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 Gen IV LS9 is a supercharged engine, based on the LS3; the LS7 block was not used due to the higher cylinder pressures created by the supercharger requiring the thicker cylinder walls of the LS3. Cylinder dimensions are now bore and stroke of . It is equipped with an Eaton four-lobe Roots type supercharger and has a compression ratio of 9.1:1. Power output is rated @ 6500 rpm and @ 3800 rpm of torque. Note: GM previously used the LS9 RPO code on 1969 and later Chevrolet trucks (both 2WD and 4WD) including Blazers, Jimmys, Suburbans, as well as car carriers. The original LS9 was a V8, developing and of torque.