Chevrolet officially rated the 1967 Corvette L88 at 430 horsepower — a number almost nobody believes, with real output reputed to be closer to 560 or even 600. Only 20 of the 22,940 Corvettes built that year carried the option, which required deleting the heater, radio, and air conditioning just to qualify. A Sunray DX-entered L88 went on to win the 12 Hours of Sebring outright that same year. Read on for how Chevrolet built the most powerful — and most deliberately hidden — engine it ever put under a Corvette hood.