Driving the Ultimate Naturally Aspirated Corvette

Pratt & Miller's C6RS is a roadgoing C6.R.

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Richard Prince

IT LOOKED LIKE A SCENE RIGHT OFF a Hawaiian shirt, even if we were in Florida: Full moon rising over palm trees, big orange ball of sun sinking slowly beneath the horizon. Unfortunately, it wasn’t sinking quite slowly enough, for our purposes.

This story originally appeared in the July, 2008 issue of R&T - Ed.

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Seems R&T’s Detroit Editor, Shaun Bailey, and I were in a race against time, trying to finish testing the Pratt & Miller Corvette C6RS on Sebring’s famously long and bumpy back straight before total darkness set in.

We lost the contest, and Shaun had to make his last slalom runs with the big Corvette roaring through the cones in a slashing glare of headlights. Not ideal, but—when you think about it—what could be more appropriate than testing this particular car after sunset at Sebring?

Pratt & Miller, after all, is the New Hudson, Michigan, company that builds Chevrolet’s official racing Corvettes, and they’ve won seven Sebring victories in GT-1 (not to mention five class wins at Le Mans and one at Daytona). These guys— Gary Pratt and Jim Miller—know how to make a car run around Sebring. And stay running for 12 long hours, well after dark.

And now they’re building a street car for those well-heeled customers who desire a civilized grand touring Corvette infused with Pratt & Miller’s legendary racing DNA. The formula is simple: Bring P&M your stock Corvette Z06 (or standard C6 Corvette, if you desire a convertible), hand over a check for $187,000 and the folks from New Hudson will transform your car.

Pratt & Miller hopes to build about 25 of these cars per year and has already sold six. Gary Pratt invited us to sample one of their cars—a test mule in the final stages of development—before the finished products are released in a couple of months. He told us the Pratt & Miller race team would be practicing for the Sebring 12 Hours in late February, bringing along no fewer than three of their new street cars for development testing—a flat-black test mule, Jay Leno’s Black Z06 Coupe and a yellow convertible especially built for Jim Miller himself, with automatic transmission.

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At the track, Gary Pratt and Program Manager Mike Atkins gave me a technical tour of the car.

So what, exactly do you get for your $187K?

Quite a bit, actually.

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Richard Prince

First, the engine stuff. It’s a naturally aspirated 500-cu.-in. (8.2-liter) engine with an aluminum short block from Katech Performance (4.2 x 4.5 in. bore and stroke), but the heads, oil pan, intake system and drive system on the front of the engine are all stock Chevrolet Z06 items. Crank and rods are forged steel. The compression ratio is 11.0:1 and power output is 600 bhp at 5800 rpm. Torque is 600 lb.-ft. at 4600 rpm. The transmission is a blueprinted Z06 6-speed box, made smoother and quieter using Cadillac technology.

Surrounding the powertrain is a cleaned up and neatened engine compartment with a second dry-sump tank added for extra volume, racing-type spigot fittings on all fluid lines and an oversized DeWitt aluminum radiator with dual fans. Beyond that frontier, all is carbon fiber.

Well, almost all. The doors, rear deck and roof are stock Corvette plastic, but the lowered fenders, inner fenders, hood, spoilers, brake ducts and fully functional ram air scoop on the nose are all carbon fiber. The nose has a “waterfall” outlet for radiator and engine heat, and there are top louvers and side vents on the fenders, as well as a carbon-fiber front splitter, rear diffuser and underwing.

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Basic chassis construction and suspension layout are stock Z06, but Pratt & Miller has installed its own—softer—composite transverse leaf springs front and rear. The more civilized ride characteristics are balanced by an air shock system from ArvinMeritor with what it calls Dynamic Height Control that stiffens the car in roll and can dynamically adjust the car’s ride height. There’s a Drive setting at a nominal 4.25 in., a High setting for rough roads or driveway dips at 5.5 in. and a Park position that settles to 2.25 in. when the engine is off, to give the car that slammed, evil look from curbside.

Track is 1.6 in. wider than stock, thanks to wider BBS wheels and changes in camber and caster adjustment. P&M makes its own heavy-duty center-lock hubs, and the brakes are a heavy-duty Brembo Gran Turismo system with monoblock calipers and aluminum-hat floating rotors. Tires are Michelin Sport Pilots, 18 in. at the front and 19 in. at the rear.

