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.
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.