454 V8
The big-block was expanded again for 1970 to 454.2 cubic inches (7.4 L) with a 4.251 in (108.0 mm) bore and 4 in (100 mm) stroke. The 1970 Chevy CorvetteLS5 version of this engine produced 390 hp (291 kW) and 500 lb·ft (680 N·m), and the LS6 engine was rated at 450 hp (340 kW). It has been suggested that the LS6 was substantially underrated and actually produced well over 500 horsepower (370 kW) as delivered from the factory, although there is no empirical evidence to support this claim.
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Power began falling off after 1970, with the 1971 LS5 producing 365 hp (272 kW) and 465 lb·ft (630 N·m), and the LS6 option coming in at 425 hp (317 kW) and 475 lb·ft (644 N·m). Only the LS5 remained in 1972, when SAE net power ratings and the move towards emission compliance resulted in to 270 hp (200 kW) and 390 lb·ft (530 N·m). The 1973 LS4 produced 275 hp (205 kW) and 390 lb·ft (530 N·m), with 5 hp (3.7 kW) and 10 lb·ft (14 N·m) gone the following year. Hardened valve seats helped allow these engines to last much longer than the earlier versions, even without the protection previously provided by lead from fuel. 1974 was the last year of the 454 in the Corvette.
These engines were available in 1970, 1971, 1972, 1973, and 1974.
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