GM's First Purpose-Built Race Car Was Built For The Father Of The Corvette
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- 1957 Chevrolet Corvette SS Project XP-64 Quick Facts
It goes without saying that the Chevrolet Corvette is about as American as you can get when it comes to cars. In the States, it can be argued that no single car has been able to capture as many hearts and instill as intense a passion for cars and racing as the humble 'Vette, and it's done it all while being relatively affordable, unlike supercars from overseas. It's no wonder, then, that this is why Corvette is referred to as "the working-class hero".
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The Corvette's history began in the early 1950s, and it wasn't a flying start, either. After it received a power boost, the Corvette surged in popularity. By the late 1950s, Chevrolet was interested in taking the Corvette a bit further, into the jaws of international racing. However, not just any ordinary 'Vette would do, so Chevrolet built a special one on behalf of the Corvette's founder and Chevrolet itself: the 1957 Chevrolet Corvette SS Project XP-64.
1957 Chevrolet Corvette SS Project XP-64 Zora Blue Rear Wheel and Sidepipe
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The following article contains information gathered and cross-referenced from various reputable sites.
One Of The Only Corvettes To Wear An "SS" Badge
1957 Chevrolet Corvette SS Project XP-64 Quick Facts
- Built to compete in various internation racing series'
- Features a fuel-injected small-block V8 engine
- The first factory-produced General Motors race car
- Its chassis only weighs only 180 pounds
1957 Chevrolet Corvette SS Project XP-64 Zora Blue Front Angled View
Once the Corvette was rescued by Chevrolet's release of the Turbo-Fire small-block V8 from the throes of potential discontinuation, questions began to arise regarding how promising of a racer the Corvette could be. On top of that, a GM icon by the name of Harley Earl, was interested in taking the Corvette to new heights, as well, and devised a plan to get the top execs at GM headquarters to agree. A Jaguar D-Type bluff and a set of handshakes later, Project XP-64 was off and running with Zora Arkus-Duntov, the proverbial father of the Corvette, heading up the project.
While the XP-64 was based on the Corvette, almost every part of it wasn't shared with the production model. It featured a completely new tubular chassis made out of magnesium, with its designers taking inspiration from the Mercedes-Benz 300SL. Its motor, a 283-CID (4.6L) small-block V8, featured GM's revolutionary Ramjet fuel-injection system. Along with the fancy engine, the XP-64 also utilized a then-uncommon suspension design, which ensures the XP-64 was able to grip the tarmac as firmly as possible while on the track.
Two Project XP-64s would be built; one for the track, and another known as "The Mule". The Mule was a working prototype that served more as a testbed, while the Corvette SS, pictured above, was used in the project's brief racing career.
The Specs
1957 Chevrolet Corvette SS Project XP-64 Zora Manifold
The XP-64's party piece was its small-block V8 which, on top of boasting a revolutionary mechanical fuel injection, was almost entirely made from aluminum, including its water pump, cylinder heads, and radiator core. A magnesium oil pan was also present, along with a set of solid lifters. Each one of the XP-64's pistons featured its own exhaust pipe, all eight of which would be fed backward before joining together to form its dual side-exit exhaust system.
Engine | 283-CID (4.6L) NA V8 |
|---|---|
Horsepower | 310 hp @ 6,000 rpm |
Torque | 295 lb-ft @ 4,400 rpm |
Bore x Stroke | 3.875 in x 3.00 in |
Compression Ratio | 9.0:1 |
Top Speed | Up to 180 mph, depending on gearing |
Curb Weight | 1,850 lbs |
To supplement its 283-CID V8, Arkus-Duntov's team supplied the Corvette SS with a four-speed close-ratio syncromesh manual transmission. Having a close-ratio gearset in a transmission meant for a race car means it can stay on the power more, and get on the power quicker. However, they can spell trouble on racetracks with long straights, because you can suddenly find yourself without any more gears and at the redline well before your car would normally run out of steam.
GM small block V8
The XP-64 was also a testbed for many aerodynamic features we see today. The most apparent example of aero design on the XP-64 is its massive air intake, which is shaped like an old-school jet engine that sits atop the car, just behind the driver's compartment. It was designed in such a way to allow air to effortlessly glide over it, while also ramming loads of fresh air directly into the engine bay.
Its Racing Career
Upon the Project XP-64's completion, GM was ready to throw it to the wolves. Its first competition took place at the 1957 12 Hours of Sebring. Initially, the XP-64 was to be piloted by Carroll Shelby and John Fitch, but Shelby decided to drive for another team, apparently unsure the XP-64 would even make the race, as the car was finished just a week prior to the off. So, a man called Piero Taruffi, an Italian, replaced him. In order to ensure the Corvette SS would be ready to race, Arkus-Duntov shipped both it and its twin, in case part swaps would be needed during the race.
1957 Chevrolet Corvette SS Project XP-64 Zora BW Racing
However, even with the last-minute fixes and clever mechanical maneuvering, the Corvette SS wouldn't have a good start to its racing career. It did not finish the 1957 12 Hours of Sebring due to a litany of issues. First, its experimental, aluminum brake system failed, and then its engine died due to a failed ignition system. These issues were fixed only for the rear suspension to begin failing. At this point, Arkus-Duntov demanded the Corvette SS be brought into the pits and retired from the race.
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Unbeknown to Arkus-Duntov, Harley Earl, Ed Cole, or any other American automobile designers, for that matter, factory-sponsored auto racing would soon be banned. Shortly after the Corvette SS's Sebring failure, the American Manufacturer's Association unanimously agreed to ban factory-sponsored auto racing en masse, ending the Corvette SS's career on the racing circuit. However, despite this, the Corvette SS was considered a success due to the sheer amount learned from its Sebring experience, along with what Chevrolet was able to learn from building it.
The Bill Thomas Cheetah: Another Corvette Racing Legend
A few years after the Corvette SS tried to get into racing, another Corvette-based racer tried to enter the fold: the Bill Thomas Cheetah. Bill Thomas, a race car builder out of California, started his career modifying Corvettes for racing in the late '50s. By the early '60s, he'd started his own company called Bill Thomas Race Cars. The idea for the Cheetah came about as a way to directly compete with Shelby's Cobra, which was beginning to dominate racetracks at the time.
1964 Chevrolet Corvette Cheetah BW Front Angled View
The Cheetah was built on a tubular chassis featuring a then-new type of welding meant to increase the strength of its structure. It also boasted a 327-CID (5.4L) Chevrolet Corvette-sourced small-block V8 producing 360 horsepower and 350 lb-ft of torque. Over its life, a total of 33 Cheetahs were built out of 100 planned. Customers were able to specify what they were planning to do with their Cheetahs, with most going for racing, while others were interested in using it as a road car only. Bill Thomas Race Cars would then tailor the car to the customer's wants.
corvette cheetah front silver
The Cheetah's time was short-lived, however, as racing rules regarding homologation changed in 1964, upping the number of road-going versions of any given car required for qualification from 100 to 1,000 units. This quickly, and abruptly, ended the Cheetah project, and GM pulled all support from Bill Thomas Race Cars shortly thereafter. BTRC carried on building Cheetahs for a short time, with the last one having been ordered in 1965.
Sources: GM Heritage, Hemmings, RM Sotheby's, Chevrolet.
