel drive cars and trucks.
Being a 90-degree V6, Chevrolet took steps to eliminate the rough running tendencies of the 200. The crankshaft has each of its connecting rod throws offset by 18 degrees for each pair of rods. This required the connecting rods to have 0.050" narrower ends as well as a thrust bearing to be installed between each pair of rods. However, the connecting rods were still the same 5.7" in length as most other small block Chevrolet V8 engines. This produced an engine that with a semi-even fire sequence of 132 degrees/108 degrees.
The 200 cid V6 was only produced for 1978 and 1979. It was available only with a 2-barrel carburetor. In 1978, the 200 cid used the Rochester 2GC carburetor and in 1979 it used a Rochester Dualjet carburetor. The smaller Dualjet carburetor caused a slight decrease in power.
s and Camaro
s as the new base V6. Additionally, the intermediate Chevrolet Malibu and Monte Carlo also used the 229 cid as a replacement for both the 200 cid V6, and the 231 cid Buick V6
. Both the Buick V6 and the 229 cid Chevrolet V6 are 90 degree V6 engines, and both are often referred to as the 3.8L V6. These engines should not be confused as being the same, and are completely unique engine designs.
The 229 cid has a 3.736" bore and a 3.48" stroke, identical to the Chevrolet 305 cid V8 engine. The 229 cid used the same 2.45" main bearing and 2.10" rod bearing diameters as the 200 cid V6 engine. Also like the 200 cid V6, the 229 cid used the same crankshaft with the 18 degree offset throws and the same 5.7" connecting rods with 0.050" narrowed ends. It came equipped with 1.84" intake valves and 1.50" exhaust valves. The 229 cid V6 was only equipped with a 2-barrel carburetor. For 1980 the 229 cid used a mechanical Dualjet. From 1981 - 1984 the electronic Dualjet was used along with the GM's CCC (Computer Command Control) system. The 229 cid was rated between 110 and 115 hp.
. It also replaced the 250 cid in the Chevrolet full-size trucks and full-size vans as the new base six cylinder engine.
The 4.3L V6 has a 4.00" bore and a 3.48" stroke, identical to the 350 cid Chevrolet V8 engine. To create a true even fire engine, Chevrolet produced a crankshaft with 30 degree offsets between each rod pin. Consequentially, rod journals were increased to a larger 2.25". The connecting rods used on the 4.3L are therefore unique to this engine, being 5.7" in length, but having the larger 2.25" journals. The 4.3L also used larger valves than the 229 cid V6, with a 1.94" intake valve and a 1.50" exhaust valve.
In 1986 and 1987, the 4.3L engine saw engine design upgrades similar to the Chevrolet small block V8. In 1986, the rear main crankshaft oil seal was changed from a two piece to a one piece seal. Some 1985 model year vehicles would have a 1986 engine due to service replacement - cylinder blocks were shipped with oil pans. 1987 saw new center bolt valve covers and hydraulic roller lifters.
For the 1992 model year, the 4.3L had its block design modified to allow a balance shaft
to be installed. Even though the 4.3L is an even fire V6, the 90 degree block layout is not ideal for smoothness. The balance shaft on the 4.3L is installed above the top timing gear, and runs through the top of the lifter valley. It is gear driven off the timing chain, and therefore a new timing chain cover was designed for these balanced 4.3L V6s.
LB4 or a Rochester Quadrajet 4-Barrel carburetor, RPO LB1. The Chevrolet full-size sedans and the Chevrolet El Camino
used the LB4 rated at 130 hp. Pick-ups and Vans used the LB1 version rated at 155 hp. The LB1 used in trucks and vans was referred to as Vortec in Chevrolet literature (named after a combustion chamber design known as a swirl port which twists the fuel mix from the intake ports as introduced on the Cavalier 2.0L motor), and this name continued to be used with all truck and van 4.3L V6s until present day.
In 1986, the 4.3L engine used in the Chevrolet Caprice
and El Camino saw an increase in power to 140 hp. This engine remained unchanged until 1990 when it was last used in taxi and Police Chevrolet Caprices. In 1986 the Chevrolet Astro and GMC Safari vans used the fuel injected LB4 instead of the LB1. In 1987, the Chevrolet full size pick-ups and full-size vans were upgraded to use the LB4 throttle-body injection version of the 4.3L. From 1987 onwards LB4s output was 160 hp for pickups, while full-size vans were rated at 150 hp. In 1988 the S-series trucks and S-Blazer and Jimmys had the LB4 4.3L as an available option (the accessory drive was upgraded to a serpentine belt drive), which later replaced the 2.8 as the base V6. The LB4 continued until 1996 with minor variations in power, but without any major change.
