Chevrolet Corvette ZL1
As the horsepower war reached a crescendo in the late 1960’s, Chevrolet had a very deep war chest. Their Mark IV 396ci big block had grown to 427ci in 1966. While it was powerful, the iron block/iron head combination was extremely heavy. In an effort to combat excess weight, GM had developed aluminum cylinder heads as part of the RPO L88 racing package and was working on an aluminum MK IV block to go along with them. A low-volume production version became available in 1969 as RPO ZL1, though only three were installed in Corvettes. There were 69 Camaros produced with the engine and another 154 were sold as crate motors. A ZL1 big block weighed less than an iron small block, and while rated at 430 hp; they actually developed about 525 hp the way they left Tonawanda. Out in the real world, they made over 600 hp when fitted with tubular headers. Though powerful nearly beyond belief, Car & Driver was only able to bumble its way to a quarter mile pass of 13.8 at 105 mph in a Corvette ZL-1. Put in the hands of a more experienced driver, however, it was a solid 11-second car.