One Horsepower Per Square Inch
For a long time, one horsepower per cubic inch (of displacement) was the unobtainable goal. A milestone to be pondered: "Wouldn't it be cool to get a horse per inch?" Today, reaching that level is a fairly simple task (although few production cars make it there). With simple bolt-ons from the performance aftermarket, enthusiasts can achieve well in excess of one horse per cubic inch. Super Chevy magazine has built engines that churn out horsepower three times the displacement numbers.
Chevrolet first hit the one-horsepower-per-cubic-inch level in 1957. The 283 small-block was fitted with Rochester mechanical fuel injection (called "Ramjet injection") and churned out an impressive 283 ponies (a number that grew to 290 the following year). Unfortunately, though, Chrysler beat Chevy to the punch by making a whopping 355 horsepower with its 354 cubic-inch Hemi a year before.
Many of the higher-horsepower engines were actually power packages added to the base engine. Engineers knew that the standard-equipment engines benefited greatly from a little better breathing. The answer was to offer special packages that featured bigger carburetors (or multiple carbs, or fuel injection). The dual-quad carburetor setup (also immortalized in the Beach Boys song "409") was part of a power package designed to beat the competition in the horsepower game. At one time there were 158 different versions of the small-block being produced by Chevrolet-that's a lot of different ways to get power.
Small-Block Milestones
An abridged history of the small-block (by model year):
1955: 265-cid V-8 debuts in the all-new '55 Chevrolet.
1956: Optional four-barrel carburetors available
1957: 283-cid V-8 introduced; Rochester mechanical fuel injection and Duntov cam debut.
Fuel-injected small-block capable of one horsepower per square inch.
1962: 327-cid V-8 introduced.
1964: 327 small-block hits 375 horsepower with Rochester fuel injection; Holley four-barrel introduced on small-block V-8.
1965: In keeping with the power craze, Chevy introduced the Turbo-Jet 396 with the famous "porcupine" heads, so called because each valve was angled toward its port to give optimum gas flow.
1967: 302-cid, 350ci V-8s introduced.
1967: 307-cid V-8 introduced.
1968: Chevrolet incorporated new exhaust emissions control systems on all '68 engines.
1970: 400-cid small-block V-8 introduced; 350ci/370hp LT1 debuts in Corvette and Camaro Z28.
1971: Switch to unleaded gas and new "net" ratings cause dramatic drop in horsepower ratings.
1975: 262-cid V-8 introduced.
1976: 305-cid V-8 introduced.
1979: 267-cid V-8 introduced.
1982: Cross-fire electronic fuel injection introduced; third-generation Camaro paces Indy 500 with aluminum, 350-cid small-block V-8.
1985: Tuned Port Injection introduced.
1986: Production aluminum cylinder heads introduced midyear on Corvette.
1987: Hydraulic roller lifters introduced.
1989: Chevrolet Raceshop develops high-performance H.O. 350 crate motor.
1992: Second-generation LT1 introduced. The first major facelift for the small-block, the new LT1 was shorter and lower to fit under the hood of sleeker-designed '90s vehicles.
Advanced technology significantly improved horsepower over the previous version to an impressive 300 hp. Amazingly, this new power level was accomplished with virtually no loss in fuel economy or increase in emissions.
1994: 4300 (4.3-liter) small-block introduced.
1996: High Output LT4 (330 horsepower), 5000 series and 5700 series Vortec V-8s introduced.
1997: All-aluminum LS1 small-block introduced on C5 Corvette.
1998: Cast-block, aluminum-head LS1 available on Camaro.
1999: Versions of the LS1 labeled the "Vortec" series available on trucks. Six-liter small-block available on 3/4-ton trucks.
2001: LS6, a derivative of the LS1, offered on Corvettes. The engine produces 375 horsepower but is not a big-block like the previous engines designated as LS6.