Chevy Small Block History - The Best Things Come In Small Packages

More Than 50 Years of Small-Block Chevys

Bob Mehlhoff May 1, 2006 0 Comment(s)

Step By Step

Here's a look inside one of today's high-performance small-blocks with roller camshafts, high-compression pistons, a custom-stroke crankshaft, and very high-flowing cylinder heads.

This Corvette Gen III LS1 engine has 346 ci, 10:1 compression, and an aluminum block and heads. Although it looks entirely different than the first 265 small-block, this engine is still designed with the 4.40-inch bore spacing.

The new LS6 engines (for '01) produced 385 hp and 405 the following year ('02). At the time these engines boasted "performance never before seen with a small-block." Today, the small-block's advancements with 505 hp from the LS7 overshadow the LS6. Technology is always moving ahead at Chevrolet.

As noted, the ultimate factory small-block Chevy (as of '06) is the LS7 with 427 ci, 505 hp, forged titanium connecting rods, and CNC-ported LS7-specific pattern cylinder heads. This all-aluminum engine (generally designed for the '06 Z06 Corvette) is sporadically available as a crate engine (sold through GM parts centers) under PN 17802397. Installed in a '06 Z06 Corvette, the engine will propel the car 0 to 60 mph in 3.5 seconds (all in First gear), blast through the quarter-mile in 11.5 seconds, and if there is enough room to continue up, you can expect top speeds of 195 mph. Do radar detectors work on cars like this?

The Gen III small-block was introduced as the LS1 5.7L (346ci) engine in the '97 Corvette, while Vortec versions of the Gen III for trucks were introduced in '99. This engine is configured in four displacements, 293 (4.8L), 325 (5.3L), 346 (5.7L), and 364 (6.0L). All 5.7L LS1 engines are aluminum blocks, while most other Gen III displace-ments (typically used in trucks) are cast iron. The best known is the 346, or 5.7L, and may be why many hot-rodders call all Gen III engines LS1.

The Gen III engine benefited from completely new technology (designed from a clean sheet of paper) and production methods, but even still its design drew upon more than 40 years of research and continuous improvements from the Gen I and Gen II small-blocks. Ongoing improvements on the Gen III project also supported the development of new efficiencies and power increases in the Gen IV. In many of today's modified musclecars, the Gen III/LS1 is a very popular engine swap. At the foundation is a deep-skirt, six-bolt main block that definitely has the structure to provide for a strong and dependable engine. What's especially exciting inside a Gen III are the good-flowing cylinder heads with replicated ports. Inside you'll find 2.00-inch intake and 1.55-inch exhaust valves. And if you would like to retain a carburetor, there are LS-series four-barrel carburetor manifold kits available at reasonable prices. Other good news is that used engines of this variety are beginning to surface. To help with an LS1 engine installation, lots of aftermarket companies, such as Year One, offer installation kits for musclecars, like early Camaros. GM also sells an installation book (PN 88959384) for an LS1 or LS6 going into an older vehicle.

The New Gen IV
Recently, GM introduced the Gen IV small-block V-8, 50 years after the first small-block appeared. This engine is available in V-8-equipped models of the '05 Chevrolet TrailBlazer EXT, GMC Envoy XL, GMC Envoy XUV, and in the soon-to-be-released '06 Chevrolet Monte Carlo and Impala. The new LS2 and LS7 Z06 engines are part of this engine family.

Some of these engines now offer fuel-saving Displacement on Demand (DOD) technology, and there are plans to have this feature on all Gen IV engines. This fuel-economizing feature has the capability of disabling the combustion process of half the engine's cylinders during certain driving conditions, enabling fuel savings of up to 8 percent. The process is instantaneous and virtually imperceptible, and the engine delivers horsepower and torque bands comparable to previous non-DOD small-block engines. We've driven new GM vehicles with this feature and the cylinder transition is seamless. Most recently a 6.0L V-8 version of the Gen IV engine without DOD is available in the Corvette.

Looking Ahead
Beyond the latest power numbers, the significance of the small-block Chevy has been how well GM Powertrain has continued to develop a product to surpass market demands by finding new ways to incorporate the latest technology. Just as in the past, the engine is continually positioned to reign the most hot-rodded engine ever. Something we all look forward to.




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