Gen IV Small Block Engines Feature Refinements and Advanced Tech

27.04.2010

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GM’s $890 million investment to produce cleaner and more efficient next-generation small block engines builds on a heritage of innovation and technology – and nearly 100 million engines produced. 

The current fourth-generation small block engine powers the Chevrolet Corvette, Cadillac CTS-V and the GMC Yukon as well as many other models.

Gen IV engines are characterized by refinements and advanced technology such as variable valve timing and Active Fuel Management. Variable valve timing enables improved torque, fuel economy and emissions. Active Fuel Management disables the combustion process of half the engine’s cylinders in certain driving conditions, enabling fuel savings of up to 5 percent in trucks and 12 percent in cars.

Many Gen IV variants can run on gasoline, E85 ethanol or any combination of the two.

Contemporary demands for efficiency and performance refinements were the very demands that pushed the original small-block’s development 55 years ago. Although a new engine was on the drawing table when Chief Engineer Ed Cole transferred from Cadillac to Chevrolet, he soon dismissed the original design and challenged his engineers to develop a more compact engine that would be easier to manufacture.

In the early ’90s, the Gen II small-block was introduced in cars including the Corvette. Known as the LT1 and, later, the LT4, the Gen II featured new, low-friction internal components and reverse-flow cooling to enable the efficient and great performing small-blocks. Some Gen II features, including the low-profile, high-flow intake manifold, previewed technology that would be incorporated into the all-new Gen III.

The Gen III was introduced as the LS1 5.7-liter engine in the 1997 Corvette, while Vortec versions of the Gen III for trucks were introduced in 1999, with displacements ranging from 4.8 liters to 6.0 liters. The Gen III engine benefited from new technology, including replicated cylinder head ports, six-bolt mains, gerotor oil pump and composite intake manifold, but its design drew upon more than 40 years of research and continuous improvements from the Gen I and Gen II small-blocks.