Wiki source for Head
Head
In an internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency and compression ratio of the engine.
Contents
1 Gasket
1.1 Cometic
1.2 Fel-Pro
1.3 Copper
1.4 OEM
2 Studs/Bolts
2.1 ARP
2.2 OEM
3 Porting
3.1 J-Body Performance
3.2 DIY
Gasket
A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine. Its purpose is to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders; as such, it is the most critical sealing application in any engine, and as part of the combustion chamber, it shares the same strength requirements as other combustion chamber components.
Cometic
Cometic Head Gaskets are specially built for forced induction, high compression, or nitrous applications. It features a thicker shim around the cylinder walls to increase seal. The outer layers of the gasket are embossed and coated on both sides with a flouroelastomer rubber based material (Viton) designed to meet the demands of a variety of harsh sealing environments, load conditions and surface finishes. Available at TurboTechRacing. The width you order depends on what you want to do to your compression ratio or if you want to compensate for a shaved head surface. Thicker gasket, lower compression, thinner gasket, higher compression.
Fel-Pro
The gasket made by Fel-Pro is typically sufficient for applications up to around 13 PSI of boost. (Generally, those who run 15 PSI on the Fel-Pro have them blow around that range). Excellent stock replacement, low priced. Available at your local parts store such as AutoZone, Advance Auto Parts, etc.
Copper
These gaskets tend to leak often and are not suggested for a street driven vehicle. They require constant retorquing of the head bolts to maintain proper tension because copper is so soft. Every heat/cool cycle of the engine takes away a little tension as the head and block expand and squeeze harder on the gasket, then release as they cool. SCE makes the Titan head gasket for the LD9, however it has been difficult to locate lately for purchase.
OEM
The head gasket offered straight from GM is a stock replacement with stock quality. Available at GMPartsDirect or your local dealership for a bit of a high price.
Studs/Bolts
Obtaining the optimum cylinder head-to-block sealing is especially critical in small displacement engines employing high compression pistons or power adders like turbochargers, nitrous oxide and superchargers.
ARP
ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is precisely heat-treated to 200,000 psi. Following heattreat, each stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. Available at CarCustoms.
OEM
The stock head bolts are usually sufficient for most applications. If you're looking to obtain the maximum power from your engine, however, you should definitely utilize ARP's head studs. Not only does it make aligning the gasket and head far easier, but they are stronger and do not require any regular re-torquing like the stock bolts do. If you rebuild the engine, you MUST use new head bolts (unless you're using studs already).
Porting
Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the gas flow. Cylinder heads, as manufactured, are usually suboptimal due to design and manufacturing constraints. Porting the heads provides the finely detailed attention required to bring the engine to the highest level of efficiency.
J-Body Performance
JBP sells a complete 2.4L race head kit. Now a sought after item is our full 2.4L race head kit. This kit comes with everything you require for your valvetrain and cylinder head build. Everything is top of the line. As you'd come to expect with JBP, nothing has been spared. 5 angle valve job, stainless steel valves, HD custom valve springs, all new seals, with computerized flow bench data sheet. Our head kit also includes pistons (specifically designed by JBP, produced by our affiliate WiseCc pistons to accomodate a N/A, Nitrous or forced induction application. To further push the envelope, the widest port matching available with a stock gasket or even further with our custom gasket. We've cut down the valve stems and polished to a mirror smooth finish. Gains are ~ 33WHP.
DIY
For cost savings and personal precision, one can port the head themselves using the Standard Abrasive small engine kit, which includes basically all you need to remove material and polish. Information on porting the LD9 head can be found in this thread from the J-Body Organization. DIY port and polish is something that must be done with care and precision, and by someone who knows what they're doing and where and what to modify. Many websites give tips on these items, but the link above has the essentials for this specific engine cylinder head.
In an internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency and compression ratio of the engine.
Contents
1 Gasket
1.1 Cometic
1.2 Fel-Pro
1.3 Copper
1.4 OEM
2 Studs/Bolts
2.1 ARP
2.2 OEM
3 Porting
3.1 J-Body Performance
3.2 DIY
Gasket
A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine. Its purpose is to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders; as such, it is the most critical sealing application in any engine, and as part of the combustion chamber, it shares the same strength requirements as other combustion chamber components.
Cometic
Cometic Head Gaskets are specially built for forced induction, high compression, or nitrous applications. It features a thicker shim around the cylinder walls to increase seal. The outer layers of the gasket are embossed and coated on both sides with a flouroelastomer rubber based material (Viton) designed to meet the demands of a variety of harsh sealing environments, load conditions and surface finishes. Available at TurboTechRacing. The width you order depends on what you want to do to your compression ratio or if you want to compensate for a shaved head surface. Thicker gasket, lower compression, thinner gasket, higher compression.
Fel-Pro
The gasket made by Fel-Pro is typically sufficient for applications up to around 13 PSI of boost. (Generally, those who run 15 PSI on the Fel-Pro have them blow around that range). Excellent stock replacement, low priced. Available at your local parts store such as AutoZone, Advance Auto Parts, etc.
Copper
These gaskets tend to leak often and are not suggested for a street driven vehicle. They require constant retorquing of the head bolts to maintain proper tension because copper is so soft. Every heat/cool cycle of the engine takes away a little tension as the head and block expand and squeeze harder on the gasket, then release as they cool. SCE makes the Titan head gasket for the LD9, however it has been difficult to locate lately for purchase.
OEM
The head gasket offered straight from GM is a stock replacement with stock quality. Available at GMPartsDirect or your local dealership for a bit of a high price.
Studs/Bolts
Obtaining the optimum cylinder head-to-block sealing is especially critical in small displacement engines employing high compression pistons or power adders like turbochargers, nitrous oxide and superchargers.
ARP
ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is precisely heat-treated to 200,000 psi. Following heattreat, each stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. Available at CarCustoms.
OEM
The stock head bolts are usually sufficient for most applications. If you're looking to obtain the maximum power from your engine, however, you should definitely utilize ARP's head studs. Not only does it make aligning the gasket and head far easier, but they are stronger and do not require any regular re-torquing like the stock bolts do. If you rebuild the engine, you MUST use new head bolts (unless you're using studs already).
Porting
Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the gas flow. Cylinder heads, as manufactured, are usually suboptimal due to design and manufacturing constraints. Porting the heads provides the finely detailed attention required to bring the engine to the highest level of efficiency.
J-Body Performance
JBP sells a complete 2.4L race head kit. Now a sought after item is our full 2.4L race head kit. This kit comes with everything you require for your valvetrain and cylinder head build. Everything is top of the line. As you'd come to expect with JBP, nothing has been spared. 5 angle valve job, stainless steel valves, HD custom valve springs, all new seals, with computerized flow bench data sheet. Our head kit also includes pistons (specifically designed by JBP, produced by our affiliate WiseCc pistons to accomodate a N/A, Nitrous or forced induction application. To further push the envelope, the widest port matching available with a stock gasket or even further with our custom gasket. We've cut down the valve stems and polished to a mirror smooth finish. Gains are ~ 33WHP.
DIY
For cost savings and personal precision, one can port the head themselves using the Standard Abrasive small engine kit, which includes basically all you need to remove material and polish. Information on porting the LD9 head can be found in this thread from the J-Body Organization. DIY port and polish is something that must be done with care and precision, and by someone who knows what they're doing and where and what to modify. Many websites give tips on these items, but the link above has the essentials for this specific engine cylinder head.
