More than 1 hp per cubic inch. Mention that phrase to Chevrolet enthusiasts and you’ll probably hear about early Z/28 engines, fuel-injected 327s, and a few big-blocks. But Chevrolet has a completely new engine that not only delivers that kind of power, but also does it with fuel-efficient performance and unmatched smoothness. The engine is called the Vortec 4200 I6 and was initially created for General Motors’ midsize sport utility vehicles. Chevrolet engineers created a 24-valve, dual overhead cam, all-aluminum straight-six that produces 270 hp from 256 cubic inches, with 90 percent of its torque coming in from 1,600 to 5,600 rpm. Let’s take a closer look at this amazing new engine.