Legend
Legend
and Astro
and Safari vans only. The L35 was rated at 200 hp and 260 ft-lb (352.5 N·m) of torque.
The cylinder block was redesigned for use with a balance shaft
.
Legend
The engine block was revised with structural reinforcing ribs up front eliminating the two freeze plugs (on the front and back) along with an alloy oil pan (for the S10, Blazer, and Jimmy).
This engine came in two versions, the LF6 rated at 175 hp - 180 hp, and the L35 rated at 180 - 200 hp. Only the S-series pick-ups used the LF6, while the full-size trucks, vans and Blazer and Jimmy used the L35 version. The L35 was optional on the S-Series trucks.
Legend
s, GMC Safaris, Chevrolet Silverado
s and GMC Sierras all came equipped with the updated LU3 4.3L. 2003 saw the L35 discontinued and the LU3 replacing it in all other applications. A new variation was also introduced in 2003, the LG3. For 2004 to 2009 the LU3 has been the only 4.3L produced.
The biggest change to the LU3 and LG3 was the fuel injection system. These engines used a multipoint fuel injection system, with six Multec II fuel injectors mounted at each intake port on the manifold. The composite upper intake manifold and cast aluminum lower intake from the L35 engine is also used on the LU3. The LG3 uses a cast aluminum upper intake and a cast iron lower intake.
The LU3 also received a quiet cam to help reduce vibration at both idle and high engine speeds. This camshaft used the same lift and duration as the older design, but the cam was reprofiled to keep the valve lifters in full contact with the cam lobes as the cam ramps down.
The LG3 was used in Chevrolet and GMC S-series pickups and was only produced for 2003. The LU3 was used in the Chevrolet and GMC full-size trucks and vans, the Chevrolet Astro and GMC Safari vans and the Chevrolet S-10 Blazer and GMC S-15 Jimmy. The LG3 was rated at 180 hp and 245 ft.lbf of torque. The LU3 was rated at 190-200 hp and 250–260 ft·lbf of torque.
Legend
limited edition truck that used a turbocharged 4.3L V6. This engine used a Mitsubishi TD06-17C turbocharger, Garrett Water/Air intercooler and electronic multi-point fuel injection. Although GM made these modifications to the engine, it was still referred to with the RPO LB4 code. The majority of the natuarally aspired LB4's long-block was shared with the turbo version. However, the vehicles that used the 4.3L turbo engine also included RPO code ZR9. Internal engine upgrades included nodular iron main bearing caps, graphite composite head gaskets with stainless steel flanges and hypereutectic piston
s which lowered the engine compression to 8.35:1. A unique intake manifold that used the 48 mm (1.9 in) twin-bore throttle body from the 5.7L TPI Corvette engine was used on the engine's top end.
The Turbocharged 4.3L was last used in the GMC Typhoon
in the 1993 model year. The engine produced 280 hp @ 4400 rpm and 360 ft.lbf of torque @ 3600 rpm.
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
90° V6 family of engines began in 1978 with the Chevrolet
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
200 cid (3.3 L) V6 as the base engine for the all new 1978 Chevrolet Malibu
Chevrolet Malibu
Malibus and all other Chevelles were completely restyled for 1968 with semi-fastback rooflines on two-door hardtops and wheelbases split to on two-door models and 118 for four-door sedans and station wagons. Engine offerings included a new V8 rated at that replaced the V8 that had served as the...
. This engine family is still produced today, as the 4.3 L V6 engine used in Chevrolet and GMC trucks and vans.
These engines have a 90° vee block with 12 valves activated by a pushrod valvetrain. All engines have cast iron blocks and cylinder heads. The engines are based on the Chevrolet Small-Block engine
Chevrolet Small-Block engine
The Chevrolet small-block engine is a series of automobile V8 engines built by the Chevrolet Division of General Motors using the same basic small engine block...
, and the V6 is formed by the removal of the #3 and #6 cylinders. The V6s share the same 4.4" bore spacing and 9.025" deck height as the V8 engines. Many parts are interchangeable between the 90° V6 and the small block V8 including valvetrain components, bearings, piston assemblies, lubrication and cooling system components, and external accessories. The 90-degree V6 engine uses the same transmission bellhousing pattern as the Chevrolet small-block V8 engine. The oil pan dipstick is located on the passenger side above the oil pan rail; this design was phased in on both the V6-90 and Small Block Chevrolet assembly lines sharing the same casting dies. All the engines use a 1-6-5-4-3-2 firing order. The engines in this family are longitudinal engine
Longitudinal engine
In automotive engineering, a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back....
s, and have only been used in rear-wheel drive cars and trucks.
