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LT-1 from a 1970 Chevrolet Camaro Z28Years: 1970-1972
The LT-1 was the ultimate 350 cu in (5.7 L) V8, becoming available in 1970. It used solid lifters, 11:1 compression, a high-performance camshaft, and a Holley four-barrel carburetor on a special aluminum intake to produce 370 hp (276 kW) and 380 lb·ft (515 N·m). It was available on the Corvette and Camaro Z28. Power was down in 1971 to 330 hp (246 kW) and 360 lb·ft (488 N·m) with 9:1 compression, and again in 1972 (the last year of the LT-1, now rated using net, rather than gross, measurement) to 255 hp (190 kW) and 280 lb·ft (380 N·m).
The "LT1" designation was later reused on a Generation II GM engine, the LT1.
302
Chevrolet produced a special 302 cu in (4.9 L) engine for Trans Am racing from 1967-1969. It was the product of placing the 3-inch stroke crankshaft into a 4-inch bore block. Although the 283 also used a 3-inch stroke crankshaft, it was a low performance cast iron crankshaft. The crankshaft for the 302 was specially built of forged steel. This engine was used only in the first-generation Camaro Z28. Conservatively rated at 290 hp (216 kW), actual output was around 375 hp (280 kW). This block is one of 3 displacements that underwent a transformation for the 1968/1969 period when the main bearing size was increased from 2.30 in to 2.45 in.
A letter from G.D. Thompson, Chevrolet Engineering Laboratory, dated June 5, 1967 to D.A. Martens, Engineering Department, subject Z-28 Service Pack Power Breakdown states "engine capable of 448 HP will deliver 432HP in full vehicle dress" .... "as installed data corrected to 100 degree brake and 29.52hg dry barometer yields a maximum of 403.8 HP. This correction more closely represents what is available when installed in a vehicle" *bhp@7400rpm
307
A 307 cu in (5 L) version was produced from 1968 through 1973. Engine bore was 3.875 inches (98.4 mm) with a 3.25-inch (82.6 mm) stroke.
The 307 replaced the 283 in Chevrolet cars and produced 200 hp (149 kW) SAE gross at 4600 rpm and 300 lb·ft (407 N·m) of torque at 2400 rpm in the 1960s. The later emissions-modified versions produced just 115 hp (86 kW) SAE net, giving the engine one of the lowest power-per-displacement ratings of all time. Chevrolet never produced a high-performance version of this engine, though they did produce, for Outboard Marine Corporation, a high-performance marinized 307, rated at 235 hp (175 kW) and 245 hp (183 kW) SAE gross, depending on year, that shipped with the Corvette/Z-28's cast aluminum valve covers and Rochester QuadraJet carb. Chevy also built other versions of the OMC 307 rated at 210 hp (157 kW), 215 hp (160 kW) and 225 hp (168 kW) SAE gross.
400
A 400 cu in (6.6 L) small-block was introduced in 1970 and produced for 10 years. It had a 4.125-inch (104.8 mm) bore and a 3.75-inch (95.3 mm) stroke. Initial output was 265 hp (198 kW) and was only available equipped with a 2-barrel carburetor. In 1974 a 4-barrel version of the 400 was introduced,while the 2-barrel version stopped production in 1975. 1976 was the last year that the 400 was used in a Chevrolet Passenger car, available in both the A-Body and B-Body line. While popular with circle-track racers, the engine was prone to cooling troubles if cylinder heads without steam holes were used. They mostly put out 250 hp stock. Due to the way the block was designed, the 2 bolt main engines were stronger than the 4 bolt versions. The 509 2 bolt main block is the most desirable 400 block.
Later Small Blocks
Multiple variations of the original small-block were introduced after 1970's bore-out to 400 cubic inches, many based on the already much modified 350 design. Chronologically, they include:
350 variants
Years: 1973-1980
The 1973-1974 L82 was a "performance" version of the 350 producing 250 hp (186 kW) and 285 lb·ft (386 N·m) from 9:1 compression. It was down to 205 hp (153 kW) and 255 lb·ft (346 N·m) for 1975. It was the optional engine again in 1976-1977, producing 5 hp (4 kW) more. The 1978 L82 recovered somewhat, producing 220 hp (164 kW) and 260 lb·ft (353 N·m), and then 5 hp (4 kW) and 10 lb·ft (14 N·m) more for 1979. 1980 saw yet another 10 hp (7 kW) and 15 lb·ft (20 N·m).
Years: 1981
The L81 was the only 5.7 L (350 cu in) Corvette engine for 1981. It produced 190 hp (142 kW) and 280 lb·ft (380 N·m) from 8.2:1 compression, exactly the same as the 1980 L48, but added computer control spark advance, replacing the vacuum advance.
