Chevrolet 454 Big-Block engine

Chevrolet 454 Big-Block engine

Update Himmel

St.Martin,F.W.I.
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 Corvette LS5 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. Indeed, the AHRA ASA Class record holding Chevelle LS6 for the 1970 season posted a record setting trap speed of 106.76 mph (171.81 km/h) "1970 ASA LS6 454 Records", which suggests something on the order of 370 "as installed" (SAE Net) HP for a 3,900 pounds (1,800 kg) car and driver combination.

A 465 hp (347 kW) and 490 lb·ft (660 N·m) version of the 454, dubbed LS7 was also designed but never went to production. However, a handful of LS7 intake manifolds were produced and sold by a few Chevy dealers as performance parts. The LS7 was later offered as a crate engine from GM and advertised at 500 hp (370 kW).

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 though the Chevelle offered it in the first 1/2 of the 1975 model year. It was also available in the full size Impala/Caprice until model year 1976.

GM continued to use the 7.4 L (454 cu in) in their truck line, introducing a new Vortec 7400 version in 1996. GM also introduced the 7.4 L 454 EFI in 1990 (known as the GEN V; the previous generation was known as the Mark IV produced between 1965-90; the GEN prefix was used since Ford Motor Company owns the Mark V naming rights since it was used on a Lincoln automobile between 1977-79), which was electronically fuel injected giving more power and torque. The 454 EFI version was rated from 230 hp (170 kW) to 255 hp (190 kW) and from 385 lb·ft (522 N·m) to 405 lb·ft (549 N·m) of torque. The 7.4 L 454 EFI was found on GM 3500 trucks throughout the early 1990s until replaced with the Vortec 7400 (GEN VI) in 1996.
http://en.wikipedia.org/wiki/Chevrolet_Big-Block_engine