Corvette Evolution, Part 10: The C4 Corvette that Wanted to be a Supercar

Corvette Evolution

Since 1990, the ZR-1 was a challenger to the established European supercars.

During the first three decades of its existence, the Corvette established its reputation as the first and only American sports car. Below this level there was a crowded playing field for pony cars and above it there was the rarified layer of the supercars heavily populated by European brands. In the 1980s, Corvette management took on a new challenge: to build a Corvette that could penetrate that exclusive club of supercars like the Porsche 928GT and Ferrari Testarossa.

But even in its new 'supercar' guise, that would be called ZR-1, the Corvette was supposed to cost its owners just over $50,000. Starting in 1984, the R&D project lasted for a few years under the nickname '400 horsepower package'. Engineers were mainly interested in implanting an all-powerful turbo-charged motor under the hood to bestow on the car a new speed dimension, during an era dominated by turbo engines and new digital management systems. 15 test mules were built, engines were tested, but when push came to shove, the marketing department advised that the turbo trend was fading out.

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The 'Turbovette' was out; another solution was needed and it arrived from across the pond. David McLellan, Corvette Chief Engineer, asked Lotus Group to develop a set of dual-overhead camshaft cylinder heads for the existing 5.7-liter small-block V8. However Tony Rudd, Lotus chief engineer, proposed to build a new engine. Surprisingly the idea was approved by Chevrolet management and even a detailed explanation was given: "To create a car that is second to none in acceleration, nothing less than the fastest production car in the world," explained Chevrolet Chief Engineer, Fred Schaafsma.

"Achieve that kind of performance without sacrificing drivability, not only at the high end, where you expect fast cars to drive well, but at the low end, too. Then package all this leading-edge performance and drivability into an engine that could still deliver great fuel economy. Design this engine to fit between the rails of the existing Corvette's engine compartment, a brand new engine but not one that would require a totally new car." The result was the LT5, a European designed engine based on relatively modern racing technology, for the first American supercar.

The LT5 was a 5.75-liter all-aluminum V8 engine, that although technologically had nothing to do with the small-block family, it shared the family's iconic dimension of a 4.40 inch bore center-to-center distance. However, the crucial components were a 4-valve per cylinder engine head operated by two overhead camshafts. Engine production was contracted out to Mercury Marine, a marine engine manufacturer (whose small two stroke outboard engines were also used in motor racing during the 1950s). Mercury was chosen because of its expertise in aluminum processing and the low production run of a maximum of 50 engines that was envisaged.

The facility built for the LT5's production was equipped with cutting edge CNC equipment and the engines were hand-made, just like racing engines. Changes were made to the car all around in order to adapt it to the 32 valve 375hp and 370 lb-ft V8. This included Goodyear Eagle Gatorback 315/35ZR-17 tires mounted on 11-inch-wide rims and a wider body that necessitated new doors, rear quarter panels, and a rear bumper fascia with a new rectangular lamp design. The new Corvette supercar was unveiled at the 1989 Geneva Motor Show and received a roaring welcome from the world press.

Production began a year later and buyers received not only an owner's manual, but also a driver's manual that provided valuable advice on how to get the most performance in the safest manner from the 4.6 seconds to 62 mph and 180 mph top speed American supercar.

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