Is an LS6 intake swap a good idea on a truck 5.3/6.0?
It can work, but it's not the best factory option for a truck.
Among factory cathedral-port intakes, back-to-back testing puts the TBSS (TrailBlazer SS) intake on top, but it's tall and often won't fit low-hood cars — which is where the LS6 intake comes in. The truck, LS2, LS6 and TBSS intakes all work well; the original LS1 intake is the weak one. An LS3 (rectangle-port) intake on cathedral heads with adapters is a poor choice.
On a hot-rodded LS1 the LS6 intake has been a quick upgrade worth 15-plus hp, and it matters most where hood height rules out the TBSS. GM stopped making the LS6 intake; Dorman's replacement tested nearly the same as the original in OnAllCylinders' dyno test. On a truck with hood room, the TBSS intake is the stronger factory choice: +13 hp / +4 lb-ft over the truck intake with the first cam in Holdener's test.
On a truck 5.3 or 6.0, we don't recommend the LS6 intake swap for most builds. The truck intake makes as much or more torque, and in the builds we've seen there's no difference below 4500 rpm, with gains of only 1-2 mph and about a hundredth at the track after a retune; on smaller trucks the swap has even slowed them down. It also means changing to an L92 water pump, relocating the idler pulley and trimming the alternator/PS bracket because the throttle body hits the belt drive. If you have an early 5.3, the TBSS intake is about the only stock intake worth upgrading to.
Check this first:
- Whether your truck actually spends time above 4500 rpm
- Water pump, idler and bracket clearance for the throttle body
- Injector/rail fitment (spacers may be needed)
Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead tuner (20 years of LS tuning). Every combination is different, so use at your own risk and check our safe tuning limits before any wide-open pass.
Further reading
- www.gm-trucks.com/forums/topic/67309-for-all-those-considering-ls6-int
- www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/truc
Related questions
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- 6.0L LS Truck Engine Tech: A Truck vs. TrailBlazer SS (TBSS) Intake Manifold Comparison Test — OnAllCylinders (Summit Racing)
- Quick Test: Dyno Testing Dorman's LS6 Intake Manifold — OnAllCylinders (Summit Racing)