A mid-engine Corvette with rotary power – the 1973 XP-897 GT concept
Built atop a shortened Porsche 914/6 chassis, fitted with a steel body designed by GM but crafted by Pininfarina, and powered by a GM two-rotor engine mounted amidships, the 1973 Chevrolet Corvette XP-897 GT concept hinted at a future that might have been – but never was – for America’s sports car. Rescued from the crusher by British Corvette enthusiast and author Tom Falconer, this evolutionary dead end made a rare North American appearance at the 2019 Amelia Island Concours d’Elegance, taking place on Sunday, March 10, at The Ritz-Carlton on Amelia Island, Florida.
In the early 1970s, GM, Ford, Chrysler and AMC all looked to the Wankel rotary as the engine of the future. It was significantly smaller and lighter than piston-equipped equivalents, and with fewer internal components, easier and cheaper to build. German automaker NSU had been developing the design for years, and the belief among domestic automakers was that any remaining engineering obstacles could be easily overcome with their immense resources. Among U.S. companies, GM in particular embraced a future where the Rotary Combustion Engine (RCE) would power everything from economy cars, like the Chevrolet Vega, to performance cars, like the Corvette.
Credit – or blame, depending upon one’s perspective – goes to Ed Cole. In The Complete Book of Corvette – Every Model Since 1953, author Mike Mueller cites a 1980 AutoWeek interview with Zora Arkus Duntov, where Duntov recalls, “Ed Cole was enamored with the Wankel engine, and he kept twisting my arm. ‘What about a rotary Corvette?’”
The RCE was already under development for use in the next-generation Chevrolet Vega, which was slated to get a two-rotor engine displacing 266-cu.in. and rated at 180 horsepower. Approval was given to construct a Corvette concept using this engine as well, and the decision to make the car mid-engine was not an attempt to improve handling, but rather a means to economize packaging. As Mark Hales wrote for Drive-My.com, GM was developing a two-rotor engine and transmission for a front-drive platform, and this compact layout could easily be adapted to a mid-engine, rear-drive car – like the Corvette concept.
To increase the car’s appeal in global markets, the decision was made to downsize this Corvette concept, which would also save weight and increase the performance of the two-rotor RCE. Without a suitable platform in-house, GM looked to Europe for a mid-engine car of roughly the right size, opting to purchase a Porsche 914/6 for the project. Even this wasn’t small enough, and GM reportedly cut 6.5-inches from the Porsche’s wheelbase before widening the track in front and rear. The stock Porsche suspension was retained (with altered mounting points to accommodate the widened track), as were the original brakes, and the platform was fitted with the RCE (mated to three-speed automatic transmission) before being sent to Pininfarina for the body.
The finished product was dubbed the XP-897 GT, or alternatively, the Two-Rotor Corvette, and its official debut came at the Paris Motor Show in October 1973. Shortly after, another rotary-powered Corvette appeared on the show circuit as well – built atop the XP-882 platform, this larger variant featured a four-rotor engine (essentially two RCEs bolted together), tuned to produce a reported 420 horsepower. Car and Driver called the four-rotor XP-895 concept “the betting-man’s choice to replace the Stingray.”
Both RCE-powered Corvettes made the rounds at car shows across the globe through the summer of 1974. Then, in September, Cole pulled the plug on GM’s involvement with the rotary engine, citing difficulties in getting it emissions-certified. Yes, more stringent emissions requirements would have complicated the further development of the RCE, but the reals reason was this: In the wake of the 1973 oil crisis, fuel economy became a legitimate concern for buyers. Even if rotary engines could pass more stringent federal emissions requirements, making them less thirsty posed an entirely new set of challenges.
Returning XP-897 GT to the United States posed an issue, since the duty paid to import the car from Pininfarina in Italy was for temporary display only. To avoid paying additional taxes, GM pulled the RCE and transmission, then crated up the concept and stored it at Vauxhall’s Design Center in England. For about a decade, the Corvette concept was largely forgotten, until a remodeling of the facility brought it back into the light and plans were made to send the XP-897 GT to the crusher.
Fate intervened when Falconer received a tip that the car was bound for destruction. Determined to save it, he phoned the head of GM Design, Chuck Jordan, and asked for his assistance in obtaining permission to purchase the concept. He agreed, a deal was reached, and the XP-897 GT – sans drivetrain – was delivered to Falconer’s garage instead of the scrapyard. To put the car back on the road, he temporarily installed a four-cylinder engine and automatic transmission from a donor Vauxhall Cavalier, but later replaced this with a truer-to-concept two-rotor Mazda 13B rotary engine, still mated to the automatic.
That might have been the end of the story, except for Falconer’s persistence. When GM abandoned development of the RCE program, it looked to put as much distance as possible between itself and the ill-fated rotary engine as possible. Most examples were collected and scrapped, with one notable exception remaining on display in the Ypsilanti Automotive Heritage Museum. Against the odds, Falconer managed to locate another, patiently negotiating a purchase price with its owner over several years. This engine will be displayed alongside the Corvette XP-897 GT at Amelia Island, both telling the story of a future that may have existed – for both GM and the Corvette – in an alternate timeline.
Source: https://www.hemmings.com/blog/2019/0...97-gt-concept/
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