In fact, the entire engine is essentially production-based, although not entirely stock considering his truck originally came with the 4.8-liter V-8. Schoen swapped to the larger 5.3L, reusing the original rotating assembly with Speed Pro rings fitted to the pistons. Also inside the engine is an LS1 camshaft from his uncle's TA, while the cylinder heads are from an LQ4 6.0-liter engine. They're stock, except for stiffer, LS6 valvesprings taken off an '05 GTO, but more importantly, they have a greater chamber volume than the 5.3-liter heads, which lowered the compression ratio from 9.9:1 to a turbo-friendly 8.4:1. Even the intake manifold is stock, although equipped with 39-pound fuel injectors. The salvage yard-sourced electric fan from a Chevy Corsica blows into the radiator, keeping the pressurized LS engine nice and cool, even under high-load, full-throttle driving adventures.
Low compression helps stave off detonation, but so does the methanol injection system that Schoen rigged up, using a junkyard windshield washer container and a Snow Performance pump. "I inject my own 40/60 mix of methanol and water to cool the incoming air ... [since] the tiny turbo creates a ton of heat at 11 psi," says Schoen. Methanol injection acts as a chemical intercooler, so it saves the use of higher-octane fuel to prevent detonation, which enables more aggressive tuning to maximize horsepower.
"I picked parts because they worked, not where they came from," says Schoen. "There are tons of usable parts that are thrown out all the time; I made use of the ones that helped my project and they've all proven to work just fine."
Backing the turbocharged 5.3L engine is a 4L60E that's been beefed up to support the added torque that comes from the turbo system. Corvette servos from a Blazer's 700-R4 were added to firm up the shifts and add more clamping force to the 2-4 band. The torque converter is yet another take-off part, coming from a stock TrailBlazer (which came with a little higher stall speed). Additional drivetrain components include a Richmond 4.10-geared rearend, fitted with an Eaton TrueTrac limited-slip differential. It spins a set of 18x10 MB wheels wrapped in Eagle F1 tires that-no surprise here-Schoen bought used.
"I couldn't decide on a tire size, so instead of spending a fortune on tires, I scored the F1s for a fraction of the retail cost, just to see how they looked," he says. "I thought it was a good deal." It was; but he bought the wheels while living briefly in Arizona and, after the first winter back in Ohio, the bright finish on them was trashed. Ever the enterprising enthusiast, Schoen scuffed up the wheels and rattle-canned them with a charcoal color that very nicely complements the factory tan color of the truck. The dark rims also enhance the vehicle's slightly sinister, all-business appearance. The only other exterior deviance from stock is a set of 2-inch lowering springs, front and rear.
When it came to tuning his combination, Schoen used tried-and-true HP Tuners software to create a custom operating system, utilizing speed density. "There were a lot of reasons I went with speed density," he says. "One of the most important was the fact that, with a 2-bar speed density system, I had a more user-friendly tuning range, plus the stock MAF is only good for about 10 pounds of boost; also, I just wanted to eliminate another charge pipe connection under the hood." Conveniently, changes in tuning are tapped into the MacBook Aaron keeps in the truck's cab. He also inspects the engine's vitals via-of course-a homemade A-pillar pod containing an air/fuel ratio gauge and a boost gauge. The rest of the cabin is what you'd expect to see in a stock, 6-year-old Silverado.