The factory 78mm LS6 throttle body has long been a bottleneck on performance applications, especially once camshaft and cylinder head changes are made. Unfortunately, the aftermarket solutions that offer larger throttle body openings are typically extremely expensive and often do not offer direct bolt-on fitment, especially with cable operated throttle body applications.
Fortunately, there is now an aftermarket alternative! Dorman has released their 90mm aftermarket LS6/LS2 replacement intake manifold. This intake was designed to be a direct replacement to the factory LS1, LS6, and LS2 intakes and can easily be fitted to any cathedral port LS engine application. Dorman designed their lower plenum around the FAST 78 lower intake mold and fitted a proprietary LS6 style upper plenum with a 90mm throttle opening to their lower casting. The result is an affordable aftermarket solution to the LS6 intake manifold that performs well and is designed to use existing hardware. Independent dyno testing has shown this casting to perform comparably to, or within several HP of, a FAST aftermarket casting.
These castings are designed for use with your OE sensors, fuel rails (both LS1/LS6 and LS2 style), and injectors. A MAP sensor extension may be required and HVAC control vacuum may require a tee if applicable. Your OE throttle cable bracket can be retained with this intake and used in conjunction with a 90-92mm aftermarket cable actuated throttle body.
Note: Modification to your existing steam vent lines or replacement with aftermarket steam vent lines may be required due to the limited distance between the bottom of this intake and the OE valley cover.
Perfect for your restomod or LS swap project, these intakes offer excellent hood clearance at less than 7 inches tall and are a great alternative to truck style intakes (pending front accessory drive clearance). Their lightweight polymer design offers excellent resilience to radiant heat soak, helping to keep your intake air temperatures low. While these perform well out of the box, they respond even better to porting and/or light casting clean-up if you’re looking for maximum horsepower. You absolutely will not find a better value for a brand new aftermarket intake casting that offers out-of-the-box fitment with OE components.
NOTE: This is not a GM casting and is an aftermarket reproduction intake manifold produced by Dorman