3.3L (200 CID)
Introduced in 1978, the 200 cid replaced the larger 250 cid as the base engine for Chevrolet's new downsized intermediate line. The 200 cid used a unique 3.5" bore and a 3.48" stroke (the Chevrolet 305 cid and 350 cid V8 engines shared the same stroke dimension). These bore and stroke dimensions were later used by the 267 cid V8 Cheverolet engine. Also like the small block V8 engines, the 200 cid V6 used 2.45" main bearings and 2.10" rod bearing diameters.Being a 90-degree V6, Chevrolet took steps to eliminate the rough running tendencies of the 200. The crankshaft has each of its connecting rod throws offset by 18 degrees for each pair of rods. This required the connecting rods to have 0.050" narrower ends as well as a thrust bearing to be installed between each pair of rods. However, the connecting rods were still the same 5.7" in length as most other small block Chevrolet V8 engines. This produced an engine that with a semi-even fire sequence of 132 degrees/108 degrees.
The 200 cid V6 was only produced for 1978 and 1979. It was available only with a 2-barrel carburetor. In 1978, the 200 cid used the Rochester 2GC carburetor and in 1979 it used a Rochester Dualjet carburetor. The smaller Dualjet carburetor caused a slight decrease in power.
| Year | Horsepower | Torque | Bore and Stroke | Carburetor | Compression Ratio |
|---|---|---|---|---|---|
| 1978 | 95 hp @ 3800 rpm | 160 lbft @2000 rpm | 3.50" x 3.48" | 2-BBL 2GC | 8.20:1 |
| 1979 | 94 hp @ 4000 rpm | 154 lbft @2000 rpm | 3.50" x 3.48" | 2-BBL M2ME | 8.20:1 |
3.8L (229 CID)
The 229 cid (3,751 cc) engine was first introduced for the 1980 model year and was produced until 1984. This engine replaced the 250 cid in full-size ChevroletChevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
s and Camaro
Chevrolet Camaro
The Chevrolet Camaro is an automobile manufactured by General Motors under the Chevrolet brand, classified as a pony car and some versions also as a muscle car. It went on sale on September 29, 1966, for the 1967 model year and was designed as a competing model to the Ford Mustang...
s as the new base V6. Additionally, the intermediate Chevrolet Malibu and Monte Carlo also used the 229 cid as a replacement for both the 200 cid V6, and the 231 cid Buick V6
Buick V6 engine
The Buick V6, initially marketed as Fireball at its introduction in 1962, was a large V6 engine used by General Motors. The block is made of cast iron and all use two-valve-per-cylinder iron heads, actuated by pushrods....
. Both the Buick V6 and the 229 cid Chevrolet V6 are 90 degree V6 engines, and both are often referred to as the 3.8L V6. These engines should not be confused as being the same, and are completely unique engine designs.
The 229 cid has a 3.736" bore and a 3.48" stroke, identical to the Chevrolet 305 cid V8 engine. The 229 cid used the same 2.45" main bearing and 2.10" rod bearing diameters as the 200 cid V6 engine. Also like the 200 cid V6, the 229 cid used the same crankshaft with the 18 degree offset throws and the same 5.7" connecting rods with 0.050" narrowed ends. It came equipped with 1.84" intake valves and 1.50" exhaust valves. The 229 cid V6 was only equipped with a 2-barrel carburetor. For 1980 the 229 cid used a mechanical Dualjet. From 1981 - 1984 the electronic Dualjet was used along with the GM's CCC (Computer Command Control) system. The 229 cid was rated between 110 and 115 hp.
| Year | Horsepower | Torque | Bore and Stroke | Carburetor | Compression Ratio |
|---|---|---|---|---|---|
| 1980 | 115 hp at 4,000 rpm | 175 lbft at 2,000 rpm | 3.736" x 3.48" | 2-BBL M2ME | 8.60:1 |
| 1981–1982 | 110 hp at 4,200 rpm | 170 lbft at 2,000 rpm | 3.736" x 3.48" | 2-BBL E2ME | 8.60:1 |
| 1983–1984 | 110 hp at 4,000 rpm | 190 lbft at 1,600 rpm | 3.736" x 3.48" | 2-BBL E2ME | 8.60:1 |
4.3L (262 CID)
The 4.3L (262 cid) V6 is the last and most successful engine in the Chevrolet 90-degree V6 engine family. This engine was introduced in 1985 as a replacement for the 229 cid V6 in the full-size Chevrolet and the Chevrolet El CaminoChevrolet El Camino
The Chevrolet El Camino is a coupe utility vehicle produced by the Chevrolet division of General Motors for the 1959–1960 model years in response to the success of its rival, Ford Ranchero. Production resumed for the 1964–1977 model years based on the Chevelle platform, and continued for the...