Years: 1982, 1984
The 1982 L83 was again the only Corvette engine (and only available with an automatic transmission) producing 200 hp (149 kW) and 285 lb·ft (386 N·m) from 9:1 compression. This was again the only engine on the new 1984 Vette, at 205 hp (153 kW) and 290 lb·ft (393 N·m). The L83 added Cross-Fire fuel injection (twin throttle-body fuel injection). Since GM did not assign a 1983 model year to production Corvettes, there was also no L83 for 1983.
For the new Generation IV V8, see GM L98.
Years: 1985-1992
The new 1985 L98 added tuned-port fuel injection "TPI", which produced 230 hp (172 kW) and 330 lb·ft (447 N·m). It was standard on all 1985-1991 Corvettes (rated at 230 hp (172 kW)-250 hp (186 kW) and 330 lb·ft (447 N·m)-350 lb·ft (475 N·m)). Optional on 87-92 Chevrolet Camaro & Pontiac Firebird models (rated at 225 hp (168 kW)-245 hp (183 kW) and 330 lb·ft (447 N·m)-345 lb·ft (468 N·m)) 1987 versions had 10 hp (7 kW) and 15 lb·ft (20 N·m) more thanks to 9.5:1 compression and a change to hydraulic roller camshaft. Compression was up again in 1991 to 10:1 but output stayed the same.
The LM1 is the base 5.7 L (350 cu in) with a 4-barrel carburetor (usually with a Rochester Quadrajet) in passenger cars until 1988. Throughout its lifespan, it received either a points, electronic, and/or computer-controlled spark system, to conventional and feedback carburetors.
LM1s were superseded with the LO5 powerplant after 1988.
The L05 was introduced in 1987 for use in Chevrolet/GMC trucks in both the GMT400 (introduced in April 1987 as 1988 models) and the R/V series trucks such as the K5 Blazer, Suburban, and rounded-era pickups formerly classed as the C/K until 1996 which includes chassis cabs and 4-door crew cabs. Although usage was for trucks, vans, and 9C1-optioned Caprices, the L05 was also used with the following vehicles:
1992/1993 Buick Roadmaster sedan and station wagon
1991/1992 Cadillac Brougham (optional engine)
1993 Cadillac Fleetwood
1992/1993 Chevrolet Caprice Wagon (optional engine)
1993 Chevrolet Caprice LTZ
1992 Oldsmobile Custom Cruiser Wagon (optional engine)
L05 usage was replaced by the GM LT1 after 1993 in GM B-Bodies until production ceased in 1996.
In mid 1996 the L05 was equipped with Vortec heads used in the 1996 G30.
The L31 replaced the LO5 in 1996 - known as the Vortec 5700. Known as the GEN 1+, this was the final incarnation of the 1955-vintage small block, ending production in 2005 with the last vehicle being a Kodiak/Topkick HD truck. Volvo Penta and Mercury Marine still produces the L31. The "MARINE" intake is a potential upgrade for L31 trucks.
Mr. Goodwrench
The GM Goodwrench 350 crate engine comes in several variations. The lowest priced uses the pre-1986 four-bolt casting molds with two dipstick locations; pre-1980 on the driver's side and post-1980 on the passenger's side. This engine was produced in Mexico since 1981 as the Targetmaster 350, and now the GM Goodwrench 350.[citations needed]
262
The 1975-1976 262 was a 262 cu in (4.3 L) 90° pushrod V8 with an iron block and heads. Bore and stroke were 3.67 in (93 mm) by 3.10 in (78.7 mm). Power output for 1975 was 110 hp (82 kW) and 195 lb·ft (264 N·m). The 262 was underpowered and was replaced by the 305 the following year.
This was Chevrolet's second 4.3 L-displacement powerplant; two other Chevrolet engines displaced 4.3 L: the Vortec 4300 (a V6 based on the Chevrolet 350, with two cylinders removed), and a derivative of the LT1 known as the L99 (using the 305's 3.736-inch bore, 5.94-inch connecting rods, and a 3-inch crankshaft stroke).
This engine was used in the following cars:
1975-1976 Chevrolet Monza
1975 Chevrolet Nova
305
The 305 variant of the small-block Chevrolet introduced in 1975 had a displacement of 305 cu in (5 L) with a 3.736-inch (95 mm) bore and 3.48-inch (88.4 mm) stroke. The 262 was considered underpowered for use in vehicles with a wheelbase greater than 110 inches, so GM engineers decided to increase the bore diameter from 3.671 to 3.736 inches (93.2–94.9 mm) and increase the stroke from 3.10 to 3.48 inches (78.7–88.4 mm) (from the 350). Some performance enthusiasts have noted a marked resistance to performance upgrades on the 305 because of its small bore, poor selection of aftermarket cylinder heads, and the relatively high availability of 350 cu in (5.7 L) engines.
Induction systems for the 305 included carburetors (both 2 and 4-barrel), throttle-body injection (TBI), tuned-port fuel injection (TPI), and sequential fuel injection (GM Vortec).
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