The 1957 Chevy Corvette SS, known internally at GM as Project XP-64, was developed under the watchful eye of Zora Arkus-Duntov, who would soon become Chevrolet’s Director of High Performance Vehicles.
The whole thing started when Harley J. Earl bought the 1956 12 Hours of Sebring-winning Jaguar D-Type with the idea of installing a Chevy engine in the car and taking it racing. Naturally, Arkus-Duntov thought it would be a better idea to create a purpose-built Chevrolet racer to showcase Chevy performance. Earl liked the idea, and the pair secured Chevy GM Ed Cole’s stamp of approval. Zora would build two racers under the internal moniker Project XP-64, later officially known as the Chevy Corvette SS. One car would be complete with bodywork and drivetrain suitable for competition and display purposes, and the other a prototype with partially completed bodywork, called The Mule.
A select team of specialists got to work on the Chevy Corvette SS straight away, using several European race cars for inspiration, with the goal of completing the car in time to compete in the 1957 racing season. The focus was on aerodynamic bodywork and light weight, and to that end, the Corvette SS received magnesium bodywork, a chrome-moly tube frame inspired by the Mercedes-Benz 300SL, fully independent suspension complete with a de Dion rear setup, aluminum drum brakes with inboard rears, magnesium knock-off wheels, a magnesium oil pan, flush hinges on the front and rear clamshells, a cut-down plastic windshield, two low-back seats constructed of aluminum and vinyl, and a streamlined combination headrest and roll bar. Topping it all off was a Plexiglas airplane-style canopy.
Powering the Chevy Corvette SS was a 283 cubic-inch Small Block stuffed full of high-performance goodness, and fed by Rochester Ramjet fuel injection. Many of the parts were crafted of aluminum including the solid lifter heads, radiator core, water pump, and clutch housing. Exhaust headers fed into high flowing side pipes. The 283 managed to crank out 300 horsepower, and tipped the scales at 450 pounds, or around 80 fewer pounds than a standard Corvette 283. Backing the Small Block was a close-ratio four-speed with a lightweight aluminum case. A plastic gas tank held 43 gallons.
The 1957 12 Hours of Sebring was the shakedown test for the Chevy Corvette SS. The day before the race, Juan Manuel Fangio had taken The Mule for a test drive, immediately setting a Sebring lap record of 3:27, or 2.4 seconds faster than the fastest lap set by Mike Hawthorn in a Jaguar D-Type the year before. At that time, the starting grid was determined by engine displacement, not lap time, so the Corvette SS was at the front of the pack. The two drivers for the race were John Fitch and Pierro Taruffi.
The Chevy Corvette SS was an entirely new concept with many experimental components, so issues were expected. The Corvette SS created a huge gap in front of the Jag D-Types on the straights, but the experimental braking system was difficult to modulate and locked up frequently, creating flat spots on the tires. The engine kept dying on Fitch due to a faulty coil, forcing lengthy pit stops. The rear suspension chattered and the tires rubbed the fenders over bumps. On top of all this, the cockpit was like an oven. The SS retired after just 23 laps.
Despite the single race career of the Chevy Corvette SS, Ed Cole was quoted as saying, “We are quite pleased with the performances of the Corvette SS. The run at Sebring gave us an opportunity to observe, under severe operating conditions, several components we were interested in testing. It proved a design of great promise. When some elements showed signs of deterioration, faster than we thought they should, we felt it best to stop and observe these components rather than continue to point of failure which would complicate further study.”
The Chevy Corvette SS showed Duntov and the Chevrolet Engineering staff what was possible, what worked, and what didn’t. A memo drafted in late March 1957 outlined changes that would need to be made to the SS in preparation for the 24 Hours of Le Mans endurance race in June. Despite its light weight, the magnesium body conducted heat into the cockpit, cooking the drivers. This was exacerbated by the side exhaust system. But it didn’t matter as General Motors joined with the rest of the American brands that formed the Automobile Manufacturers Association in an agreement to cease all involvement in factory-supported competitive motorsports. Its racing days were over.
The Chevy Corvette SS would become a feature in a number of museums and at motorsports events, just not in a competitive nature. It graced the cover of Sports Cars Illustrated and Motor Guide, and Road & Track magazines. Zora Arkus-Duntov would take the Corvette SS to GM’s Mesa Proving Grounds in 1959 and post a blistering 183 mile per hour top speed, a testament to just how capable the SS was.
The Mule would be sold to GM designer Bill Mitchell, eventually becoming the underpinnings for the Project XP-87 Stingray Racer. It would be privately campaigned by Dr. Dick Thompson, winning the 1960 SCCA National Championship.
In 1967, the Chevy Corvette SS would wind up at the Indianapolis Motor Speedway Museum. Duntov had managed to keep the car hidden from GM accountants, almost surely saving it from the crusher. The SS would be featured at Bloomington Gold in 1984 and 1985. It was freshened in the mid-1980s, before appearing at the 1987 Monterey Historic Races, with John Fitch and Duntov completing a parade lap around Laguna Seca. The SS would be featured in a number of magazines, and at myriad events and museums including the National Corvette Museum.
The Chevy Corvette SS is being offered to the public for the first time by RM Sotheby’s at their Miami event February 27th and 28th.
Comments
Wasn’t this car also in Elvis Presley’s movie Viva Las Vegas, pained red?
You are thinking of Clambake-that was the XP-87 Stingray concept car.
No that’s was a 62 Elva MK 6 Maserati in the movie
I was at Laguna Seca in ’87 when the SS was there. It may have made a “parade lap” but I don’t remember that. I remember two “hot laps” and then seeing the car up close in the pits. I was quite surprised when I saw the tires. They were old Firestone racing tires that said “Gum Dipped” on the sidewall. The car was the filmed in the pits for a TV show that was popular back then-I don’t remember the name of it but I have it on a VCR tape somewhere.
A correction to the above article that mentions “solid lifter heads”. The engine had experimental aluminum cylinder heads and a solid lifter camshaft.
Very neat car!
When “Car Guys” ran GM.
And when Gm had style
Did not realize I was walking past a 5-7million dollar car in the Corvette Museum… Glad I snapped a good pic of it while I was there last year!