Story and photos by Steve Temple



On the shortlist of the most valuable and significant Corvettes ever built is undoubtedly the ’63 Grand Sport.



Called “The Lightweight,” it is substantially lighter than a factory Corvette, with an ultrathin body and modified chassis. After being fitted with a hot, Weber-carbureted mill, the Grand Sport became virtually unbeatable on the track. For a brief, shining moment at Nassau Speed Week 1963, it proved to be superior to both Shelby’s vaunted Cobra and other GT-class cars and racing prototypes.



Curiously, reproductions of Zora Arkus-Duntov’s remarkable design are not as common as Cobra replicas, even though the Grand Sport was one of the few race cars to ever best Shelby on the track. Superformance is one of the few firms carrying the torch onward, producing a replica that improves on the original, refining a raw-boned racer for the street.



Even though the Superformance Grand Sport has the original’s hard-edged body shape, along with a nearly identical suspension setup, the car is far more substantial and controllable. That’s partly due to the increased weight, estimated at 2,900 pounds when equipped with air conditioning and power-assisted accessories. There’s an increased set on the tires and suspension. Also, the doors don’t feel flimsy, but shut with a firm, solid thunk.



The original Grand Sport’s 377-cubic-inch engine’s output reportedly ranged from 485 to 550 horses (or more, depending on the historical source), but taking things to a higher level is noted engine builder Lingenfelter Performance Engineering, which installed one of its 427-cubic-inch LS7 mills, boasting 592 dyno-proven horses, and offsetting the extra heft of the Superformance.



Drawing on decades of development, the LS7 boasts CNC-ported LS3 cylinder heads, topped by a Holley Dual Quad converted to EFI. Actuating the valve train is a Lingenfelter GT19 bumpstick (227/239 duration at .050 lift - .678/.688 lift). GM rockers, running at 1.8 ratio, are braced with a Comp Cams trunion upgrade. The JE forged-aluminum pistons and Oliver rods sling a Callies DragonSlayer forged-steel crank with a 4-inch stroke and a 11.5 CR.