. It also replaced the 250 cid in the Chevrolet full-size trucks and full-size vans as the new base six cylinder engine.
The 4.3L V6 has a 4.00" bore and a 3.48" stroke, identical to the 350 cid Chevrolet V8 engine. To create a true even fire engine, Chevrolet produced a crankshaft with 30 degree offsets between each rod pin. Consequentially, rod journals were increased to a larger 2.25". The connecting rods used on the 4.3L are therefore unique to this engine, being 5.7" in length, but having the larger 2.25" journals. The 4.3L also used larger valves than the 229 cid V6, with a 1.94" intake valve and a 1.50" exhaust valve.
In 1986 and 1987, the 4.3L engine saw engine design upgrades similar to the Chevrolet small block V8. In 1986, the rear main crankshaft oil seal was changed from a two piece to a one piece seal. Some 1985 model year vehicles would have a 1986 engine due to service replacement - cylinder blocks were shipped with oil pans. 1987 saw new center bolt valve covers and hydraulic roller lifters.
For the 1992 model year, the 4.3L had its block design modified to allow a balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...
to be installed. Even though the 4.3L is an even fire V6, the 90 degree block layout is not ideal for smoothness. The balance shaft on the 4.3L is installed above the top timing gear, and runs through the top of the lifter valley. It is gear driven off the timing chain, and therefore a new timing chain cover was designed for these balanced 4.3L V6s.
LB1 and LB4
In 1985, the 4.3L was either equipped with throttle-body fuel injection, RPORegular Production Option
A Regular Production Option is a General Motors standard coding for vehicle configuration options. These codes are a combination of 3 alphanumeric characters and refer to a specific option or modification to the vehicle...
LB4 or a Rochester Quadrajet 4-Barrel carburetor, RPO LB1. The Chevrolet full-size sedans and the Chevrolet El Camino
Chevrolet El Camino
The Chevrolet El Camino is a coupe utility vehicle produced by the Chevrolet division of General Motors for the 1959–1960 model years in response to the success of its rival, Ford Ranchero. Production resumed for the 1964–1977 model years based on the Chevelle platform, and continued for the...
used the LB4 rated at 130 hp. Pick-ups and Vans used the LB1 version rated at 155 hp. The LB1 used in trucks and vans was referred to as Vortec in Chevrolet literature (named after a combustion chamber design known as a swirl port which twists the fuel mix from the intake ports as introduced on the Cavalier 2.0L motor), and this name continued to be used with all truck and van 4.3L V6s until present day.
In 1986, the 4.3L engine used in the Chevrolet Caprice
Chevrolet Caprice
The Chevrolet Caprice is a full-sized automobile produced by the Chevrolet Division of General Motors in North America for the 1965 through 1996 model years. Full-size Chevrolet sales peaked in 1965 with over a million sold. It was the most popular American car in the sixties and early seventies....
and El Camino saw an increase in power to 140 hp. This engine remained unchanged until 1990 when it was last used in taxi and Police Chevrolet Caprices. In 1986 the Chevrolet Astro and GMC Safari vans used the fuel injected LB4 instead of the LB1. In 1987, the Chevrolet full size pick-ups and full-size vans were upgraded to use the LB4 throttle-body injection version of the 4.3L. From 1987 onwards LB4s output was 160 hp for pickups, while full-size vans were rated at 150 hp. In 1988 the S-series trucks and S-Blazer and Jimmys had the LB4 4.3L as an available option (the accessory drive was upgraded to a serpentine belt drive), which later replaced the 2.8 as the base V6. The LB4 continued until 1996 with minor variations in power, but without any major change.
