Golden Jubilee of Mid-Engined Corvettes

April 30, 2010
Blame it all on Corvette patron saint Zora Arkus-Duntov. Roughly half-way through his too-short 21 years at GM, Arkus-Duntov concluded that a mid-engined Corvette was the ideal way to keep performance on an upward swing. His experiments and project cars investigating that approach should have paved the way to a production model with the engine positioned closer to the drive wheels. Unfortunately, when Arkus-Duntov retired at the end of 1974, most of the passion for the mid-engined Corvette departed with him. While successive chief engineers have periodically toyed with the idea, none have succeeded in aligning the necessary technology with a business case and corporate politics.
1004 06+chevrolet Corvette Cerv I+front Three Quarter View
Join with us now as we traipse the long and winding road of mid-engined Corvette milestones. What better time than 50 years after Arkus-Duntov risked his career playing with a single-seat experimental racer that bore little resemblance to production Corvettes?
CERV 1 The idea of moving the engine behind the cockpit entered Arkus-Duntov's fertile imagination at Sebring in 1957 when the hastily prepared Corvette SS sports racer parboiled driver John Fitch's feet. Were it not for a failed suspension bushing after 23 laps of the 5.2-mile airport course, Fitch may not be walking today. Instead of lining the magnesium bodywork with insulation to block the engine and exhaust heat, Arkus-Duntov shrewdly concluded that the wiser solution would be to relocate the furnace...away from the driver.
Work began on a project car to study the feasibility of a mid-engine layout. Strictly speaking, the resulting Chevrolet Experimental Racing Vehicle (CERV) was not a Corvette. But the fact that this car pioneered the independent rear suspension that did make production for the 1963 model year establishes a clear lineage between the racer and the road car.
CERV was constructed with a steel-tubing space frame supporting two lateral fuel cells, a fuel-injected 4.6-liter (283 cubic inch) mostly aluminum V-8, and a four-speed transaxle. Sandwiching the gearbox between the engine and a Halibrand differential moved the driver's seat well forward in the 96-inch-long wheelbase. Sixty percent of the car's 1450-pound dry weight rested on the rear wheels. With 353 horsepower on tap, CERV's performance was exemplary.
Arkus-Duntov aspired to campaign CERV at Indianapolis if and when GM dropped its ban on direct racing involvement. In the fall of 1960, the car demonstrated competitive speed climbing Pikes Peak. Following limited race track tuning, it made a few demonstration laps before the US Grand Prix at Riverside, California. That prompted a name change - from Racing to Research - as a nod to GM's no-racing edict. To close out the CERV 1 era in a memorable way, Arkus-Duntov installed a 6.2-liter small-block V-8 and toured the five-mile circular track in Milford, Michigan, at 206 mph.
CERV I was donated to the Briggs Cunningham Automotive Museum in 1972. It's currently owned by Corvette enthusiast Mike Yager and is available for inspection at his My Garage museum in Effingham, Illinois.
CERV II Lessons learned, Arkus-Duntov's next research vehicle moved a worthwhile step in the Corvette direction. With sights set on world endurance racing - specifically LeMans and Sebring - work commenced in 1962 on a mid-engined sports roadster. This time mad Russian's thinking was an order of magnitude bolder: the car coded XP-817 and later CERV II had a monocoque chassis with a mid-mounted engine and all-wheel drive. Two compact transaxles energized the low-profile tires and a driver-controlled rear spoiler aided high-speed stability. With a 6.2-liter small-block providing power, this prototype would theoretically accelerate to sixty mph in 2.8 seconds on its way to a stable 214-mph top speed. Unfortunately the dual-transmission arrangement wasn't reliable and GM officials chose Jim Hall's Chaparral effort to fly the flag in international sports car racing over Arkus-Duntov's creation.
1004 07+chevrolet Corvette Cerv Ii+front Three Quarter View
CERV II was also donated to the Cunningham museum and may now be housed at the private Collier Automotive Museum in Naples, Florida.
ASTRO II XP-880 After experimenting with two rear-engined design studies - the 1967 Corvair-based Astro I and the ill-conceived XP-819 V-8-powered prototype - various departments within the GM hierarchy finally settled on mid-engined sports cars as the most appropriate platform for advanced engineering. This set in motion a 'mine's better' intramural competition that bore major show-car fruit.
