Dream Garage: Pratt & Miller Corvette C6RS

Pratt and Miller C6RS LeadFor most performance enthusiasts, the name Pratt & Miller conjures up thoughts of Corvette Racing’s race cars, which have seen remarkable success in the GT-class racing ever since Chevrolet partnered up with the outfit in 1999 to create purpose-built versions of the C5, C6 and C7 for use in motorsport. And when it comes to the pinnacle of road-going production C6 Corvettes, those same enthusiasts would likely name the supercharged, 638 horsepower 2009 “Blue Devil” Corvette ZR1 as the king of the hill for that generation.

However, Pratt & Miller’s brief foray into road car production in 2008 challenges both of these notions. While it admittedly comes up a few ponies short of the ZR1 in terms of raw peak output, the Pratt & Miller Corvette C6RS serves as a showcase of what race car engineers can do with a road car when given free rein to build a vehicle to their exacting specifications.

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Pratt & Miller’s effort to produce a road-going version of the Corvette rode a fine line in terms of marketing the car to the sort of Corvette fans who might be able to afford such a pricey offering. On one hand, they wanted leverage the company’s rich history of designing purpose-built race cars for the Corvette Racing program – a program that had been wildly successful particularly with the C6.R racer, which dominated GT1 and GT2 class racing in its day. On the other hand, they also wanted to emphasize the fact that this was not a harsh, punishing-to-drive race car that was slightly toned down for street use, but rather a well-appointed GT road car that also boasted incredible on-track performance. Image: Pratt & Miller

“The C6RS is what a Corvette can become when not restricted by the requirements of assembly line-based manufacturing,” Pratt & Miller spokesman Brandon Widmer said at the car’s 2008 debut. “With the C6RS, we analyzed every major component of the production Corvette, looking for opportunities to optimize design for performance, durability, quality, and aesthetics.”

But with only seven examples built in total, the term “production model” is used loosely here. Regardless, the C6RS isn’t just a hopped up C6 Z06 – it’s arguably the ultimate modern road-going Corvette (custom one-offs notwithstanding).

What Happens When Racers Build A Road Car  

Let’s get one thing out of the way right from the start – the C6RS wasn’t for the faint of pocketbook. While a ZR1 would cost you about $100,000 off the showroom floor in early 2009, the C6RS was, well, substantially more. How much more? Pratt & Miller would build you one for $187,500 – plus the cost of the customer-provided C6 Corvette.

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Although the company had planned to build 25 examples of the C6RS per year, they would ultimately build just seven cars in total. While pedigree and performance likely weren’t the issue, as the C6RS offered world-class performance that’s still on par with the most modern supercars today ten years on, its price tag likely was. At $187,500 plus the cost of a donor C6 Z06 (buyers could use a standard C6 Corvette as a donor car, but doing so made the conversion more expensive) the C6RS was nearly three times the price of the then-new ZR1, which offered similar straight-line performance from its supercharged, 638 horsepower V8. But at under 3200 pounds with 600 naturally aspirated horsepower, along with upgraded rolling stock and suspension, there’s little doubt that the C6RS could outpace the heavier and less grippy ZR1 on a road course. Image: Pratt & Miller

Given that, Pratt & Miller immediately abandoned the performance bargain territory that the Corvette normally occupies and went straight into the exotic supercar bracket. But it’s that decision to go big that allowed the company to build the car in the first place. “Seven years ago, I started fielding calls for aftermarket parts almost weekly,” Pratt & Miller’s Mike Atkins, C6RS project manager told Autoweek.

“We didn’t want to pursue it because that’s not what we did, and we didn’t want to infringe on GM.” But once given the green light to pursue the C6RS project by Tom Wallace, GM’s chief engineer for the Corvette at the time, Pratt & Miller wasted no time getting to work on the C6RS. Given the expected price disparity between the ZR1 and C6RS, there was little chance of sales cannibalizing one another anyway.

Considering the C6RS’s price tag, you’d expect the transformation from Z06 to C6RS to be a fairly comprehensive process, and Pratt & Miller didn’t disappoint.

Aside from the roof panel, decklid and door skins, all of the bodywork was new, made of carbon fiber, and aesthetically took cues from the C6.R race car.

That aggressive body kit is accentuated by the fact that the C6RS rides a full inch and half lower than a C6 Z06 – low enough that Pratt & Miller saw fit to add a lift system that can raise the car for steep driveway approaches. The same system can also lower the car an additional inch for extra dramatic flair when parked, and the suspension system is further upgraded with Pratt & Miller-tuned dampers, along with heavy-duty wheel hubs and bearings.

"Every body modification has a purpose," Gary Pratt explained when discussing the C6RS's body kit. "The features were modeled on the C6.R race cars, and there are no nonfunctional styling elements." C6RS #003, pictured here, is the second C6RS to be publicly up for grabs after purchase. Among the seven cars built, one was kept by Pratt & Miller and another by Jim Miller, while Jay Leno had a special E85-fueled version built. The other four examples went into private collections. C6RS #003 went up for bid on eBay in May of 2013 and was said to have been owned by the Pratt and Miller Corvette Racing team's photographer, who traveled with the crew for over decade to various race events, including eight consecutive visits to the Circuit de la Sarthe for the 24 Hours of Le Mans. Images: eBay

The interior also saw significant revision as well. Pratt & Miller wasn’t satisfied with the fit, finish, and overall material quality of the standard Corvette’s cabin, so they enlisted the help of Shelby Trim to bring it up to snuff. 160 man-hours were needed to carry out these upgrades, and it resulted in a hand-stitched leather on essentially every touch surface of the C6RS’s interior, while Pratt & Miller also saw fit to replace the stock buckets with a pair of aggressively bolstered sport seats as well as a flat-bottomed steering wheel. They also added Dynamat sound-deadening material to the doors, floor, and other areas of the cockpit.

