Corvette GTR

Corvette GTR Corvette GTR
Specialty File

Since its introduction for 1997, the C5 Chevrolet Corvette has been selling at a brisk pace. Just as brisk is the pace that aftermarket companies are modifying these Corvettes. To date, we've sampled three tuner-modified C5s.

First, we tested John Lingenfelter's Corvette with a stroked LS1 V-8. It flew. Next came Chuck Mallett's Mallett 435. And recently, we sampled the Corvette GTR, a product of Specter Werkes/Sports of Troy, Michigan, a design and engineering shop.

The Corvette GTR is the result of Specter owner Jeff Nowicki's background as a car designer and weekend racer. Nowicki, 31, was graduated from Central Michigan University in 1989 and began working for GM's design staff the following year. In 1991, he made the clay model for Oldsmobile's Achieva IMSA GTU race car. In 1992, he parted company with General Motors to concentrate on Specter Werkes/Sports, a company he founded in 1990. Specter mostly does contract design work and builds show cars for the Big Three, The Corvette GTR is its first venture in the aftermarket-enhance-ment business.

The wild-looking body transforms any C5 coupe, convertible, or hardtop into a Corvette GTR. Nowicki prefers to start with Corvettes equipped with the Z51 performance suspension.

Nowicki was trying for a more aggressive-looking Corvette when he lopped clay onto an existing C5 and sculpted the car to his liking. Only the hood, the roof, and the rear deck remain stock. The bodywork gives the Corvette something we never thought it needed -- a wider stance. What the added six inches in the rear and three inches up front do is provide more room for bigger tires. The fronts grew from P245/45ZR-17s to P285/35ZR-18s, and the rears went from P275/4OZR-18s to P335/3OZR-18s. (Later GTRs will use 19- inch rear wheels.) Instead of using the Goodyear run-flat tires, the GTR uses Michelin Pilot SXs.

To compensate for the increased lateral traction that the wider tires provide we measured 0.96 g, 0.06 better than stock. Nowicki installs stiffer anti-roll bars front and rear. The GTR comes with a cat-back exhaust system, GTR-embroidered seats, a dash plaque, and custom valve covers. The package, which takes about three weeks to install, including the bodywork, the painting, and all the other various pieces, costs $32,000.

We got excited when Nowicki told us about the souped-up LS1 engine he offers for either the Corvette GTR or an owner's stock Corvette, modified by Katech. The same shop that built this year's Indy-pole-winning Olds Aurora V-8, the motor is basically a stroked LS1 displacing 382 cubic inches, with beefed up internals and an oil cooler. Horsepower is 424, 79 more than you'll find in a stock C5.

The engine mods cost $16,000. They help power the car to 60 mph in 4.5 seconds and through the quarter in 13.0 seconds at 111 mph. The last stock Vette we tested -- an exceptionally strong example -- hit 60 mph in 4.7 seconds and turned the quarter in 13.1 at 111 mph. Lingenfelter's 370 Vette rocketed to 60 mph in 4.1 seconds and turned the quarter in 12.3 seconds at 118 mph. In top-speed runs, the GTR's wide rear flanks held it to 172 mph, 1 mph faster than a stock Vette and 18 mph less than Lingenfelter's stock bodied car.

Overall, we were impressed with the fit and finish of Nowicki's body panels -- they looked factory-installed. But the GTR package is pricey. Our test car, with the GTR package and Katech engine, cost -- gag me! -- $89,131. Nowicki isn't dreaming of mass production; he hopes to make 25 GTRs a year.

Nowicki says our test car's engine was Katech's first try at modifying the LS1 and that later versions will have more horsepower. Good idea, because it needs more juice before we'd put a GTR on a wish list ahead of one of Lingenfelter's Vettes with a $17,995 LS1 engine.