Callaway Twin-Turbos

Throughout its evolution, the gutsy, lusty Corvette symbolized power and speed. But, in its second decade, a number of factors conspired to place limits on just how fast it could go and what records it could claim.

In the 1950s and for most of the 1960s, Corvettes were raced competitively, setting standards on the SCCA and other circuits around the country. Adding to that image of power and speed was the introduction of "big block" engines -- the 427ci in 1966 and the 454ci in 1969.

But as the 1970s dawned, federally-mandated restrictions were imposed on emissions and efficiency. These rules clashed with the public's desire for horsepower and speed. With the imposition of clean air standards, compression ratios were lowered to accommodate lower octane fuels and horsepower was determined not by "gross" but by "net" ratings systems.

Then, in 1973, America's fuel supplies were severely impacted by the Arab oil embargo. Additionally, soaring insurance rates were making the ownership of high-powered models prohibitive. Consequently, the last of Corvette's big block engines were mounted on 1974 models.

As the decade of the 70s drew to a close, even stricter state and federal passenger safety, fuel efficiency and emissions standards were enacted. When Corvette's fourth generation platform was introduced in 1984, company engineers factored-in these government stipulations. When they brought their newest version to market, it was completely redesigned in almost every respect. However, for the true Corvette aficionado, the urge for raw power was never very far beneath the surface.

In 1986, in cooperation with a New Jersey dealer, 50 commemorative models were built in a special arrangement honoring the dealership's founder. One of these specially-painted, silver beige-over-black coupes was retrofit with a twin-turbo engine built by Callaway.

Callaway Cars, Inc. of Old Lyme, Connecticut, had been designing and building aftermarket turbo modifications for a number of foreign cars over the preceding decade. While General Motors and its Chevrolet Division did not enter into a formal agreement with Callaway, it did make the special option package available through its network of dealerships.

Although not a factory-installed option, it could be ordered in advance from Chevy dealers. Fully assembled Corvettes with 350ci blocks were shipped from Corvette's Bowling Green, Kentucky factory to Callaway Engineering in Connecticut for engine conversion. Other component modifications contributed to improvements in handling, braking and reliability.

Of the 184 twin-turbos built in 1987 at an additional cost of $19,995, 63 were convertibles and 121 were coupes. The special engine generated 345 horsepower and is reputed to have reached a top speed of 177mph with overdrive gearing. All Callaways had manual transmissions and none were certified for sale in California.

The Callaway option for Corvette's was short-lived, lasting only until 1991. During those five years, a total of 497 twin-turbos were sold.

At the time, the Callaway/Corvette conversion offered the enthusiast the fastest "production" car available in this country. It's estimated that over 300 of those special modifications are still roaring down roads and tearing up tracks somewhere in the world today.

But, back in the late 80s, Corvette was developing its own high-performance answer to the twin-turbo -- the ZR-1 which was introduced to the motoring public in 1990. Dubbed "The King of the Hill," it was "bi-modal," meaning it could be used for street driving or, on demand, converted to a race car with all the necessary speed and handling.

Thus, the powerful Corvette/Callaway conversion phased out of existence.