| Year | Horsepower | Torque | Fuel System | Compression Ratio | RPO | Applications |
|---|---|---|---|---|---|---|
| 1985–1986 | 155 hp @ 4000 rpm | 230 lbft @ 2400 RPM | 4-BBL | 9.3:1 | LB1 | 1,2,3 |
| 1985 | 130 hp @ 3600 rpm | 210 lbft @ 2000 RPM | TBI | 9.3:1 | LB4 | 4,5 |
| 1986–1990 | 140 hp @ 4000 rpm | 225 lbft @ 2000 RPM | TBI | 9.3:1 | LB4 | 4,5 |
| 1987–1988 | 145 hp @ 4200 rpm | 225 lbft @ 2000 RPM | TBI | 9.3:1 | LB4 | 5 |
| 1986 | 160 hp @ 4000 rpm | 235 lbft @ 2400 RPM | TBI | 9.3:1 | LB4 | 3 |
| 1987–1992 | 155 hp @ 4000 rpm | 230 lbft @ 2400 RPM | TBI | 8.6:1 | LB4(w/C6P emissions 2500&3500 series only) | 2 |
| 1987–1992 | 160 hp @ 4000 rpm | 235 lbft @ 2400 RPM | TBI | 9.1:1 | LB4 | 1,3,6,7 |
| 1993–1995 | 155 hp @ 4000 rpm | 230 lbft @ 2000 RPM | TBI | 9.1:1 | LB4 | 2 |
| 1993–1995 | 165 hp @ 4000 rpm | 235 lbft @ 2000 RPM | TBI | 9.1:1 | LB4 | 1,3,6,7 |
Legend
- 1 - Chevrolet C/KChevrolet C/KThe C/K is the name for Chevrolet and GMC's full-size pickup truck line from 1960 until 1999 in the United States, from 1965 to 1999 Canada, from 1964 through 2001 in Brazil, and from 1975 to 1982 in Chile. The first Chevrolet pickup truck appeared in 1924, though in-house designs did not appear...
Trucks, GMC C/KChevrolet C/KThe C/K is the name for Chevrolet and GMC's full-size pickup truck line from 1960 until 1999 in the United States, from 1965 to 1999 Canada, from 1964 through 2001 in Brazil, and from 1975 to 1982 in Chile. The first Chevrolet pickup truck appeared in 1924, though in-house designs did not appear...
Trucks - 2 - Chevrolet G-Series VansChevrolet VanThe Chevrolet and GMC G-Series vans were made by General Motors for North America. They are in the same vehicle class as the Ford Econoline van and the Dodge Ram Van.The term "Chevrolet van" also refers to the entire series of vans sold by Chevrolet...
, GMC G-Series Vans - 3 - Chevrolet AstroChevrolet AstroThe Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
vans, GMC Safari Vans - NOTE - LB1 for 1985 only & LB4 not available 1995 - 4 - 1985 Chevrolet ImpalaChevrolet ImpalaThe Chevrolet Impala is a full-size automobile built by the Chevrolet division of General Motors introduced for the 1958 model year. Deriving its name from the southern African antelope, Chevrolet's most expensive passenger model through 1965 had become the best-selling automobile in the United...
, 1985–1988 Chevrolet CapriceChevrolet CapriceThe Chevrolet Caprice is a full-sized automobile produced by the Chevrolet Division of General Motors in North America for the 1965 through 1996 model years. Full-size Chevrolet sales peaked in 1965 with over a million sold. It was the most popular American car in the sixties and early seventies....
, 1989–1990 Chevrolet Caprice Police/Taxi only, 1985–1986 Pontiac ParisiennePontiac ParisienneThe Pontiac Parisienne is a full-size rear-wheel drive vehicle that was sold by Pontiac on the GM B platform in Canada from 1958 to 1986 and in the US from 1983 to 1986... - 5 - 1985–1988 Chevrolet El CaminoChevrolet El CaminoThe Chevrolet El Camino is a coupe utility vehicle produced by the Chevrolet division of General Motors for the 1959–1960 model years in response to the success of its rival, Ford Ranchero. Production resumed for the 1964–1977 model years based on the Chevelle platform, and continued for the...
, GMC CaballeroGMC CaballeroThe GMC Sprint is a coupe utility that was produced by the GMC division of General Motors for the 1971–1977 model years. The Sprint was renamed Caballero for the 1978 model year and was produced through 1987. The rear-wheel-drive car based pick-ups were sold by GMC Truck dealers mainly in the...
, Chevrolet Monte CarloChevrolet Monte CarloThe Chevrolet Monte Carlo was an American-made two-door coupe introduced for model year 1970, and manufactured over six generations through model year 2007. It was marketed as a personal-luxury coupe through most of its history, with the last model version being classified as a full-sized coupe...
, 1986–1987 Pontiac Grand PrixPontiac Grand PrixPicking up where the Pontiac Ventura model left off, the Grand Prix first appeared in the Pontiac line for 1962. It was essentially a standard Pontiac Catalina coupe with minimal outside chrome trim and a sportier interior...
- NOTE - 140 hp LB4 used 1986 only - 6 - 1988–1994 Chevrolet S-10 BlazerChevrolet S-10 BlazerThe Chevrolet Blazer and the similar GMC S-15 Jimmy are mid-size SUVs from General Motors. Production began alongside the larger K5 Blazer and Jimmy in 1983 and lasted through 2005. In the United States retail sales after 2004 were limited to two-door Blazer models, all other models being sold...