1004 02+1968 Chevrolet Astro II XP 880 Concept Car+profile
In 1967, Frank Winchell's creative R+D staff cooked up a serious response to Ford's impressive GT40 program. The XP-880 was a beautiful two-seat coupe draped over an X-shaped steel backbone frame. Fuel was carried centrally in a well-guarded rubber bladder and the engine's radiator was located at the rear to avoid heating the cockpit or lifting the front end. A 390-horsepower big-block V-8 provided go through a lowly Pontiac Tempest two-speed automatic transaxle.
Painted metallic blue and christened Astro II, this still-born experimental Corvette was shown to a wide-eyed public at the 1968 New York auto show. Today it resides at the GM Heritage Center.
XP-882 Arkus-Duntov didn't take the XP-880 attack on his Corvette castle lying down. While tests on Winchell's challenger were underway, Arkus-Duntov's crew conceived a car that would take full advantage of knowledge gained from his CERV II project.
1004 03+1970 Chevrolet Corvette XP 882 Concept+side View
Arkus-Duntov's brainstorm was to mount the engine sideways in the car so that existing transmission and axle components could be used. The small-block V-8 and a choice of manual or automatic transmissions fit neatly in a 95.5-inch wheelbase. The most clever subtlety of the layout patented by Arkus-Duntov was the ease with which drive to the front wheels could be added.
Two test cars were finished by the spring of 1969. Unfortunately, the timing was horrible. GM was suffering a long labor strike, Corvette marketing geniuses fretted that a mid-engine car might not appeal to faithful customers, and there was a new sheriff in town: John DeLorean had just taken over the Chevrolet general manager's role. To Arkus-Duntov's chagrin, DeLorean gave XP-882 a firm thumbs down.
That didn't thwart other forces within GM from exploiting the striking mid-engine prototype for their ends. Fearing Ford and AMC presentations scheduled for the 1970 New York auto show, GM design boss Bill Mitchell had XP-882 painted a metallic silver to serve as a show stopper. That move worked as intended and a rabid public clamored for more. In response to this enthusiasm, DeLorean approved the next generation of mid-engined Corvette experimentation.
Vaguely aware of these corporate machinations, Road & Track presented XP-882 as its January 1971 cover subject with an unequivocal, "This is the New Corvette" announcement.
XP-895 DeLorean's engineering background and broad base of influential contacts proved instrumental in moving the mid-engined Corvette idea another major step forward. The Reynolds Metals Company was persuaded to craft an aluminum body to explore how much weight could be saved.
1004 01+1973 Chevrolet Corvette XP 895 Reynolds Aluminum+front Three Quarter View
With a driveline carried over from XP-882, the finished spot-welded and adhesive-bonded aluminum prototype weighed about 3000 pounds, a savings of 450 pounds over a steel-bodied car.
This time around, the red light was cost. The extra expense of aluminum over steel or fiberglass would drive the price of a Corvette beyond the reach of its traditional customers. Soliciting bids from European suppliers was also tried to no avail.
Stored out-of-doors for years, the cast-aside XP-895 prototype was eventually rescued and refurbished to become an admired member of GM's heritage collection.
TWO-ROTOR XP-987 Originally planned as a successor to the Opel GT, the Corvette 2-Rotor show car was an expeditiously rebodied and repowered Porsche 914. An attractive GM-designed two-place coupe body was constructed by Pininfarina in a mere three months. In the fall of 1973, this stunning red prototype appeared at the Frankfurt auto show to herald GM's profound interest in Wankel rotary engines.
1004 04+1973 Chevrolet XP 897GT 2 Rotor+side View
The smooth rotary powerplant developed 180 horsepower at 6100 rpm and redlined at 8500 rpm. Teamed with a 2600 pound curb weight, the engine delivered acceptable but not sparkling performance. Predictably, Arkus-Duntov had a more creative solution in mind.
After its show car service ended, the Corvette 2-rotor was rescued from the crusher by Tom Falconer, a British car collector.
FOUR-ROTOR In 1972, under Arkus-Duntov's direction, GM engineer Gib Hufstader crammed a pair of rotary engines into XP-882's engine bay. That package constituted the largest Wankel ever installed in an automobile; the estimated output was 350 hp at 7000 rpm.
1004 05+aerovette+front Three Quarter View
GM's design staff contributed one of the most spectacular wrappers to ever wear a Corvette nameplate. The windshield was creased along its centerline and canted back a steep 72 degrees. The radically low and pointed nose was accompanied by a sharp, sleek tail. The gull-wing doors gracefully folded as they opened to provide easy reach in the raised position.
