FIGHTING HEAT AND AIR RESTRICTIONS WITH PPE’S LLY MOUTHPIECE ON AN ‘04.5 CHEVROLET
When it comes to GM pickups, there isn’t a better engine option than the 6.6L Duramax diesel. Introduced in ‘01, the Duramax was practically a Formula One engine in its time, with revolutionary aluminum heads and common-rail injection. There were a few shortcomings however, and it’s those issues that we’ll be addressing in our testbed 120,000-mile ‘04.5 Cheverolet 2500 HD.
New for the 2004 half-year was a VGT turbo, which flowed more than the previous LB7 turbo, and also had variable vanes, which allowed for the new LLY engine to spool up much quicker than the previous LB7. Just like many changes however, there were shortcomings to this new design. Thankfully though, they’re pretty easy to fix!
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.)
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.
The intake mouthpiece was a fairly easy install, and it took our shop less than an hour to complete the job. With the LLY’s being great trucks (other than their cooling issues) we could now rest easy that the engine was running a few degrees cooler (with more power capability), and at least one of the truck’s cooling issues could be crossed off the list.