Shop Cylinder Heads for your 2011-2016 Chevy/GMC 6.6L LML Duramax. Overheating caused by coolant loss or restricted coolant flow and head gasket failure is one of the most common causes of damaged to cylinder heads. If a cylinder head gets too hot it can warp or crack and require expensive machine work or complete replacement. When the metal is heated past normal operating temperatures, it expands past its limits. As it cools, the head often will not return to its original shape or size, instead settling into a more distorted or bent form. In extreme cases of overheating, the cylinder head can even crack and typically needs to be replaced. Fire Rings or O-Rings are offered for mild to high performance engine builds. A cylinder head with a fire ring has a small groove machined around each combustion chamber. A metal ring or hoop is then inserted into it. The ring creates an additional seal that contacts the outer edge of the fire ring in the head gasket. This helps provide a better seal around the combustion chamber. A cylinder head with a machined fire ring ensures greater reliability under extreme stress. This is especially ideal for higher horsepower diesel applications. Find everything you need for your vehicle whether you are searching for factory OE-replacements or performance aftermarket cylinder heads. Both remanufactured heads and brand-new castings are available in either cast-iron or aluminum construction. Offered as bare heads or complete with the valvetrain installed. These fully loaded heads are ready to bolt-on right out of the box and include upgraded valves, seals, retainers, locks, valve springs, as well as hardened seats and guides. High-performance heads are designed to increase flow for more horsepower and torque. Other benefits can include improved cooling and even a weight reduction compared to the stock heads. Shop all the top brands including ProMaxx Performance, Industrial Injection, Edelbrock, Diamond Advantage By Navistar, Ford, Powerstroke Products, Fleece Performance, and more!