LLY cylinder heads have an excellent 4-valve design that promotes high flow and swirl in stock form. Banks' engineers performed extensive flow bench testing to determine which additional modifications would result in maximum intake and exhaust efficiency without compromising the structural integrity of the aluminum cylinder heads.

Flow testing produced data that helped Banks' engineers achieve maximum port flow. Intake port flow was increased by over 30% @.500 lift and exhaust port flow was increased by over 50% @.500 lift. Once optimum port development was established, the ported heads were digitized for programming and machining on 5-axis CNC machining centers.

The twin Honeywells Garrett race turbochargers will generate enormous boost pressure which will require serious measures to seal heads to the block. Garlock Helicoflex low-distortion sealing rings will be tested. Banks-spec custom studs will also replace the stock head bolts.

Custom stainless steel intake and larger-diameter inconel stainless exhaust valves will replace stock intake and exhaust valves. Both valves are now 33mm (stock exhaust valves are 31mm). In addition, custom Manganese bronze self-lubricating valve guides and tungsten carbide alloy valve seats will be used to conduct as much heat away from the surface of the valves as possible. To reduce valvetrain mass, smaller, lighter and shorter lifters were developed to travel in bronze guide bushings pressed into the Duramax blocks. To match the cylinder head flow, a custom intake manifold is being designed and fabricated at Banks.

Duramax Heads and Valvetrain Overview:

• Smaller, lighter and shorter roller lifters

• Banks-designed bronze lifter guide sleeves

• Stainless steel intake and larger (33mm) inconel stainless steel exhaust valves

• Custom valve springs designed by Eibach

• Increased flow on the intake ports by over 30% @ .500 lift

• Increased flow on the exhaust ports by over 50% @ .500 lift