Presented with the 2-Rotor, the remarkable 4-Rotor Corvette made its debut at the 1973 Paris Salon. Just over a year later, a fastidiously crafted scale model of the car was presented to Arkus-Duntov as a retirement gift. During a visit to his home years later, Arkus-Duntov pointed to his treasure and announced that the 4-Rotor was his all-time favorite Corvette.
Even before Arkus-Duntov's departure, GM's entire rotary engine program had been shelved. To keep the much loved gull wing design flying for a few more years, the two rotaries were plucked from the engine bay and replaced by a conventional small-block V-8. Renamed Aerovette, this prototype is currently in the GM heritage collection.
GTP Eventually, GM did get around to racing a mid-engined Corvette. Collaborating with Lola Cars International, the General campaigned cars with a vague family resemblance to production Corvettes in IMSA's GTP (grand touring prototype) class for five seasons commencing in 1984. The first T710-chassis racers were powered by turbocharged 3.4-liter V-6 engines followed by T711 models fitted with 5.7-liter normally-aspirated V-8s. For 1986, a T86/10 Lola chassis reverted to 3.0-liter turbo V-6 engines. In 1987, Lotus provided the effort an active suspension system which was used (unsuccessfully) in just one race. V-8s became the preferred power source at the end of the 1987 season. A total of seven Corvette GTP racers were built and two wins were earned in 1986. Plans to race at LeMans never reached fruition.
1004 09+chevrolet Corvette GTP+front Three Quarter View
GM's Heritage Center currently has 1984 and 1986 vintage GTP racers in its collection.
INDY, CERV III Even though the chinks were beginning to form in its armor, GM in the mid-1980s was technically at the top of its game. The addition of Hughes Electronics and Group Lotus as GM subsidiaries greatly expanded concept car possibilities. Collaboration with Ilmor Engineering yielded a competitive Indy car V-8.
1004 08+chevrolet Corvette Cerv Iii+front Three Quarter View
The Corvette Indy concept GM displayed at the 1986 Detroit auto show joined these sprawling interests into one arrow pointing towards an auspicious future. Indy's composite-plastic structure supported a twin-turbo 2.6-liter V-8 producing 600 horsepower. The list of advanced features sounds like a spec sheet from the latest Porsche production model: electronically controlled four-wheel drive, four-wheel steering, active suspension, and by-wire throttle control. Car and Driver's Corvette Indy report concluded, "The next-generation production car will almost definitely be a wild-looking, mid-engine design."
Four years later, that was definitely not the case but GM trotted out the same basic concept car wearing a familiar sounding Corporate Experimental Research Vehicle (CERV III) nameplate. Additions included ultralight body panels, carbon-carbon brakes, and a twin-turbocharged twin-turbocharged 5.7-liter LT5 V-8 delivering 650 horsepower. Claimed performance - 0-60mph in 3.9 seconds, a 225 mph top speed - accurately anticipated today's Corvette ZR1.
Offers to the press to test drive the Indy/CERV III concept car were never fulfilled. Today a resin mockup of the Indy show car and a functional CERV III are parked in peaceful repose at the GM Heritage center.
2007 C7 ENGINEERING PROGRAM The current Corvette engineering team spent most of 2007 designing a mid-engined replacement for their aging C6 sports car. Prompted by an expected change in endurance racing rules aimed at reduced speeds at LeMans, someone was bold enough to suggest merging C7 and C7R efforts to use V-8 engines located where god and Enzo Ferrari intended them to live.
1004 10+chevrolet Corvette C7+front Three Quarter View
It's safe to assume that this C7 would have been smaller, lighter, and far more fuel efficient than today's Corvette to help meet more stringent CAFÉ requirements. Exactly how that would be achieved without a steep rise in list price is unknown. GM's stillborn diesel V-8 was even mentioned as one of the engine candidates.
Unfortunately, the most recent attempt to build a mid-engined Corvette ceased before the clock struck 2008. The exact reasons why were never revealed. The insurmountable hurdle could have been the cost associated with one or more transaxles unique to this relatively-low-volume car line.
So, like every Corvette from the dawn of time, the C7 edition will undeniably honor the classic front-engined tradition. But hope springs eternal. At least one rumor monger suggests that GM is seriously considering an expansion of the Corvette family to include a few $100,000+ versions with the engine snuggled in close proximity to the rear wheels. If the planets finally do align, the mid-engined C8 Corvette would arrive late in the current decade.

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