Modifying a Corvette is a simple affair. Simple, that is, if you know how to add the right parts to your Vette-or if you count on an expert Corvette shop to "do the math" for you. Tommy Calhoun entrusted his '05 Corvette to Altamonte Springs, Florida's Next Level Performance, and he ended up with a twin-turbocharged LS7-powered Vette that twisted the dials on NLP's chassis dyno to over 855 horsepower.
Though Tommy's owned other cars that he's upgraded for more power, this is his first-ever Corvette. "I've always hot-rodded and raced most of my life, and I thought I'd play around with the Corvette a little bit," he says from his Chancellor, Alabama, home.
That "playing around" started with a ProCharger supercharger atop the '05 Vette's original LS2 engine, which boosted that 6.0-liter V8's output well over its advertised 400hp figure. But, Tommy was looking for even more power. "We took that engine out and put an LS7 engine in it, and put twin turbos on it," he says. Not just any LS7, mind you. This one is specially modified, boasting a Callies forged steel crankshaft, a special-grind Comp Cams hydraulic roller camshaft, and plenty of other heavy-duty hardware.
What kind of turbochargers are on this LS7-and where are they? "They're APS turbos," says Tom of the ones that he had Next Level Performance (NLP) install. "They're right under the engine, at the end of the exhaust manifolds. They don't use headers-they run off the end of the manifolds." Two turbochargers can produce quite a lot of boost, which is what the APS units do to the output on Tommy's LS7. He has three different levels of tuning for the C6's ECM, each with a different level of boost. "One of 'em is an 8-pound tune, that makes 705 horsepower at the rear wheels," he says. "Then I've got another tune that is a 12-pound one, and it makes about 856 horsepower at the rear wheels." What about his third tune? "I keep it under my hat-it's a hush-hush deal," he says with a smile.
More power coming out of the engine bay calls for upgrades to the C6's transaxle, and that's where Next Level Performance called in a specialist: Daleville, Indiana's RPM Transmissions. They built a modified GM 4L60E four-speed automatic gearbox, with a 2800 stall converter among the upgrades, which NLP installed in Tommy's C6. The rest of the chassis is either stock '05 C6, or later-vintage original C6 parts that bolted on. "Bolt-on" is a phrase that best describes how all the mechanical upgrades went in and on this first-year C6. "Believe it or not, they did it real quick," Tommy says about the time NLP needed to do the work. "I thought that it was going to be a long, laid-out deal. As far as the turbos, they did those in about a month and a half."
A similar six-week period was all that Burke's Corvette in Maitland, Florida, needed to upgrade this '05 Corvette into a ZR1 look-alike-once again, with parts that were easy to install. "Everything bolted up real nice and neat," Tommy says about the body modifications, which needed no "remedial" work to fit on his car. "They said that they didn't have to change anything, or do any cutting, sanding, or any bodywork to them. The body pieces fit perfectly." No wonder-Burke's used OEM Corvette ZR1 body panels, which they finished in the same early-'05 Precision Red that Tommy's Vette was painted at Bowling Green Assembly. Inside, other than a pair of auxiliary boost and fuel-pressure gauges mounted in a pod on the driver-side A-pillar, the interior of Tommy's C6 is all original.
Need you ask how fun it is to drive? "It's really nice and easy and fun," says Tommy. "It's got a lot of power. I drive it around with the 705hp tune." He adds, "It's got a fairly good lil' ol' cam in it, in the .600-inch lift range, but the car runs real good in town." So good, he says, that it gets about 26-27 miles a gallon on the highway, and around 18-20 miles a gallon in town. That's in a car that has already turned sub-nine-second times in the quarter-mile, with runs in the eights a distinct future possibility. But he does offer one caution about all that power on tap. "It's really dangerous, though, if you don't try to hit passing gear to go around anybody, because it'll turn around in the road."
If the 400 (advertised) horsepower that your stock '05 Corvette's LS2 isn't enough or you plan on upgrading whatever vintage Vette you have, Tommy offers this advice: "It's all according to how much power you want to run around with on the street," he says. "Mostly, if you want to run around 550 or 600 rear-wheel horsepower on a 427, you can do that with a cam-and-head package." Not only does he recommend the APS turbochargers that his '05 Vette has on it now, but also ProCharger superchargers, like the power-adder that the APS units replaced. "I've run them on a couple of my vehicles, and I've had good luck with them." But Tommy says that there's also one big factor: Money. "By the time you buy an engine and turbos, you've probably spent $40,000-$50,000 on them." he says. "It's all according to what people really want and what kind of money they want to spend."