Words and photos by Cam Benty

In the ’60s, the slogan “wrap your a** in fiberglass” was the calling card of Corvette owners. After all, only two production cars ever came “wrapped” in that magnificent material: the 1963-4 Studebaker Avanti and the Corvette — from its inception in 1953 until now.

All that is about to change.

Fiberglass is heavy, as anyone who as worked with resin and glass matte will tell you. Aluminum and acid-dipped metals were more to the liking of most 1960s racers — just ask any Cobra fan. ’Glass cracks over time from age and vibration, however can be formed into some amazingly cool shapes, as any owner of America’s original sports car will tell you.

So, when J.R. Granatelli and Robert Jones decided to build their concept of the ultimate Corvette, moving away from fiberglass and into carbon fiber seemed like a natural step. Carbon fiber is tougher and lighter than fiberglass, but can be challenging with which to form complex shapes, without expensive equipment. Regardless, their new design featured dramatic exterior changes, all planned to improve on the magnificent efforts executed by Chevrolet’s top engineers.

The front fascia and splitter are unique to the KG Spyder — all parts sold separately through Granatelli Motor Sports, as well. Only the hood and the doors are left from the original Corvette, all added pieces formed from carbon fiber.

“We have a great respect for the Corvette brand, and we are one of only three facilities in California approved by the National Corvette Restorer’s Society for Bloomington Gold level restorations,” says JR Granatelli, President of Granatelli Motor Sport. “For that reason, we looked at the current C7 Corvette platform as an amazing machine, but formulated our own plans to make the ultimate street-legal Corvette.”

The KG Spyder Corvette is a very limited production car, current plans calling for 100 convertible and 50 coupe models to be created at Granatelli Motorsports in Oxnard, California. The low numbers keep the models super special, each vehicle verified with an Authenticity Certificate. They’re a joint effort of Granatelli and Jones, the latter who is also owner of Kompression Wheels and creator of wheel of choice for the KG Spyder. As alluded to earlier, this Corvette sports a carbon fiber body built by Ivan Tampi; only the doors, truck lid, roof, and hood are retained from the original base Corvette on which the KG Spyder Corvettes are constructed.

Wide is the Word

In total, 14 individual, high-quality, carbon fiber components replace the fiberglass bodywork found on the factory-produced Corvette, each part covered by a lifetime warranty against structural defects. The parts include:

• (1) Front Fascia
• (1) Front Fascia Bottom Splitter
• (2) Front Fenders 2″ Wider than stock Stingray per side
• (2) Rear Top Side Skirts
• (2) Bottom Side Skirts
• (2) Rear Quarter Panels 4″ Wider than stock Stingray per side
• (1) Rear Spoiler
• (2) Rear Diffuser

The finished body is a full two inches wider on each side in the front compared to the factory Stingray body dimensions, one inch wider than the Z06 body. In the rear, the car is four inches wider per side than the factory Stingray and two inches wider than Z06. The purpose for the widening is to enlarge upon the factory tire compatibility, The KG Spyder sporting 285/25-20 Michelin tires in the front and massive 325/30-21 in the rear. Kompression SLU-Tessoro model forged aluminum three-piece wheels are 20×10 in the front and 21×14 in the rear.

“Removing the body from the car is really not difficult, as we found during the build up,” says Granatelli. “It’s just a matter of a few bolts. But, the look of the car with the massive tire/wheel combination took some serious design and theory manipulation. As you can see, the front fascia has been completely redesigned, and the splitter below the fascia is both cool looking and has purpose. While the car will do well over 200, it is completely comfortable cruising at 180 mph.”

Topping off the exterior looks is a House of Kolors Black Cherry paint scheme that works in great contrast to the polished and machined styling of the Kompression wheels. Donlyson Auto Concepts in nearby Pasadena, California, applied the paint.

Sticking the Landing

The chassis has for the most part been left alone, with the exception of the Performance Friction high-performance brake pads to improve stopping distance with the factory Z51 brake package and Granatelli-developed high quality, heim-jointed adjustable toe links. With the major oversizing of the rear tires, Granatelli found the car to be a bit “darty” at speed, so adding some additional negative camber helped overcome this issue. The factory toe links are not adjustable.

Power Up

While the suspension modifications are subtle, the engine upgrades are intense. Reworked by Granatelli Motor Sports, the 380c.i. LT engine runs forged aluminum, reworked H-beam connecting rods and fully CNC-ported Granatelli Motorsports cylinder heads (with stock valve sizing), all bolted together using ARP 2000 fasteners. Compression is reduced from the factory 11.5:1 to 10:1 to prepare for power adder installation.

For those who may not remember, the Granatelli family owned Paxton Superchargers from 1957 to 1998. Specifically, J.R. Granatelli is credited with pioneering and engineering the success behind the centrifugal supercharger design.

“We have extensive background with supercharging from our years in the power adder business” notes Granatelli. “For that reason, we selected a Vortech Centrifugal crank-driven supercharger and turned up the wick with 7 psi of boost. The result is a 712 crankshaft hp/660 rwhp, 644 lb-ft of torque. That power flows through a McLeod RXT series dual disc clutch and factory manual transmission (automatic transmission is also available). The rear end is more than capable of handling the increased power and sports 3.31:1 ratio gearing; a very efficient factory cooler helps compatibility with high speed travel.”

The KG Spyder is an innovative result of American engineers looking to improve on a good idea. While the factory-delivered Corvette is strong enough for most, that enthusiast spirit continues to bloom into more capable forms of fast. Where’s the limit? No one can tell, but the KG Spyder could make a serious case to be high water mark in high performance transit!

Source: Granatelli Motor Sports, granatellimotorsports.com