They also both use an aluminum block and L92/LS3 cylinder heads. While both the LS3 and LSA make use of higher-flow rectangular port heads, compared to cathedral port heads found on earlier Gen ...
A Step-By-Step Guide Both the LS3 and L99 were built on the fourth-generation GM small block architecture. Both engines are 6.2-liter pushrod V8s that use Gen IV rectangular port cylinder heads.