The Grand Sport Corvette Legend

Corvette Racing Legends, The Story of the L-88 Option Package
is available now. Click Here to go to Corvette Racing Legends.com

I've included many color photos and other previously unpublished photos
of the Corvette Grand Sports in my book Corvette Racing Legends.

2010 Corvette Grand Sport info (click here)

The Grand Sport Corvette made its first appearanceearly in the 1963 season in the C-Modified class with a production 360 HP 327 Fl engine in its lightened 2000 pound body. It raced the season as a "stock" appearing racer. The season finale was held at Nassau each year with a "no holds 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 otherwise banned from regular club racing.




When the Grand Sport Corvette made its 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 of the Grand Sport Corvette 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 aluminum 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 Corvette is letter "F" in the series.




These all aluminum engines were shared with Jim Hall's Chaparral, but his sports racers used smaller 48mm webers that were more suited to the RPM requirements of the unique automatic transmissions that were in these revolutionary racing cars.

The Grand Sport Corvettes 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 1964 12 hours of Sebring.

All three Grand Sport Corvettes entered the 1964 12 Hours of Sebring.




Roger Penske and Jim Hall shared a newly painted white Grand Sport Corvette. 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 of the Grand Sport Corvette. The attention to detail paid off, for this Grand Sport Corvette finished 1st in its class! The '64 season ended with the Nassau races once again.

Roger Penske returned with his white Grand Sport Corvette 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 its 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 holds barred" racers.


The Grand Sport Corvette 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 390 cubic inch all aluminum Ford engine, Roger was able to wear down that Cobra, pass it for the lead, and eventually get the checkered flag.


Roger took almost a year off from racing after acquiring a Chevrolet dealership early in 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 inchMark 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. Roger also acquired the last two Grand Sport Corvettes from Duntov shortly after that. They had been converted to convertibles as a test to reduce lift and wind drag at high speed. It was Rogers idea to install the new L-88 into these drag reduced Grand Sport roadsters and race them one more time at the 12 Hours of Sebring 1966.


One Grand Sport Corvette 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 testing 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, thus creating more horsepower. During the '66 Sebring, this Grand Sport Corvette did compete competitively with the GT40's but it failed to finish after it was forced off the track by a slower car.

 

After the race at Sebring, the other Grand Sport

Corvette was passed to a friend of Roger Penske,

George Wintersteen. George was able to fine tune

the Grand Sport roadster with the proper

springs and tires. The aluminum headed L-88

performed quite well also.


Unfortunately, the Grand Sport Corvette 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 the Grand Sport Corvettes 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.


2010 Corvette Grand Sport info (click here)

L88 Racing ZL1 Corvette Mako Shark Greenwood Corvettes
Corvette Home Yenko Corvette L88 Corvette Grand Sport Corvette

Click on the Corvette links for more Corvette stuff.

 

 

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