, GMC S-15 Jimmy and 1991 Oldsmobile BravadaOldsmobile BravadaThe Oldsmobile Bravada is a mid-size luxury sport utility vehicle from the now retired Oldsmobile marque of General Motors. There have been two different vehicles to bear this model name, the first and second-generation GMT330, and the 2002 to 2004 GMT360.... - 7 - 1988–1995 Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC S-15 Sonoma
LU2
For the 1990-1991 model years a high output 4.3L V6 was an available option for the Chevrolet Astro and GMC Safari vans. The LU2 used unique hypereutectic, strutless pistons and a more aggressive camshaft. Like the LB4, the LU2 used throttle-body fuel injection, but was rated at 170 hp and 260 ft.lbf of torque. This engine was replaced in 1992 with the L35.| Year | Horsepower | Torque | Fuel System | Compression Ratio | RPO | Applications |
|---|---|---|---|---|---|---|
| 1990–1992 | 170 hp @ 4600 rpm | 260 lbft @ 3400 RPM | TBI | 9.1:1 | LU2 | 1 |
Legend
- 1 - Chevrolet AstroChevrolet AstroThe Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
vans, GMC Safari Vans - optional on extended length models
L35 CPI
1992 introduced a new version of the 4.3L, the L35. This version of the 4.3L was equipped with CPI (Central Port Fuel Injection). This system had one centrally located fuel injector to distribute fuel to six hoses each with a poppet valve to each of the intake ports. This system allowed for a multi-point injection, using one injector. The fuel injection was a batch fire system and used a two piece cast aluminum dual-plenum manifold. This engine was available in S-10 Blazers/Pickups and S15-JimmysChevrolet S-10 Blazer
The Chevrolet Blazer and the similar GMC S-15 Jimmy are mid-size SUVs from General Motors. Production began alongside the larger K5 Blazer and Jimmy in 1983 and lasted through 2005. In the United States retail sales after 2004 were limited to two-door Blazer models, all other models being sold...
and Astro
Chevrolet Astro
The Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
and Safari vans only. The L35 was rated at 200 hp and 260 ft-lb (352.5 N·m) of torque.
The cylinder block was redesigned for use with a balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...
.
| Year | Horsepower | Torque | Fuel System | Compression Ratio | RPO | Applications |
|---|---|---|---|---|---|---|
| 1992–1994 | 200 hp at 4,500 rpm | 260 lbft at 3,600 rpm | CPI | 9.1:1 | L35 | 1,2,3 |
| 1995 | 190 hp at 4,500 rpm | 260 lbft at 3,400 rpm | CPI | 9.1:1 | L35 | 1 |
| 1995 | 191 hp at 4,500 rpm | 260 lbft at 3,400 rpm | CPI | 9.1:1 | L35 | 3 |
| 1995 | 195 hp at 4,500 rpm | 260 lbft at 3,400 rpm | CPI | 9.1:1 | L35 | 2 |
Legend
- 1 - Chevrolet AstroChevrolet AstroThe Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
vans, GMC Safari Vans - NOTE std on AWD, opt on 2WD models - 2 - Chevrolet S-10 BlazerChevrolet S-10 BlazerThe Chevrolet Blazer and the similar GMC S-15 Jimmy are mid-size SUVs from General Motors. Production began alongside the larger K5 Blazer and Jimmy in 1983 and lasted through 2005. In the United States retail sales after 2004 were limited to two-door Blazer models, all other models being sold...
, GMC Jimmy and Oldsmobile BravadaOldsmobile BravadaThe Oldsmobile Bravada is a mid-size luxury sport utility vehicle from the now retired Oldsmobile marque of General Motors. There have been two different vehicles to bear this model name, the first and second-generation GMT330, and the 2002 to 2004 GMT360....
- NOTE - Oldsmobile Bravada not produced in 1995 - 3 - Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC Sonoma
L35 and LF6 SCPI
Major design changes to the 4.3L V6 for the 1996 model year. Like other small block Chevrolet V8s, the 4.3L engine received redesigned heads which had improved airflow and combustion efficiency. These heads are referred to as Vortec heads. Furthermore the 4.3L was upgraded to receive sequential port fuel injection. The fuel system uses six centrally mounted injectors firing into six nylon hoses with poppet valves leading to each intake port. This system was call SCPI (Sequential Central Port Injection). This 4.3L used a two piece manifold, with the upper half manufactured from a composite plastic and the lower half manufactured from cast aluminum.The engine block was revised with structural reinforcing ribs up front eliminating the two freeze plugs (on the front and back) along with an alloy oil pan (for the S10, Blazer, and Jimmy).
