Turbo Time

Also from Issue 85

  • 2014 Stingray First Drive
  • Tech: C7 Drivetrain
  • Buyer’s Guide: C1/C2
  • 1999 Hardtop
  • Profile: Tadge Juechter
  • 2008 coupe
  • Corvette Racing: Engines
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By not touching certain critical systems and components that directly impacted emissions, most notably the fuel-injection setup and camshaft design, the twin-turbo engine package was able to get through the EPA certification process under rules that did not require small specialty shops to completely recertify an engine that was already certified. This was another benefit realized by turning the turbo program over to a small manufacturer such as Callaway.

Callaway had a certified and production-ready twin-turbo Corvette up and running within a year. The turbocharged engine produced 345 horsepower and 465 lb-ft of torque. Careful sizing of the turbos helped deliver initial boost at just 1,100 rpm and full boost of 10 psi by 2,000 rpm. This created an incredibly broad torque curve that was at least 50-percent greater than the stock L98’s torque output across the entire rpm spectrum. This endowed the engine with incredible flexibility in addition to raw power.

The engine’s enhanced power output required corresponding hardware upgrades. The first four production engines Callaway assembled were built with heavy-duty, four-bolt main bearing Chevy LF5 truck blocks, while subsequent engines were built up using extensively reworked L98 blocks. Low-compression forged-aluminum Cosworth or Mahle pistons spun a forged, gas-nitrided steel crankshaft, while a high-output Melling oil pump ensured adequate lubrication at all times. A dry-sump oiling setup delivered a constant supply of pressurized oil to the turbo bearings, as well as the rest of the engine. Stock aluminum cylinder heads were re-machined and fitted with stainless-steel intake and exhaust valves and stronger valve springs. All machine work was extremely precise and each engine’s entire reciprocating assembly was very carefully balanced to ensure smooth and reliable power through the engine’s entire operating range. The transmission and cooling system were also upgraded to handle the added power and heat output.

In a remarkable move on Chevrolet’s part, the twin-turbo package was given the Regular Production Option code B2K and could be ordered though a select group of authorized Chevrolet dealers. All B2K orders went down the regular assembly line in Bowling Green and were completely assembled with a normally aspirated engine. After completion, however, the cars were shipped to Old Lyme, Connecticut, where the twin-turbo engine installation, as well as the other Callaway-specific modifications, was carried out. Though it was obviously redundant to install engines into cars that would soon have those engines replaced, the procedure allowed the Callaways to be built side-by-side with standard Corvettes without any interruptions or modifications to the normal assembly process in Bowling Green.

The B2K Corvette was unveiled to the media at the Milford Proving Ground during Chevrolet’s 1987 model-year press preview in June 1986. Media members were predictably delighted with the car’s performance. It would sprint from 0 to 60 mph in a scant 4.6 seconds, click off the standing quarter mile in 13 seconds with a trap speed of 108 mph and propel the C4 to a top speed of 178 mph.

When the Callaway twin-turbo package was made available for purchase, potential buyers were equally impressed and reassured by the full factory warranty, but very few had enough disposable income to actually take one home. The option was priced at a whopping $19,995 on top of the cost of the car, which was $27,999 for a coupe and $33,172 for a convertible during the 1987 model year.

Our feature car is #81 of the 184 twin-turbos built in 1987. In addition to the turbo package, it features a number of other options, including RPO-code FG3 Delco-Bilstein shocks ($189) and aftermarket 17-inch Dymag magnesium wheels, which were extra cost in ’87 but standard on B2K Corvettes in subsequent years. It was sold

new in Colorado to a man from Detroit, and came into the possession of the second and present owner, noted Callaway collector Tony Cardiello, in 2005.

Cardiello first spotted a B2K at his local Chevrolet dealer in 1987. “I really liked what I saw, but the price tag didn’t seem to make much sense at the time,” says Cardiello. “The Callaway option almost doubled the price of the car!”

Though he couldn’t pull the trigger in 1987, Cardiello’s mind was set in motion. He began researching Reeves Callaway and the cars his company built; the more he read the more he wanted one of them. “When I understood what made Callaway’s cars so special, I was thoroughly impressed,” says Cardiello. In 1991, he bought one—a ’91 CR-1, which was based on the C4 ZR-1.

Cardiello subsequently added a 1995 Callaway Impala SS, a ’98 Callaway Commemorative Edition Camaro, the Bright Red ’87 B2K shown here and, most recently, a 2012 Cyber Gray 25th Anniversary B2K Corvette. Of them all, the ’87 holds a special place in Cardiello’s heart: “It’s the Corvette that started the Callaway legacy more than a quarter century ago, and it’s the car that initiated my interest in Callaway.”

Cardiello regularly participates in rallies and car shows staged by the Long Island Corvette Owners Association, and says he still gets a big thrill from driving his ’87 B2K: “The whoosh of the turbos when I nail it always brings a smile to my face.”