'Big blocks' powered big, faster Chevys

Cars and trucks got bigger and heavier in the 1950s. The advent of turnpikes and interstate highways meant faster travel. Those factors combined to create showroom demand for more powerful engines.

Chevrolet engineers responded. Increasing engine displacement was the easy route to more power, and the new V-8s came to be known as "big blocks."

Chevrolet's first big block appeared in 1958. Initially developed for trucks, the 348-cubic-inch (5.7-liter) iron block and iron head engine weighed a hefty 665 pounds. The Workmaster V-8 fitted with a two-barrel carburetor produced 230 hp, a 10 percent bump in power over a 283-cubic-inch small block V-8.

Today, the Chevrolet Corvette's all-aluminum 376-cubic-inch (6.2-liter) LS3 V-8 weighs about 415 pounds and produces 430 hp.

Product planners quickly realized the marketing appeal of more powerful V-8s for full-sized Chevys. Several horsepower variations were offered for 1958: the Turbo-Thrust with a 4-barrel carburetor and 250 hp; the Super Turbo-Thrust with three 2-barrel carburetors and 280 hp; and the Super Turbo-Thrust "Special" with triple carburetors and 315 hp.

Despite the names, none of these engines used turbochargers.

Chevrolet did not track engine installations until later in the 1960s, so it is unknown how many vehicles had big blocks. The engine was popular enough to remain in production and to be improved.

Heralded in song by the Beach Boys, the first evolution of Chevy's big block included the 1961 409-cubic-inch V-8. An increase in bore and stroke helped the mighty 409 to produce as much as 425 hp by 1963.

The 427-cubic-inch, 430-hp version stands as the original big block's zenith. Only 50 are thought to have been built, with most likely sold to drag racers.

The Mark IV engine superseded the original big block in 1965, offering several displacements including models of 366, 396, 402, 427 and 454 cubic inches. The new engine generated more power, up to 435 hp, which gave extra potency to Corvettes and Camaros.

When insurance costs and emissions regulations brought an end to the muscle car era and the first Arab oil embargo in the early 1970s made fuel economy a higher priority, the big block faded away. The 1974 Corvette was the last Chevrolet car available with a 454-cubic-inch V-8. The 454 was used in some Chevy trucks and survived as the Vortec 7400 until 1996.

In the high-performance Corvette Z06, Chevy still offers 427 cubic inches of displacement, but this engine is a bored and stroked small block. Modern technology makes physically big blocks unnecessary because more power can be produced per cubic inch than in the 1950s through 1970s.

The Chevy big block lives on in the aftermarket crate engines, derived from the Mark IV, that are available from GM Performance Parts. The largest displacement is 572 cubic inches.