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Richard Prince

Despite all its carbon fiber, the 3205-lb. coupe is 1 lb. heavier than a stock Z06, only because the P&M car carries 60–70 lb. of sound-deadening material for quieter travel. An all-leather interior and two-tone leather seats with more lateral support add to that luxurious ambiance. Slip behind the wheel, snick the wonderfully slick, succinct gearbox into 1st with a short throw, move off and the first thing that impresses you is low-end civility. The engine growls along with almost glassy smoothness and does nothing abrupt or tricky when you get on it. The engine is not lumpy or oafish in any way and has none of that big, nasty rat-motor feel, but revs with a smooth thrum overlaid with a nice muted exhaust bark. It helps that the car has standard Corvette stability and traction control, though the latter can be turned off. “But you don’t want to,” says Mike Atkins, “or the car will smoke the tires and go sideways.”

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Redline is 6200 rpm, but above about 3000 the car really starts to sound and feel ferocious. Bury your foot in it and the C6RS shrieks down the road in a “Holy Smoke!” (this is a family magazine) burst of hard acceleration that promises limitless road narrowing speed, forever and ever, amen.

It’s essentially a dual-personality car (as advertised), both docile and easy to drive around town and fearsomely fast when you get serious. Nothing happens by accident—the transitions are all very linear— but the dark, violent side is always on tap. The C6RS is kind of like a werewolf with a really good brand of hair conditioner. Smooth and well-groomed, but the eyes are still burning red.

On the track, I found the car marvelously easy to drive, balanced and grippy, and a kick in the pants on the straights. It’s surprisingly refi ned, with a good driving position, ideal pedal placement and a superb gearbox. I turned the traction control off, but couldn’t feel any real difference. I attributed this to the excessive grip available at our modestly mandated lapping speeds, but it later turned out the TCS couldn’t be turned off, due to an internal electrical glitch in the standard Corvette system.

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Shaun Bailey made this discovery when he tried to skidpad the car and achieved only 0.86g because the system wouldn’t let the car rotate properly in a tight circle. He tried the Leno car—which was working normally— and instantly generated an excellent 0.99g.

Later in the day, after regular practice hours, I went out on the track with Ron Fellows—multiple Le Mans and Sebring-winning team driver—behind the wheel.

If you haven’t been racing lately but imagined you were driving somewhat quickly, you need to get into a Pratt & Miller Corvette with a professional driver who’s just come in from a full day of practice at Sebring and has the place wired.

I rode with Ron for several laps and he compressed the distance in a way that would give the average suburban commuter seizures from stark terror. Even I (yes, your fearless reporter) began wishing for a helmet and full belts as we braked hard from 149 mph for the big hairpin at the end of the back straight and watched the walls and Armco loom large at window-side.

Meanwhile, Fellows chuckled and shook his head at the lack of exit speed from the malfunctioning TCS. Truth be told, I was perfectly happy with our exit speed. In any case, the car makes up for it—in spades— when the road straightens out.

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Richard Prince
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Later, I went for a street drive in Jim Miller’s yellow C6RS convertible, which has an automatic transmission but a working TCS switch. And I soon discovered that driving with the traction control off is an exercise in nose pointing and attempted road re-alignment. The car should be well aimed and have room to maneuver when you stand on it. It’s kind of like trying to aim a Thompson submachine gun on full automatic—you have to compensate for climb and drift.

Except for that experience, the convertible feels just the slightest bit less intense than the coupe, and heavier—which it is, by 305 lb., thanks to its steel frame. It seems a little more serene, but I suspect some of that is from the breeze dispersing mechanical noise. I also did a short drive in the Leno car, just long enough to ascertain that it’s pretty much like the test mule, but with much nicer glossy black paint.

With daylight fading, Shaun tried—as mentioned earlier—to gather all his test numbers on Sebring’s back straight, but the darkness made accurate slalom runs difficult and he felt the car could do better in daylight and with TCS disabled. Later, it was discovered by the team that the TCS malfunction wasn’t actually a malfunction. Wheels were changed without the pressure sensors installed—and without detection of pressure you cannot shut off TCS.

Even so, prospective buyers of this car can rest assured it’s plenty quick and extremely agile. Those who require just a little more performance should probably consider applying for a seat on the Pratt & Miller race team and lapping Sebring in one of those yellow cars with a number on the door. But then, of course, it won’t be as nice to drive on vacation.

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