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While the C6RS offered similar power to the C6 ZR1, how it developed it was significantly different. Rather than using forced induction like GM had with the ZR1, the C6RS used an all-aluminum, naturally aspirated 500 cubic inch power plant that was built by Katech, the same company who developed the motors for the C6.R race cars. The big 8.2-liter mill cranks out 600 horsepower and 600 pound-feet of torque. While off-the-shelf LS7 exhaust manifolds were used with the C6RS, a Corsa exhaust system helped give the engine a distinctive sound. Image: Pratt & Miller

But the power plant is undoubtedly the center piece of the Pratt & Miller C6RS. Their engineers tossed the Z06’s 505 horsepower, 7.0-liter naturally aspirated LS7 V8 – a lovely motor in its own right – and replaced it with something truly legendary. In the LS7’s place sits an 8.2-liter, naturally aspirated V8 that boasts a high-strength 6061-T6 billet aluminum Dart block with linerless Nicom-coated 4.205-inch diameter cylinder bores. The 500 cubic inch engine is built by Katech, the same company that provides the motors for the Corvette Racing team’s race cars.

The Katech engine uses the LS7’s cylinder heads, along with the intake and exhaust manifolds, and it runs the same 11:1 compression ratio as GM’s engine. But Katech adds a custom-forged crankshaft along with forged rods and pistons to the mix. Coupled with a more aggressive camshaft, the entire combination is good for 600 horsepower at 5800 rpm and 600 pound-feet of torque at 4600 rpm, and it’s hooked up to a blueprinted and strengthened Tremec T-56 six-speed transmission with a beefed up Centerforce dual-friction clutch.

Each of the seven C6RS models were hand-built in Pratt & Miller's shop. Along with the requisite performance and body modifications, the C6RS saw upgrades to the interior as well, including hand-stitched leather throughout, along with heavily bolstered sport seats. Another nod to the C6.R race car comes from the C6RS’s wheel and tire package. Like the race car, the C6RS uses center locking BBS forged wheels, which measure 18 x 11-inches up front and 19 x 13.6-inches in the rear, and are wrapped in Michelin Pilot Sport high performance rubber that’s 295mm wide at the front end and 345mm in the rear. Stopping power is provided by the Brembo Grand Tourismo brake system, which is comprised of six-piston monoblock front calipers with 14-inch rotors and four-piston monoblock rear calipers with 13.5-inch rotors. Images: Pratt & Miller, eBay

Performance

Despite the wider wheels and tires, extra sound deadening material, and 1.6-inch wider rear track, the C6RS’s curb weight is nearly identical to that of the Z06 at just under 3200 pounds, due in no small part to the extensive use of carbon fiber in the bodywork.

The resulting performance is decidedly supercar level stuff, even nearly ten years later. Zero to sixty miles per hour is dispatched in the low three-second range, and the C6RS tops out at 202 mph. And while by all accounts the C6RS’s road-holding limits far exceed that of the C6 Z06, the folks at Pratt & Miller were quick to point out that, although this car can absolutely tear it up on a race track, it’s not a race car configured for the street but rather a grand touring machine with a lot of road course capability.

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Despite the extra sound deadening, wider wheels and other additional content, the C6RS’s curb weight was roughly identical to the Z06 at just under 3200 pounds. To help customers wrangle all of the performance out of their C6RS, included with the purchase of the car was a two-day performance driving school at Spring Mountain Motorsports Ranch. Image: Pratt & Miller

“Our goal was to create a Corvette supercar that delivers an extremely high level of performance with extraordinary comfort and reliability,” said Gary Pratt, co-owner of Pratt & Miller Engineering. “The Corvette C6RS was inspired by our Corvette race program, but it’s not a race car for the street. You can take the Corvette C6RS on a 300-mile road trip, or drive it to a track day and run fast laps.”

Legacy

Although Pratt & Miller had originally planned to build 25 cars per year, the price tag of the C6RS kept the car relegated to only the most die-hard, well-heeled Corvette fanatics.

The company would go on to construct just seven examples of the hand-built monster in total, including a one that was built to run on E85 ethanol that was specially built for Jay Leno. A convertible version of the C6RS debuted at the 12 Hours of Sebring in 2008.

Revealed at the 2007 SEMA show, Jay Leno's C6RS was designed to run E85 instead rather than gasoline. "This is the result of an idea we hatched to prove that high-performance cars and alternative fuel technology weren't diametrically opposed concepts," Leno said at the debut. "I love the idea of having 600 horsepower at my disposal, but using a homegrown alternative to gasoline." Images: Pratt & Miller

With the debut of the 650 horsepower C7 Corvette Z06 in 2015 and the seventh generation Corvette ZR1 expected to debut later this year, it’s difficult to say how the C6RS will stand the test of time as new ultra-high performance models continue to be developed by Chevrolet. However, it’s safe to say that, due to its rarity and the impressive engineering incorporated into the C6RS’s design, these cars will hold a special place in Corvette history regardless of what the march of technology brings to Chevrolet’s sports car in the future.

About the author

Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
Read My Articles

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