By Steve Temple

Photos by Steve Temple

When it comes to Corvettes, more is better. Not only do many Vette owners have more than one in their garage, they usually accumulate an assortment of Corvette components as well. What to do with them?

Well, no other company has taken automotive recycling to such a fine degree as Factory Five Racing (FFR). Back in the mid ‘90s, the company started out by scavenging about 70 parts off a wrecked 5.0 Mustang to create a low-cost, everyman’s Cobra. This trash-into-treasure formula proved to be enormously successful for several other FFR component vehicles as well, including the mid-engine GTM exotic. This was the company’s first original design, not a replica of any previous model. Even so, the GTM’s low-slung lines are somewhat akin to a GT40, while manifesting its own distinctive and exotic persona.

This model’s custom spaceframe is designed for an LS1 or LS6, but any LS engine can be bolted in behind the cockpit. Of course, a transaxle with adaptor plate must be used in place of the standard transmission, usually a Porsche 911’s G50 or a ZF or Mendeola unit.

In general, FFR recommends using Corvette C5 (’97 to 2004) components, but some customers have found a way to use some C6 parts as well. These include the control arms, spindles, hubs, outer CV joints and brakes. Aftermarket upgrades for those Corvette models are acceptable as well.

Since it’s an enclosed car, having air conditioning is a good idea, so the condenser, compressor and dryer from a factory A/C system is recommended. Other cockpit parts include the steering column (sans the FFR-supplied rim), and assorted handles, hardware, switches, seat belts and the like. Up front, the radiator and fan setup fits in nicely, along with the fuel tanks.

Once completed, a GTM outfitted with even a stock LS engine can achieve supercar performance. FFR touts one LS7-powered version that scorched from 0 to 60 mph in 3.0 seconds. And then blazed from 0 to 100 in 6.6 seconds, with a ¼-mile time 11.0 seconds @ 132 mph! That means a GTM can be built to run faster from 0 to 60 mph than a Ferrari Enzo, a Porsche GT, a Saleen Twin Turbo S7, a Ford GT, and a Lamborghini Murcielago. (And some GM execs have privately admitted the GTM has an unfair advantage over a Corvette, in terms of power/weight ratio.)

All of which brings us to the twin-turbo version shown here, built by SKJ Customs for Bill Farber, using a hot mill from Nelson Racing Engines. Given the car’s overall weight of less than 2500 pounds (about 700 pounds less than a Corvette C6), imagine running an LSX with twin 72mm puffers between the frame rails. Shoveling this much air through the intakes mandated huge volumes of fuel from two separate systems (four rails and 16 injectors, fed by two electric fuel pumps). At 11 pounds of boost, it boasts an output of 1200 horses—and that’s just the beginning, as it can be dialed up to 39 psi with the twist of a knob.

Even without running higher levels of boost on race gas, the power-to-weight ratio is skewed toward the extreme. Funneling this flood of power to the rear wheels is a custom-built transaxle for a Porsche 997 GT-2. This unit has to be mounted upside down, since the Porsche is rear-engine and the GTM is a mid-engine cruise missile.