The Bad

When the LLY engine was designed, the intake was made to be free-flowing, but the post-turbocharger intake horn was not. In fact, it’s much, much smaller than the turbocharger inlet, which creates a bottleneck, especially at wide open throttle or when towing. Remember that the turbo will still try to force the air into the engine, creating higher boost pressures and hotter air (and therefore higher exhaust gas temperatures and engine operating temperatures.)

The Fix

Since our testbed Duramax-powered Chevy ran a little on the hot side anyways (especially in 90 to 100 degree weather) this opportunity seemed like the perfect time to test Pacific Performance Engineering (PPE’s) LLY turbo inlet upgrade kit. Unlike the factory piece, the PPE unit doesn’t neck down at all, creating a much more free flowing intake path with less restriction to the engine. The undersized factory turbo inlet creates a pressure drop in the intake air supply that feeds the turbo with super heated intake air.This air then enters the intercooler, which absorbs some of the heat and then passes this heat to the radiator that is positioned directly behind the intercooler. The cooling efficiency of the radiator is therefore reduced, leading to higher engine temperatures.


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