AT last year's SEMA show, we came across an intriguing car, one that paralleled some past musings of GM designers about alternative Corvette designs. In the Meguiars' display, located right next to the GM booth, American Super Car showed off a '63 Sting Ray coupe with a midmounted, 925hp twin-turbo mill, among many other mods. Some might consider this engine relocation to be outright sacrilege, but there have been at least two Chevy-sanctioned one-offs-the XP-882 and CERV-III-that embraced the same logic.
Now add to that short list the GTM from Factory Five Racing. Rather than being constrained by the freight-train inertia of a large corporation, this innovative firm, known as the most successful Cobra replica manufacturer in the United States, is light on its feet. After all, it took some fancy footwork to develop the GTM supercar, which boasts a striking silhouette, a track-tuned suspension, and a midmounted Corvette engine (the GTM initials stand for "Grand Touring Midengine"). In addition to thinking outside the box (in truth, there is no box with Factory Five), the company went to the effort and considerable expense of wind-tunnel-testing the car's unique body design in order to ensure sufficient downforce and safe handling at triple-digit speeds.
Getting back to the engine layout, while it will undoubtedly prove anathema to some Corvette purists, the GTM's midmount configuration actually makes sound engineering sense, creating better balance and handling thanks to an improved "polar moment of inertia." Technical esoterica aside, the bottom line is that a mid-engine car puts the weight right where it should be to optimize performance.
Looking at the GTM from another perspective-that of a potential project car-any Vette fan worth his salt knows the value of C5 components. Even a trashed car is a treasure, a phoenix ready to rise from the ashes. And here's an ideal platform for repurposing those finely tuned components. The only foreign-made piece in the driveline of this home-brewed exotic is a Porsche 911's G50 transaxle (various U.S.-built units are currently under consideration as well).
Giving new life to proven performance parts is a well-worn path for Factory Five. Since the '90s, the company has been known for building affordable replicas of Shelby's enduring Cobra from 5.0 Mustang cast-offs. The company is quick to emphasize, though, that the ladder frame on the Cobra and the GTM's tubular spaceframe are new, custom-designed platforms.
Some might wonder why Factory Five made such a radical change in its choice of engine brands. Of course, Vette owners likely wouldn't question the switch from a Blue Oval to a Bow Tie powerplant, but how about the risky business of creating a completely original vehicle to house it? Factory Five's David Smith sums up this move succinctly: "The number of GM performance enthusiasts is a much larger market," he says, "and I didn't want to make another replica."
Admittedly, gaining acceptance for a custom design is a high-wire act, because there's none of the "borrowed interest" factor inherent in imitating the body lines of, say, a Ford GT40 or a Lamborghini. But Factory Five has one big point in its favor: a loyal and enthusiastic band of repeat customers. Indeed, Smith points out that GTM orders are currently booked ahead for a year-and-a-half, nearly all to owners of Factory Five Cobra replicas who are willing to make the jump to a Corvette-derived supercar.
We visited Factory Five a few years ago when the car was still under development, and Smith allowed us a sneak peek into the company skunkworks. Countless hours of shaping went into the body, and wind-tunnel data verified the functionality of the shape, recording 320 pounds of downforce at 150 mph. (By way of comparison, note that early versions of the GT40 had a disturbing tendency to literally lift the nose off the ground at high speed, so much so that the car would only track in a straight line.)
"Above all, we want our GTM to be safe to drive at high speed," Smith emphasizes. We can vouch for that, having manned the wheel of his personal race car (the stealthy black one shown here), which is fitted with a 400hp LS6 engine from an '04 Z06 and a five-speed G50. It goes ballistic in a blinding blink, rocketing from 0-60 mph in 3.2 seconds. It'll wind out to well over 160 mph in top gear, and the stock Corvette brakes bring the GTM to a clenching halt in only 111 feet from 60 mph. Street tires deliver 1.05 g's on the skidpad.
For the hard-core competitor, even more-impressive performance figures are attainable with an LS7 and a six-speed version of the Porsche trans. (How does 0-60 mph in 3.0 seconds grab you?) However, during extensive testing at the Bondurant School of High Performance Driving, chief instructor Mike McGovern noted that the standard LS6/five-speed setup has a more useable powerband on a road course, as well as an easier shift action.
At speed, the steering is remarkably light and sure, the chassis tight and stable. We whipped through the slalom, and it felt like the car was tethered to the apexes. Yet on a turning circle, it smoothly transitioned to a forgiving understeer near the limit, rather than trying to swap ends.
The GTM is admittedly a bit noisy in the cockpit-perhaps not surprising given that the engine sits right behind the nape of the driver's neck-but there's none of the rickety ride you might encounter in some home-built specialty cars.
So, how much will this level of Vette-powered performance set you back? The basic component package is only $20,000. Dollar amounts for the required Corvette pieces will vary, depending on which model you select and its condition, but any '99-'04 C5 will suffice. Basically, the items required include the engine, exhaust, suspension (minus the leaf springs and shocks), brakes, steering column, radiator, fuel tank, computer, wiring, and wheels and tires, along with related hardware. The G50 transaxle can be had for as low as $2,500 on eBay, if you look hard enough.
Of course, that all might appear simple on paper, but the actual buildup takes at least 350 hours, Smith estimates. Still, that's far less time than those one-off, midengine Corvette concepts mentioned at the outset. Not only that, but the GTM is a real, driveable car that's emissions-exempt in most states. Damn tradition-full speed ahead!