Chevrolet Big-Block engine
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While most General Motors divisions simply created tall-deck versions of their V8 engines, Chevrolet created a new big-block design for large-displacement use. Cadillac also had a special big-block design.
Chevrolet's "W Series" engine was a flathead design with no shaped combustion chamber. Each bank of cylinders shared the same head design, with the compression ratio varied by the piston shape rather than the cylinder head. Ford's MEL engine also used this design.
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Generation 1
The first big-block V8 family from Chevrolet was introduced in 1958 and produced through 1965. It was used in Chevrolet cars and trucks.
All first-generation engines used cast iron engine blocks and two-bolt main bearing caps. One change between the 348 and 409/427 was the location of the dipstick: It is on the driver's side on the former and opposite on the latter. The cylinder heads are all similar, apart from the larger valves used on the larger engines.
The first-generation big blocks had a dry weight (without oil or coolant) of approximately 665 lb (300 kg), depending on manifold and carburetion.
348
The first big-block, by GM's reckoning, was the 1958 "Turbo-Thrust" 348 in³ (5.7 L) originally intended for use in Chevrolet trucks, but also introduced in the larger, heavier 1958 passenger car line. Bore was 4.125 in (104.8 mm) and stroke was 3.25 in (82.5 mm). This engine was replaced by the 409 as Chevrolet's top engine in 1961 and went out of production for cars at the end of that year. It was produced through 1965 in large Chevrolet trucks.
The base Turbo-Thrust, with a four-barrel carburetor, produced 250 hp (186 kW). A special "Tri-Power" triple-two-barrel version, called the "Super Turbo-Thrust" produced 280 hp (209 kW). A "Special Turbo-Thrust" upped the output to 305 hp (227 kW) with a single large four-barrel. Mechanical lifters and the Tri-Power carb brought the "Special Super Turbo-Thrust" up to 315 hp (235 kW). For 1959, high-output versions of the top two engines were produced with 320 hp (239 kW) and 335 hp (250 kW) respectively. Even higher-output versions appeared the next year, at 340 hp (253 kW) and 350 hp (261 kW).
Versions:
| First Year | Last Year | Model Name | Features | Power |
|---|---|---|---|---|
| 1958 | 1961 | Turbo-Thrust | 4 barrel | 250 hp (186 kW) |
| 1958 | 1961 | Super Turbo-Thrust | "Tri-Power" 3x2 barrel | 280 hp (209 kW) |
| 1958 | 1961 | Special Turbo-Thrust | 4 barrel | 305 hp (227 kW) |
| 1958 | 1960 | Special Super Turbo-Thrust | "Tri-Power" 3x2 barrel | 315 hp (235 kW) |
| 1959 | 1960 | Special Turbo-Thrust | 4 barrel | 320 hp (239 kW) |
| 1959 | 1961 | Special Super Turbo-Thrust | "Tri-Power" 3x2 barrel | 335 hp (250 kW) |
| 1960 | 1961 | Special Turbo-Thrust | 4 barrel | 340 hp (253 kW) |
| 1960 | 1961 | Special Super Turbo-Thrust | "Tri-Power" 3x2 barrel | 350 hp (261 kW) |
409
A 409 in³ version was Chevrolet's top regular production engine from 1961 to 1964, with a choice of single- or dual-four-barrel carburetors. Output reached 409 hp (305 kW), one hp per cubic inch, in 1962. The "Tri-Power" was never offered on the 409.
Bore and stroke were both up from the 348 at 4.312 in (109.5 mm) by 3.50 in (88.9 mm). The engine was available through mid 1965.
Versions:
| First Year | Last Year | Model Name | Features | Power |
|---|---|---|---|---|
| 1961 | 1961 | 4 barrel | 360 hp (269 kW) | |
| 1962 | 1965 | 4 barrel | 380 hp (283 kW) | |
| 1962 | 1964 | 2x4 barrel | 409 hp (305 kW) |
Z11 427
A special Z11 427 in³ (7.0 L) version of the 409 was used in the 1963 Chevrolet Impala Sports Coupe. Unlike the later 427, it was a basic W-Series 409 engine but with a longer 3.65 in (92.7 mm) stroke. An aluminum intake manifold and dual Carter AFB carbs fed a 13.5:1 compression ratio to produce an under-rated 430 hp (321 kW) and 435 ft·lbf (590 N·m). 50 Z11s were produced.
