The 1969 ZL-1 Corvette came equipped with an entirely new big-block engine option that produced more horsepower than any Corvette that had come before it. Any Corvette, when ordered with RPO ZL1, came fitted with an all-aluminum 427 C.I. engine that featured a dry-sump oil system and which weight approximately 100 pounds less than the L88 engine. The ZL1 was a mid-year release for the 1969 Corvette and was actually developed to replace the legendary L88. In addition to the all-aluminum block, the engine featured stouter connecting rods and open-chamber heads.
The ZL-1’s ultra-high-performance engine was developed by Chevrolet in cooperation with McLaren for use in the SCCA’s “Canadian-American Challenge Cup Series” racing. While the engine was officially rated at 430 BHP (the same rating as the L88 engine), the actual engine output of this 427CI engine was between 560 and 585 brake horsepower. It was, simply put, a “racing mill let loose on the street.”
The evolution of the ZL-1 Corvette is an interesting story and a significant milestone in the development of the Corvette as both a high-performance street vehicle and a race car. Although the car never saw much (if any) use as a conventional road-driven Corvette, its creation by GM skirted violating the Automobile Manufacturers Association’s ban on the production of factory-built race cars – a ban that Chevrolet had openly participated in since 1957.