Air is drawn into the two Garrett GT35R turbos through conical K&N filters and ductwork powdercoated red by Maas Brothers powdercoating in Livermore, California. The boosted air is then routed through a custom intercooler and is sprayed with methanol from an Alkycontrol super pump system to reduce the possibility of detonation. The truck's cooling system was also upgraded to reduce detonation by adding Evans Cooling Systems waterless coolant.
The air/alcohol mixture is then fed through an L76 intake and into the cylinders via L92 heads and a custom ground Synergy cam with .620 inches of lift. The L76/L92 combo is what you'd find on an LS3, but for Mark's application they were given a Stage 2 porting job, dual valve springs, and Harland Sharp roller rocker bearings by West Coast Cylinder Heads. Mark has big plans for the engine, so two Bosch 420 fuel pumps were added to keep the 96 lb per hour injectors fed when the throttle is pegged. When Mark finally eases back on the throttle, a Vortech Mondo blow-off valve keeps the turbos from surging.
If you look at the bottom...
If you look at the bottom of the intake tubing, just before the MAF sensor, you can see the fitting for the Alkycontrol injector. The custom aluminum Abear motorsports valve covers are milled "LSX 438 twin turbo."
The power and torque this engine is capable of making would have demolished most transmissions, so Chuck and Vince at Finishline Transmission built a 4L80E with billet input and main shafts and a 10-1/2-inch, 2,600-2,800rpm stall torque converter. South Bay Driveline built a 4-inch-diameter steel driveshaft to get the power to the Quadrasteer rear end, with two driveshaft hoops along the way. So far, the driveshaft hoops have proven to be nothing more than insurance, but with diesel-like torque on demand, it's peace of mind for Mark when he's running on the street, as well as on the track.
Freshly assembled and with only 50 miles on the clock, Synergy strapped the truck down to its all-wheel-drive dyno. Running a modest 12 pounds of boost and with a conservative rich air/fuel mix, the truck put down 712 hp and 785lb-ft of torque, the next run netted 730 hp and 805 lb-ft. Once the engine is broken in and the real tuning happens, Mark is looking to crank up the boost to get 1,000 hp. So, if you ever find yourself in California's Bay Area, don't assume the Denali cruising next to you on the highway is a weekend toy hauler. Mark's Denali should be one of the quickest street-driven extended cabs out there, and with 18 psi of boost on the horizon, he's set the bar high for his competitors.
Mark would like to send special thanks to all of his friends and the people who helped make his dream truck a reality: Butch, Christopher, Richard, Chuck, Vince, Rick Hallenback, Shannon Robb, Jerry Burdick, Robert Corrigan, and Dave Lamanno.