Factory Five GTM Supercar - Conversion Factor

Factory Five's Amazing GTM Is A Vette-Based Supercar

Steve Temple Nov 1, 2008 0 Comment(s)
Vemp_0811_01_z Factory_five_GTM_supercar Front_view 1/12

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.

Vemp_0811_02_z Factory_five_GTM_supercar Shifter 2/12

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.

Vemp_0811_03_z Factory_five_GTM_supercar Rear_view 3/12

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).

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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."

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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.)

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