No automotive enthusiast can dispute the contributions of Zora Arkus-Duntov to the development of the Corvette. He was relentless in his efforts to improve the breed, even in his later years after a mandatory retirement in 1975. So when Bob Schuller of American Custom Industries (ACI), a company known for its replacement Corvette body panels, approached him in the late ’70s about putting his name on a highly stylized convertible version of the 1980 production model, he insisted on one key item: turbocharging.
No surprise there, considering how lackluster the base L48’s engine output had become during that power-starved era. The 350-ci mill delivered less than 200 horses, and even worse, you could only get 305 cubes in a California-spec car. It must have pained Duntov to see how his glorious performance machine had been become so ignominiously down-rated. Something had to be done, and he was the man to do it. But not without first overcoming some serious technical hurdles.
Packaging, for one thing. Engine-bay space was scant, so a new hood had to be fitted for extra clearance (along with several other body mods, as we’ll see). As for the engine’s innards, emissions laws prevented “cracking the chest,” so that left only the option of forced induction. With the carburetor in the factory location, Duntov drew on his formidable engineering skills to build an innovative intake manifold that fed the air/fuel mix into a turbocharger, and then back to the cylinder heads. No intercooler was needed, since this draw-through turbo setup kept fuel suspended in the mixture, thus preventing detonation. Even so, this configuration did have some other issues, such as a lot of turbo lag.
In addition, due to the constricted space, the engine bay became a heat sink, causing the rubber hoses to melt. Switching to braided hoses for plumbing the radiator, oil return, air conditioner, and fuel system alleviated this issue, along with additional air venting. A special air cleaner with vents on its upper side topped off the engine.
Once the overheating problem was addressed, Duntov had managed to add about 70 horsepower via 4 to 7 psi of turbo boost (estimates vary). Not an exuberant output figure, especially by his lofty standards, but certainly better than leaving the engine in factory trim. As the car’s original ACI brochure put it, “[T]he limited-edition Duntov car delivers the kind of get-up-and-go that has been gone in recent years.”
This overheating issue actually was a familiar one for Duntov. And it relates to an anecdote from this particular car’s owner, Greg Heinrich, who has a large collection of rare and desirable Corvettes (sidebar). Heinrich’s father, Bill, who ran the Las Vegas Chevy dealership where Greg is now CEO, would assist Duntov with parts such as radiators for big-block engines when he came through town to perform hot-weather testing in Death Valley. They got to be pretty good friends, and Duntov shared his excitement about building the new turbocharged cars that bore his name. The feeling was contagious, and Bill Heinrich ended up purchasing one brand new.
Today, the Duntov Turbo is one of the more distinctive and popular Corvettes in Greg Heinrich’s collection, one that draws considerable attention from local TV shows and car clubs on scheduled tours. What makes it such a standout in a collection of far more valuable Corvettes?
Despite all the technical difficulties and underwhelming power output, in modern hindsight the Duntov Turbo was actually a praiseworthy effort blessed with an alluring shape. While some folks thought it a bit extreme at the time, the form holds up well and looks striking. By comparison, we’ve come across many far more outlandish Corvette-based body configurations, and this one, while steroidal in some ways, exhibits suitable restraint.
Quoting again from the ACI brochure, “The body of the car retains just enough of the current production car’s styling to show you that it’s a Corvette, yet one can see that the Duntov Turbo exterior is truly that of a ‘special edition’ motor car.”
Of course, it helped that GM had stopped building Corvette convertibles after 1975, making the Duntov Turbo one of the few available options for topless motoring in a muscle car. Rather than attempting to reinvent the wheel here, ACI wisely employed the same frame and cowl reinforcements used on topless Corvettes from the mid-1970s.
Drawing some inspiration from John Greenwood’s wild, wide-body racecars (also built by ACI), the panels on the Duntov Turbo increased width by six inches over that of a stock Corvette. Skillful sculpting on the taller hood and rear bumper, along with additional vents and recessed, rectangular single headlights, created a distinctive and compelling configuration.
All of the Duntov Turbos were finished in white with a red interior, an obvious homage to the original ’53 Corvette that helped launch Duntov’s lifelong affair with the brand. But for a more modern flair, the cockpit featured a boost gauge and red digital secondary gauges, along with every available power option. Also included was the otherwise rare factory AM/FM/CB radio made popular by trucking culture of the late ’70s.
Yet this interior treatment is one area where Greg Heinrich feels the car really shows its age. Upholstered in “mouse fur” and trimmed with leather, it hearkens back to the excesses of the disco scene of the late ’70s. Even the dashboard has a fuzzy texture, rather than smooth metal or a carbon-fiber overlay.
“The exterior of the car very nice, and the wheel choice is good,” Heinrich allows. “[But] the interior is not its strong point, and reflects the era.” Describing it as akin to the custom Vette in the movie Corvette Summer, he feels the cabin look is “a little garish and ‘out there.’”
Moving beyond that aesthetic misstep reveals more innovation, such as the specially tuned Bilstein shocks Duntov specified for the car. Such an upgrade was long overdue, as the C3 chassis was seriously dated, mostly unchanged since 1963. Also, each Duntov Turbo was upgraded with a reworked recirculating-ball steering system that provided improved feedback, along with 15-inch modular Weld wheels wrapped in Goodyear Wingfoot tires (255/60s in the front and 265/60s in the rear).
The original rubber is still on the car but has virtually ossified over time, so it squealed excessively during a short drive around the Fairway Chevy dealership. (Understandably, Heinrich was reluctant to let us venture out very far in this historically significant gem.) Cornering grip could best be described as “greasy.”
As for the turbo, it doesn’t kick in right away, and with only a three-speed automatic available, you have to stomp on the go-pedal to force a downshift while waiting for the boost to spool. Such is the delay inherent to a draw-through turbo configuration. Changing the torque converter, or the 3.07:1 ratio of the differential gears, would add some alacrity, but back in the day such modifications would have elicited unwanted attention from the ever-vigilant EPA.
The Duntov Turbo garnered an altogether different level of attention from the buying public. The base price of $30,000 was about twice as much as what a base-model Corvette sold for in 1980. And while Zora Duntov’s nameplate on a Corvette was worth a lot to some buyers, it wasn’t enough to ensure widespread appeal. Initially the production goal was 201 units, but the actual run never even came close to that. Estimates put the total anywhere from a low of 32 to as high as 86 cars built.
Interestingly, Duntov could not receive his own car until 100 were sold, due to a provision in his contract with ACI. And even if he had, his wife Elfi would not have been all that pleased with it. According to comments she made to Heinrich at a Bloomington Gold event following Zora’s passing, she expected the car to have a big-block engine. Her preference isn’t surprising, since that was the powerplant installed in a customized ’74 model given to Duntov as a retirement gift. (Look for a story on this special C3 in an upcoming issue.)
So while the Duntov Turbo can’t be considered a triumph in the traditional sense, it serves as evidence that the “Father of the Corvette” never flagged in his efforts to improve the breed. In hindsight, some people’s shortfalls far surpass others’ successes. m