Chevrolet small-block engine
In 1992, GM created a new-generation small-block engine called the "LT1 350", not to be confused with the high-output Generation I LT-1 of the 1970s. It displaced , and was a 2-valve pushrod design. The LT1 used a reverse-flow cooling system which cooled the cylinder heads first, maintaining lower combustion chamber temperatures and allowing the engine to run at a higher compression than its immediate predecessors.
Chevrolet big-block engine
The 1969 ZL1 version of the 427 engine was developed primarily for Can-Am racing, where it was very successful in cars like the McLaren M8B. The ZL1 specifications were nearly identical to the production L88 version of the 427, but featured an all-aluminum cylinder block, in addition to aluminum cylinder heads, The first Corvette RPO ZL1 engine package was built in late Fall 1968 and featured aluminum closed chamber heads, until sometime in 1969, when the Corvette ZL1 engine changed to having open combustion chamber aluminum cylinder heads, as the 1969 L88 had. The ZL1 engine also featured a light weight aluminum water pump, a camshaft that was slightly "hotter" than the L88's, and a specially tuned aluminum intake manifold. Like the L88, the ZL1 required 103 octane (RON) (minimum) fuel, used an unshrouded radiator, and had poor low speed idle qualities - all of which made the two engines largely unsuitable for street use. (102 octane RON [Sunoco 260] represented the highest octane gasoline sold at common retail stations.)