Big-block
From Free net encyclopedia
Image:12498793.gifA big-block engine is a North American V8 in a family of engines which generally have greater than 5.9 L (360 cubic inches) of displacement; factory engine sizes reached a peak of 8.2 L (500 cubic inches) in Cadillac's 1970s range. Since then manufacturers have responded to the need for superior engines, as well as the need to replace surviving worn-out, decades-old big-block racing engines which have been rebuilt too many times. In 2002 General Motors released the carbureted Chevrolet 572 crate engine (9.4L), available for installation in most vehicles which have enough room under the hood, both in a 620 hp street version, which runs on premium gasoline, and a 720 hp version, which requires racing fuel. Mopar (Chrysler) recently released the 528 Hemi (8.7L) and 540 (8.8L) crate engines. Both of these incorporate modern hardened metals and are able to run on unleaded gasoline.
Smaller V8 engines are known as small-blocks; some members of small-block engine families may exceed 6 L, blurring the distinction somewhat. The distinction came about in the early 1960s when the large full-size cars needed a bigger V8 than the smaller mid-size and compact cars. Before that, manufacturers normally had only one V8 engine line.
The term is normally used only for engines from the "Big Three" (Ford Motor Company, General Motors, and Chrysler Corporation) since the other companies did not keep two V8 engine size families.
Big-block V8s were most commonly used in full-size and luxury cars, rather than performance vehicles. Thus, they were commonly tuned and built for smoothness, low-end torque to get heavy cars rolling and effortless cruising. Many big-block engines were less technically sophisticated than their small-block counterparts, and their power-to-weight ratios were often lower. Today of course big-block engines are used in racing.
They did see performance applications, however. Performance-tuned big-blocks were used in NASCAR racing, and homologation requirements saw these engines sold for road use. NASCAR's 7 L engine size limit explains why many high-performance big blocks are of this size; Chevrolet's 427, Ford's 427, Chrysler's 426 Hemi. In the mid to late 1960s, the explosion of the muscle car market saw performance big-blocks fitted to intermediate-size cars. Some used derivatives of the racing engines, but in addition performance versions of former luxury motors were produced.
After the 1973 oil crisis, the days of the big-block in passenger cars were numbered. By the end of the 1970s, they were no longer to be found. However, these engines remained in use in pickup trucks and other non-car uses. Currently, only GM offers big-block V8s in its trucks; Ford and Chrysler essentially replaced their big-blocks with stretched V10 versions of their small-block engines in the early to mid 1990s.