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.
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.
After our photo shoot wrapped up, we went for a ride around Norwalk and we were immediately impressed by what we didn't notice. There were no hiccups, stalling, or stumbling from the engine. The power didn't hit like an on/off switch, either. It came on smoothly and strongly, shoving the heavy pickup down the road with enough urgency that we double-checked to make sure our seatbelt was fastened. You don't have to tell Schoen there are more powerful LS-powered vehicles out there, and he's fully aware that the exterior of his truck isn't exactly blemish-free. He knows it all and so do we. None of that matters when you take into account the ingenuity, craftsmanship, and dedication used to make this project work on a budget.
We used to read such stories 25 years ago in old hot rodder magazines; the backyard specials that, frankly, modern enthusiasts just don't do any longer. But none of those bailing wire specials were electronically fuel injected, nor did they make 500 tire-smoking horsepower. Schoen's does and he can thank one person: Himself. That's what makes his Silverado one of best hot rods we've encountered lately.
2004 Chevrolet Silverado 1500
Owner: Aaron Schoen
Block: LM4/LM7, 327cid Compression ratio: 8.4:1
Heads: Stock 6.0L (LQ4)
Cam: Stock LS1 (2002 model year)
Rocker arms: Stock 1.7 ratio
Pistons: Stock, hypereutectic
Rings: Speed Pro
Crankshaft: Stock, nodular iron
Rods: Stock, powdered metal
Throttle body: Stock
Fuel injectors: Ford 39 lb/hr
Fuel pump: Walbro 255-lph
Ignition: Stock coil-near-plug
Engine management: Stock PCM, tuned by owner
Power adder: Garrett T61
Boost: 11 psi
Intercooler: Air-to-Air (from an '89 Toyota Supra)
Wastegate: XS Power
Exhaust system: Stock manifolds, 3-inch MagnaFlow
Transmission: 4L60E, built by owner
Torque converter: Stock (TrailBlazer)
Front suspension: Eibach springs, stock control arms, sway bar, shocks
Rear suspension: Stock, Eibach lowering kit
Rearend: Stock, 4.10 gear, Eaton TrueTrac posi
Wheels: MB 18x10 front, rear
Front tires: Goodyear Eagle F1 295/45/18
Rear tires: Goodyear Eagle F1 295/45/18
Fuel octane: 93 + meth
Race weight: 4,750 lbs
HP/TQ: 503 rwhp / 535 rwtq
Best ET/mph: 12.90/114
Best 60-ft. time: 2.22
Current mileage: 78,000
Miles driven weekly: 100