This engine came in two versions, the LF6 rated at 175 hp - 180 hp, and the L35 rated at 180 - 200 hp. Only the S-series pick-ups used the LF6, while the full-size trucks, vans and Blazer and Jimmy used the L35 version. The L35 was optional on the S-Series trucks.
| Year | Horsepower | Torque | Fuel System | Compression Ratio | RPO | Applications |
|---|---|---|---|---|---|---|
| 1996 | 170 hp at 4,400 rpm | 235 lbft at 2,800 rpm | SCPI | 9.2:1 | LF6 | 5 |
| 1997–2002 | 175 hp at 4,400 rpm | 240 lbft at 2,800 rpm | SCPI | 9.2:1 | LF6 | 5 |
| 1996–2002 | 180 hp at 4,400 rpm | 240 lbft at 2,800 rpm | SCPI | 9.2:1 | LF6 | 6 |
| 1996–2002 | 180 hp at 4,400 rpm | 245 lbft at 2,800 rpm | SCPI | 9.2:1 | L35 | 5 |
| 1996–2002 | 190 hp at 4,400 rpm | 250 lbft at 2,800 rpm | SCPI | 9.2:1 | L35 | 3,4,6 |
| 1996–2002 | 200 hp at 4,400 rpm | 250 lbft at 2,800 rpm | SCPI | 9.2:1 | L35 | 2 |
| 1996–1998 | 200 hp at 4,400 rpm | 255 lbft at 2,800 rpm | SCPI | 9.2:1 | L35 | 1 |
| 1999–2002 | 200 hp at 4,600 rpm | 260 lbft at 2,800 rpm | SCPI | 9.2:1 | L35 | 7 |
Legend
- 1 - Chevrolet C/KChevrolet C/KThe C/K is the name for Chevrolet and GMC's full-size pickup truck line from 1960 until 1999 in the United States, from 1965 to 1999 Canada, from 1964 through 2001 in Brazil, and from 1975 to 1982 in Chile. The first Chevrolet pickup truck appeared in 1924, though in-house designs did not appear...
Trucks, GMC C/KChevrolet C/KThe C/K is the name for Chevrolet and GMC's full-size pickup truck line from 1960 until 1999 in the United States, from 1965 to 1999 Canada, from 1964 through 2001 in Brazil, and from 1975 to 1982 in Chile. The first Chevrolet pickup truck appeared in 1924, though in-house designs did not appear...
Trucks - 2 - Chevrolet ExpressChevrolet ExpressThe Chevrolet Express and GMC Savana are full-size vans from General Motors. They replaced the Chevrolet Van and GMC Vandura in 1996. The Express and Savana currently hold 44.8% of the full-size van market in the United States, just behind rival Ford's E-Series...
, GMC Savana Vans - 3 - Chevrolet AstroChevrolet AstroThe Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
vans, GMC Safari Vans - 4 - Chevrolet BlazerChevrolet S-10 BlazerThe Chevrolet Blazer and the similar GMC S-15 Jimmy are mid-size SUVs from General Motors. Production began alongside the larger K5 Blazer and Jimmy in 1983 and lasted through 2005. In the United States retail sales after 2004 were limited to two-door Blazer models, all other models being sold...
, GMC Jimmy, 1996–2001 Oldsmobile BravadaOldsmobile BravadaThe Oldsmobile Bravada is a mid-size luxury sport utility vehicle from the now retired Oldsmobile marque of General Motors. There have been two different vehicles to bear this model name, the first and second-generation GMT330, and the 2002 to 2004 GMT360.... - 5 - Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC Sonoma (2WD) - 6 - Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC Sonoma (4WD) - 7 - Chevrolet SilveradoChevrolet SilveradoThe Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
and GMC Sierra trucks
LU3 and LG3 MPFI
2002 saw major changes to the 4.3L fuel injection system. For 2002 California emission Chevrolet AstroChevrolet Astro
The Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
s, GMC Safaris, Chevrolet Silverado
Chevrolet Silverado
The Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
s and GMC Sierras all came equipped with the updated LU3 4.3L. 2003 saw the L35 discontinued and the LU3 replacing it in all other applications. A new variation was also introduced in 2003, the LG3. For 2004 to 2009 the LU3 has been the only 4.3L produced.
The biggest change to the LU3 and LG3 was the fuel injection system. These engines used a multipoint fuel injection system, with six Multec II fuel injectors mounted at each intake port on the manifold. The composite upper intake manifold and cast aluminum lower intake from the L35 engine is also used on the LU3. The LG3 uses a cast aluminum upper intake and a cast iron lower intake.
The LU3 also received a quiet cam to help reduce vibration at both idle and high engine speeds. This camshaft used the same lift and duration as the older design, but the cam was reprofiled to keep the valve lifters in full contact with the cam lobes as the cam ramps down.
