Heritage/History: The Grand Sport Corvette made it's first appearance early in the 1963 season in the C-Modified class with a production 360 HP 327 Fl engine in its lightened2000 pound body. It raced the season as a "stock" appearing racer. The season finale was held at Nassau each year with a "no holes barred" week of races on the island where all the teams could compete against each other using all of the latest high tech performance parts that were other wise banned from regular club racing. When the Grand Sport made it's appearance at Nassau, it looked as if it had been given a big injection of steroids. Flared fenders, hood scoops, wider wheels and tires, and other visible changes only touched the surface of the technological advances that were in these Grand Sports. Under the hood was found an all aluminum 377 cubic inch small block with 58 mm side draft Weber carbs. These aluminum engines were of the second casting batch from Chevrolet's Research and Development department. There were 12 of these castings made. They were identified by the single letter "A' through "L" which was stamped on the traditional location on the passenger side of the engine block. This engine used in the Grand Sport is letter "F" in the series. These all aluminum engines were shared with Jim Hall's Chaparral, but his sports racers used smaller48mm webers that were more suited to the RPM requirements of the unique automatic transmissions that were in these revolutionary racing cars. The Grand Sports either annihilated the competition or won everything in sight that week at Nassau. The teams were so confident with their wins, that preparation began for the 12 hours of Sebring. All three coupes enteredthe 196412 Hours of Sebring. Roger Penske and Jim Hall shared a newly painted white Grand Sport. This car was the most prepared car of the group. A pneumatic system was installed on the car which happened to be one of the earliest applications of an air driven jack device on any sports racer. This pneumatic jack system not only reduced pit stop times but also eliminated any damage to the fragile fiberglass body and tube frame that could so easily occur when changing tires. The external fittings for the air jacks are seen on the right front fender. The attention to detail paid off , for this Grand Sport finished 1 st in it's class! The '64 season ended with the Nassauraces once again. Roger Penske returned with his white Grand Sport for what was to be his final week as a professional driver. Although the all aluminum engine performed well during the season, it was replaced with a 364 cubic inch iron block for it's final hurrah at Nassau. The aluminum heads were retained as well as the webers. The iron block was chosen because it flexed less at high RPM, thus allowing the engine to produce more horsepower. The extra horsepower would be needed against the other "no holes barred" racers. The car was further lightened by removing the pneumatic jack system which brought it's weight down to 1900 pounds! Though the lead in the race was initially held by a lightweight Cobra that was powered by a new 390cubic inch all aluminum Ford engine, Roger was able to wear down this Cobra and pass it for the lead and eventually get the checkered flag. Roger took almost a year off from racing after acquiring a Chevrolet dealership earlyin 1965, but he would return, this time as a team owner. Late in '65 he received a phone call from Zora Duntov, telling him that a racing version of the newly introduced 427 cubic inch Mark IV big block engine would be available to select individuals. It was to be called the L-88. Zora promised that he would take care of the homologation papers and Roger soon took delivery of the first production L-88 Corvette. (That story will be told next month). Roger also acquired the last two Grand Sports from Duntovshortly after that. They had been converted to convertibles in an at temptto reduce wind drag at high speed. It was Rogers idea to install the newL-88 into these drag reduced convertibles and race them one more time at Sebring. One Grand Sport was picked, the L-88 was installed, the pneumatic jack system which was used two years earlier, was installed, and larger wheels and tires were installed. Roger felt that this setup would be enough to keep up with the 7 liter Ford Mark II GT40's. Due to the limited preparation time and no track time, only estimates could be made in regards to tire size and spring rates. The aluminum heads on the L-88 were replaced with cast iron versions for the actual race ONLY because these iron heads could be ported much more aggressively than the new aluminum heads. During the'66 Sebring, this Grand Sport did compete competitively with the GT40'sbut it failed to finish after it was forced off the track by a slower car. After the race at Sebring, the other Grand Sport was passed to a friend of Roger Penske's, George Wintersteen. George was able to fine tune the Grand Sport convertible with the proper springs and tires. The aluminum headed L-88 performed quite well also. Unfortunately, the Grand Sport was now without a doubt outclassed by the rapidly evolving Lolas and McLarens that it was forced to compete against. Had the Grand Sport been available in this final form back in 1964, it could have possibly even beaten these mid engine prototypes. The owners of today's Corvettes can thank the individuals involved with these Grand Sports for the technology that they now take for granted. Wide tires, great suspension geometry, all aluminum engines, etc. can all be traced back to 1963, when the Grand Sport underwent it's metamorphosis into a muscular sports racer.
Grand Sport Legend article by: Corvette Legends