Generation 2
Development of the automobile big-block started with the Mystery Motor used in Chevrolet's 1963 Daytona 500 stock cars. The "secret" motor was released in mid 1965 as the Mark IV, and it was the dual-plane placement of the valves that was the key to its performance. The new "big-block" was also used by Chevrolet and GMC trucks. Production of this generation of engines ended in 1976.
The Rat Motor, as it was nicknamed (as opposed to the small-block "mouse" motor), was slightly heavier than the outgoing 409, with a dry weight of about 685 lb (310.7 kg), but had a stronger, more durable block. This engine was officially known as the "Turbo-Jet V8" from 1965-74.
396
The 396 in³ (6.5 L) V8 was introduced in the 1965 Corvette as the L78 option. It had larger bore and stroke at 4.094 in by 3.76 in (104 mm by 96 mm) than any previous small-block and produced an amazing 425 hp (317 kW) and 415 ft·lbf (563 N·m).
- 1965 Chevrolet Corvette
- 1967-1969 Chevrolet Camaro
402
The 402 was a 396 bored out by .030 in (0.8 mm) introduced in 1970. It was marketed as a "396" in the Chevelle line and as a "400" in the full-size line.
427
The huge 427 in³ (7 L) V8 was introduced in 1966 on the Corvette. Bore was up to 4.25 in, and the power ratings were said to be conservative. The hydraulic-lifter L30 (L36 in 1968) option was rated at 390 hp (291 kW) and 460 ft·lbf (624 N·m), while the solid-lifter L72 pushed out 425 hp (317 kW) and 460 ft·lbf (624 N·m). The 1967 L89 (1968 L71) increased this to 435 hp (324 kW) and 460 ft·lbf (624 N·m), while the L88 from the same years produced 560 hp (418 kW).
The 1969 ZL1 is one of the best-remembered big-blocks. Putting out 430 hp (321 kW) and 450 ft·lbf (610 N·m) from a special camshaft and tuned Holley carb in an aluminum intake, it was a $2000 option! But the all-aluminum engine block weighed just 98 lb, less than half the weight of a similar iron block. Just two production Corvettes were made with this option, making it one of the rarest.
The 427 was also used in GM full-size trucks and available in full sized cars.
- 1966-1969 Chevrolet Corvette
454
The big-block was expanded again for 1970 to 454 in³ (7.4 L) with a 4.251 in (108 mm) bore and 4 in (102 mm) stroke. The 1970 Corvette LS5 engine produced 390 hp (291 kW) and 500 ft·lbf (678 N·m). There was a one-off LS7 which was tuned for performance, with 465 hp (347 kW) and "just" 490 ft·lbf (664 N·m). But included was the king of muscle car engines, the LS6 454. This engine produced 450 hp (336 kW), but replacing the headers could bring it up to 500 hp (373 kW).
Power began falling off after 1970, with the 1971 LS5 producing 365 hp (272 kW) and 465 ft·lbf (630 N·m), and the new LS6 option coming in at 425 hp (317 kW) and 475 ft·lbf (644 N·m). Only the LS5 remained in 1972, now at just 270 hp (201 kW) and 390 ft·lbf (529 N·m). The 1973 LS4 was at 275 hp (205 kW) and 390 ft·lbf (529 N·m), with 5 hp (4 kW) and 10 ft·lbf (14 N·m) gone the next year. 1974 was the last year of the 454 in the Corvette.
GM continued to use the 7.4 L 454 in their truck line, introducing a new Vortec 7400 version in 1996.
- 1970-1974 Chevrolet Corvette
8100
A substantially-modified version of the 454 is sold today as the Vortec 8100.
External links
References
See also
From the 1950s through the 1970s, each GM division had its own V8 engine family. Many were shared among other divisions, but each design is most-closely associated with its own division:
- Buick V8 engine
- Cadillac V8 engine
- Chevrolet Small-Block engine
- Oldsmobile V8 engine
- Pontiac V8 engine
GM later standardized on the later generations of the Chevrolet design:
- GM LT engine — Generation II small-block
- GM LS engine — Generation III/IV small-block
- List of GM engines