When you speak to Aaron Schoen about his turbocharged 2004 Chevy Silverado, the same phrase pops up constantly: "I did it myself." His truck is an amalgam of parts borrowed, swapped, and recycled, but all to a stunningly effective result. From its mere 5.3-liter displacement, the pressurized truck engine pumps out 503 horsepower to the tires and has flung the heavy Chevy down the quarter-mile in a rev limiter-abusing 12.9 seconds at 114 mph (with a 2.22-second short time that suggests a gentle launch). Meanwhile, Schoen says he has less than $1,500 into the parts required to develop such power.
"It was a project, for sure, but it was pretty straightforward," says Schoen, understating the level of workmanship. "The real challenge was doing it on a budget." In a nutshell, Schoen scratch-built an intercooled turbo system, using a single turbo and an air-to-air charge cooler, along with a methanol injection system to keep the rotating assembly happy under boost. There are a couple of other things you should know, too. First, Shoen is a graduate of Universal Technical Institute, so he knows a little something about building high-performance combinations, and secondly-and more importantly-the single-stall garage at his apartment complex in Norwalk, Ohio, has only the barest of work benches. There is no six-foot-tall air compressor, no four-post lift, no professional welding equipment, and no $20,000 air conditioned/flat-screen-equipped tool chest. Come to think of it, we didn't even see a lightbulb hanging from the ceiling.
It's a matter of fact to Schoen that he built the truck almost entirely by himself, but it struck us as the type of project that happens with less and less frequency these days. With so many ready-made aftermarket components and a number of competent installation/tuning facilities around the country, many enthusiasts simply do remove-and-replace parts swaps on their cars or simply leave the task to someone else. Schoen says he was inspired by the unique turbo kits of Utah-based Squires Turbo Systems (STS), which mount the turbocharger out of the engine compartment, closer to the rear axle, for easier installation and reduced underhood heat. "I figured I could make something like that, so I started working on it," he says. "The hardest part was I didn't have any of the tools to bend and shape the tubing for it."
The turbo system flows into and out of a Garrett T61 turbocharger (60mm inducer, 85mm exducer) that Schoen picked up used (same goes for the wastegate and bypass valve). Aaron didn't have the tools to fabricate the necessary tubing for the system, so after pre-assembling the turbo and wastegate in the stock muffler location, he took the truck and a couple of silicon hose couplers to a local exhaust shop. He showed them the outlet of the turbo and the inlet of the intercooler, and said "connect the dots." The shop bent the necessary 2.5-inch tubing to accommodate the design. "They did a great job," he says. "It all fit perfectly when they were finished, $30 and a burnout when I left was all he charged me."
Of course, the elements of the turbo system include the flow pipes from the engine's exhaust manifolds, which merge and feed the turbocharger's turbine. From there, more tubing runs to the front of the engine compartment, where the boosted air charge (tuned right now for a maximum of about 11 psi) flows into an air-to-air heat exchanger that came off a '89 Toyota Supra. Then the air is crammed into the 5.3-liter iron-block engine's stock throttle body. An electric pump is required to re-circulate oil from the turbo back to the engine; it returns to the crankcase via a fitting drilled into the oil fill cap on the valve cover. One of the additional benefits of this system design is it retains the stock exhaust manifolds, which saves a big chunk of change, as more conventional systems typically require thick, expensive cast-iron manifolds to support the high-heat turbo.