Chrysler A engine
The Chrysler A engine is a small-block V8 gasoline engine built by Chrysler with polyspherical combustion chambers. It was produced from 1956 until 1967, when it was replaced by the wedge-head LA engine. It is not related to the hemispherical-head Hemi engine of the same era.
LS based GM small-block engine
The LT4 engine builds on the design strengths of the previous LS9 supercharged engine used in the sixth-generation Corvette ZR1 and leverages the technologies introduced on the seventh-generation Corvette Stingray, including direct injection, cylinder deactivation and continuously variable valve timing, to take Corvette performance to an all-new level. The LT4 engine is based on the same Gen 5 small block foundation as the Corvette Stingray’s LT1 6.2 L naturally aspirated engine, incorporating several unique features designed to support its higher output and the greater cylinder pressures created by forced induction, including: Rotocast A356T6 aluminum cylinder heads that are stronger and handle heat better than conventional aluminum heads, lightweight titanium intake valves, forged powder metal steel connecting rods which are highly machined to an optimized geometry for increased strength while eliminating unnecessary reciprocating mass, 10.0:1 compression ratio, high for a forced-induction engine, enhances performance and efficiency and is enabled by direct injection, forged aluminum pistons with unique, stronger structure to ensure strength under high cylinder pressures, stainless steel exhaust manifolds for structure at higher temperatures, aluminum balancer for reduced mass, and standard dry-sump oiling system with a dual-pressure-control oil pump. The engine uses a Eaton TVS Supercharger. Although smaller than the previous supercharger used on the sixth-gen ZR1, it spins to 5000 RPM faster thus generating boost quicker while making only slightly less total boost than the LS9 engine.