Thursday, August 17, 2023

Corvette Grand Sport vs. Shelby AC Cobra: A Duel That Only Happened Once (or Twice)



If you'd wandered down the right street during a rare April snowstorm in Philadelphia a few years back, you might have seen this car slide past on the slick asphalt.  "Hmm," you might've thought, "looks like an old Sting Ray hot rod.  Somebody must have wanted to go racing a whole lot..."
Well, somebody did want to go racing a whole lot, and it was Zora Arkus-Duntov, chief engineer for the Corvette program at General Motors.  By autumn of 1962, as the new Corvette Sting Ray was attracting crowds in Chevy showrooms, Duntov and his team of engineers were preparing to launch a lightweight version of the car, with the goal of making 125 examples to qualify as a production car to compete in the SCCA with the Ford-powered Shelby AC Cobras, which were stealing all the glory from Corvettes on the tracks back then…
By late 1963, Duntov's team had built only 5 Grand Sports; the first two were roadsters made from cut-down coupe bodies like chassis #GS002, shown on that snowy demonstration day at the Simeone Foundation Museum.  3 cars were coupes like the one below, now on display at the Revs Institute.  Lacking production car qualification, the Grand Sports were slated to compete in SCCA's C-Modified class, where they were not well-suited to the competition.  At Nassau Speed Week in December, though, a free-form Trophy race was scheduled where the new Grand Sports could run against the Cobras.  Chevy's "production car" program had been based on a modified 327, but at Nassau the Grand Sports were powered by aluminum-block 377 cubic-inch engines with Weber carbs, special heads including hemispherical combustion chambers, and around 480 hp.  In order to match the stopping power of the disc-braked AC Cobras, the Grand Sports abandoned the Sting Ray's drum brakes for Girling discs. And the chassis was a new, tubular one. GM management, unlike the brass at Ford, was shy of direct involvement with racing, so "ownership" of the cars was transferred to Texas oilman John Mecom's team, and a crew of Chevy engineers suddenly decided to take their winter vacations in the Bahamas...
The Grand Sports were claimed to weigh around 1,980 pounds, over half a ton less than the standard Sting Ray.  On race day in the Bahamas, the new Grand Sports beat the Cobras in their first official race appearance.  The photo below may be a sign of the front-end lift that drivers reported at speed, or of the car's eyeball-flattening acceleration...
Shortly after that Nassau performance, GM management pulled the plug on the Grand Sport program, ending Duntov's hopes of getting those 125 production cars.  Grand Sports raced Cobras again, but in different classes, and without success.  Two Grand Sports finished the Sebring 12 Hours run on the first day of spring in 1964, but they ran in a class for prototypes over 3 liters vs. 5 liter GT class for Cobras, and lost, McKean Chevrolet's GS in 18th place behind a production Sting Ray in 16th place, and way behind the Cobras, which took 4th through 6th places. Shelby and Ford would eventually have their final revenge for the Nassau rout, with Shelby qualifying the Cobra Daytona coupe (6 built) as a "production" car like the standard roadster in 1964, and winning the FIA Manufacturers Championship with it in 1965.  
The 3 Grand Sport coupes were the only '63 Corvette fastbacks without the famous "split window" feature.  Rearward visibility took priority over styling, as it would on the '64 and later Sting Ray coupes.  Eagle-eyed readers will also note that this backlight has a more radiused shape to clear the fuel filler, and probably to avoid stress cracks in the thin, hand-laid fiberglass selected for these lightweights. In addition to all the functional slots, vents and louvers, the Grand Sports had something missing on all production Sting Rays, a deck lid (barely visible in the 2nd photo from top).  This was not for luggage (a flat space behind the seats atop the 50-gallon fuel tank would suffice) but for access to the battery and the differential cooler. The huge flares for wider wheels on the Grand Sport interrupt the dominant horizontal crease shown on the standard Sting Ray below…
One feature shared by the standard Sting Ray was a tendency toward front-end lift, a result of the forward-slanting section of the nose.  It's pretty though, and the Sting Ray was the first production Chevrolet to be tested in a wind tunnel...
Half a dozen years earlier, in another attempt to field a serious road racer, Duntov's team had taken their wind-tunnel tested, magnesium-bodied, tubular-chassis Corvette SS* shown below to the 1957 Sebring 12 Hours, where the car impressed drivers and crowd before retiring with teething troubles.  Shortly after that race appearance, GM management decided to comply with a new Automobile Manufacturers Association ban on racing, and the SS was retired, prefiguring Duntov's later disappointments.
Like that SS prototype, all 5 original Grand Sport Corvettes survive, and were gathered for the photo below some years ago at the Amelia Island Conrours; this was before the Simeone Foundation roadster (wearing silver blue paint below) was returned to the blue on white, as-raced color scheme it wore during that romp in the snow.  Despite their abbreviated racing careers, these Grand Sports are probably the most sought-after Corvettes on the planet.
*FootnoteFor more details on that magnesium-bodied Corvette SS, see "Forgotten Classic: Chevy's Corvette SS Ran Before the Ban", posted July 18, 2020. Lance Reventlow's adventures with Chevy-powered Scarab racers are reviewed in "Timing Is Everything: Reventlow Scarab Saga", in the blog archives for 6-2-17. For a look at other special Corvettes that happen to have metal bodies, visit our series of posts on Corvettes bodied in Italy by the likes of Pininfarina, Vignale and Scaglietti, starting with "The Italian Jobs: Corvettes in Italian Suits" (2-24-16), followed by "The Italian Jobs Part 2: The Kelly Corvette Was the First Postmodern Car" (2-27-16), "The Italian Jobs Part 3: Another Eurovision Corvette" (3-10-16), and "The Italian Jobs Part 4: Saved From the Crusher" (3-13-16).  

Photo Credits:
Top and 2nd:  youtube.com
3rd & 4th + 7th & 8th:  the author
5th:  The Revs Institute
6th:  General Motors
9th:  George Havelka
Bottom:  Corvette Info Center

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