Current Lead Times: In Stock Engines Ship Same or Next Day - Out of Stock: 1-3 Weeks on Most Long Block Engines; 3-5 Days on Heads – *call us for more exact lead times for your specific build
The 6.6L LLY Duramax (2004.5–2006) uses cast aluminum cylinder heads. These heads improve airflow and cooling compared to the earlier LB7. Each head has 32 valves—four per cylinder—and mounts the injectors externally for easier access.
Duramax Cylinder Heads – LLY heads flow exhaust better and have stronger valves. But they can crack or warp under high heat or heavy tuning without upgrades. Performance or remanufactured heads often come with hardened seats, new valve guides, and a resurfaced deck for a better seal.
With the right care or upgrades, LLY heads handle more power, run cleaner, and stay reliable—key for towing and tuned setups.
