19433498 - Chevrolet Performance CNC LS9 Cylinder Head (w/LS3 Valves)

All-New LS9 CNC-Ported Heads Take LS Performance to the Next Level!

Exceptional airflow characteristics are what give the LS engine family its tremendous performance capability, enabling power levels for street engines that were virtually unattainable in previous-generation Small-Block engines. Chevrolet Performance's all-new LS9 CNC-ported cylinder head assembly - P/N 19328743 - represents a new benchmark in factory-engineering high performance, with the strength and durability of the production LS9 cylinder head casting and the airflow enhancements of precision CNC porting. The result is a head that flows about 10 percent more than the production casting, while delivering the greater strength built into the LS9 casting.

The LS9, of course, was the supercharged engine in the C6 Corvette ZR1. To support the higher combustion pressure and temperature that come with forced induction, the heads were produced with a unique Roto-cast method in super-strong A356T6 aluminum alloy. With the Roto-cast method, the mold rotates to more evenly distribute the molten alloy, creating a denser head casting that virtually eliminates porosity. And compared to the similar LS3 head, the LS9 features reinforced webbing and a thicker deck for greater rigidity and minimal distortion. The A356T6 alloy also manages the higher heat of a forced engine more effectively.

In short, Chevrolet Performance's LS9 CNC-ported head assembly is the ultimate production-based solution for supercharged and turbocharged combinations. Each comes fully assembled with production, lightweight hollow stem intake valves and solid stem exhaust valves, as well as strong beehive-type valve springs that can handle up to .570" lift. Importantly, they can be installed on any LS engine with at least a 4.000" bore using standard 11mm head bolts.

LS9 CNC-Ported Head Features:

• Special A356T6 aluminum Roto-cast head casting for greater strength. The mold is rotated during production to create a more solid casting that virtually eliminates porosity
• Reinforced webbing and thicker deck (for minimal distortion) makes it an excellent choice for supercharged and turbocharged engine combinations
• CNC-ported for approximately 10 percent greater airflow (intake side) than the regular-production cylinder head (similar to LS3 CNC-ported head P/N 88958758)
• As-cast 66.5cc combustion chamber volume
• Fully assembled with production LS3 2.165" (55mm) hollow intake valves and solid 1.590" (40mm) exhaust valves; and beehive-type valve springs
• Valve springs rated for .570-inch" max lift
• Can be used on LS engines with at least a 4.000" bore using standard 11mm head bolts in place of the LS9's 12mm head bolts