The 1971 Chevrolet Corvette ZR-2 featured GM’s 454 cubic-inch LS6, which sported a Holley carburetor and purpose-specific aluminum intake, much like the LT-1. The LS6 also shared a common 9.0:1 compression ratio with its ZR-1 counterpart. Official documentation specifies the LS6’s output at 425 HP, though true values of this nature are often disputed. Many feel that the LS6’s HP was significantly downplayed, as several reports point to an actual output well above 500 HP.
Today, the 1971 ZR-2 is known collectively as GM’s final foray into the upper echelons of hard-line performance, before the implementation of endless red tape on behalf of regulatory practices. While the Corvette has since returned to, and surpassed, this long-standing benchmark, a lengthy period of performance decline presided over the iconic American sports car in the years following the ZR-1 and ZR-2’s reign.