The LG3 was used in Chevrolet and GMC S-series pickups and was only produced for 2003. The LU3 was used in the Chevrolet and GMC full-size trucks and vans, the Chevrolet Astro and GMC Safari vans and the Chevrolet S-10 Blazer and GMC S-15 Jimmy. The LG3 was rated at 180 hp and 245 ft.lbf of torque. The LU3 was rated at 190-200 hp and 250–260 ft·lbf of torque.
| Year | Horsepower | Torque | Fuel System | Compression Ratio | RPO | Applications |
|---|---|---|---|---|---|---|
| 2003 | 180 hp at 4,400 rpm | 245 lbft at 2,800 rpm | MPFI | 9.2:1 | LG3 | 5 |
| 2003–2005 | 190 hp at 4,400 rpm | 250 lbft at 2,800 rpm | MPFI | 9.2:1 | LU3 | 3,4,6 |
| 2002–2003 | 200 hp at 4,400 rpm | 250 lbft at 2,800 rpm | MPFI | 9.2:1 | LU3 | 2 |
| 2002–2003 | 200 hp at 4,600 rpm | 260 lbft at 2,800 rpm | MPFI | 9.2:1 | LU3 | 1 |
| 2004–2009 | 195 hp at 4,600 rpm | 260 lbft at 2,800 rpm | MPFI | 9.2:1 | LU3 | 1,2 |
Legend
- 1 - Chevrolet SilveradoChevrolet SilveradoThe Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
and GMC Sierra trucks - 2 - Chevrolet ExpressChevrolet ExpressThe Chevrolet Express and GMC Savana are full-size vans from General Motors. They replaced the Chevrolet Van and GMC Vandura in 1996. The Express and Savana currently hold 44.8% of the full-size van market in the United States, just behind rival Ford's E-Series...
, GMC Savana Vans - 3 - Chevrolet AstroChevrolet AstroThe Chevrolet Astro was a rear-wheel drive mid-sized van introduced by Chevrolet in 1985 to rival domestic competitors the Dodge Caravan/Plymouth Voyager twins and the Japanese Toyota Van. Also sharing the Astro's platform was its sibling, the GMC Safari...
vans, GMC Safari Vans - 4 - Chevrolet BlazerChevrolet S-10 BlazerThe Chevrolet Blazer and the similar GMC S-15 Jimmy are mid-size SUVs from General Motors. Production began alongside the larger K5 Blazer and Jimmy in 1983 and lasted through 2005. In the United States retail sales after 2004 were limited to two-door Blazer models, all other models being sold...
and GMC Jimmy - 5 - Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC Sonoma (2WD) - 6 - Chevrolet S-10Chevrolet S-10The first compact pickup from General Motors was the rebadged Isuzu KB sold since 1972 as the Chevrolet LUV. The 1973 Arab oil embargo forced GM to consider designing a domestically-produced compact pickup truck. As usual, parts from other GM chassis lines were incorporated. The first S-series...
and GMC Sonoma (4WD)
Turbocharged LB4 4.3L V6
In 1991 GMC introduced the GMC SycloneGMC Syclone
The GMC Syclone is a high-performance version of the GMC Sonoma pickup truck. Produced in 1991, the Syclone spawned the similarly powered 1992-1993 GMC Typhoon SUV. Another vehicle, the GMC Sonoma GT, offered less performance but was seen as a companion model.At the time it was introduced, the...
limited edition truck that used a turbocharged 4.3L V6. This engine used a Mitsubishi TD06-17C turbocharger, Garrett Water/Air intercooler and electronic multi-point fuel injection. Although GM made these modifications to the engine, it was still referred to with the RPO LB4 code. The majority of the natuarally aspired LB4's long-block was shared with the turbo version. However, the vehicles that used the 4.3L turbo engine also included RPO code ZR9. Internal engine upgrades included nodular iron main bearing caps, graphite composite head gaskets with stainless steel flanges and hypereutectic piston
Hypereutectic piston
A hypereutectic piston is an internal combustion engine piston cast using a hypereutectic alloy–that is, a metallic alloy which has a composition beyond the eutectic point. Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminum at the...
s which lowered the engine compression to 8.35:1. A unique intake manifold that used the 48 mm (1.9 in) twin-bore throttle body from the 5.7L TPI Corvette engine was used on the engine's top end.
The Turbocharged 4.3L was last used in the GMC Typhoon
GMC Typhoon
The GMC Typhoon is a high-performance version of the GMC Jimmy SUV. Produced in 1992 and 1993, the Typhoon was based on the 1991 GMC Jimmy SUV....
in the 1993 model year. The engine produced 280 hp @ 4400 rpm and 360 ft.lbf of torque @ 3600 rpm.