The 9 Mid-Engine Corvette Concepts That Didn’t Make it To Production
All of these prototypes paved the way for the upcoming C8by Michael Fira, on
For over five decades we’ve been teased with various Corvette concepts displaying the idea that the engine should be moved from just in front of the cabin to behind the rear seats. While this idea might seem ludicrous to purists, we know that it will finally become a reality with the forthcoming C8. But there wouldn’t have been a C8 without all the prototypes that preceded it.
If everything we’ve seen and heard in the past couple of years regarding the 8th generation of the Chevrolet Corvette is true, and there’s little doubt about it, the C7 will become the final front-engined Corvette because the C8 is bound to have the engine where rivaling Lamborghinis and Ferraris have had it since forever - behind the front seats. A few camouflaged prototypes have been seen testing over the past few months and, while we aren’t sure about its name, we know that it’ll be based on a new platform and it will cost a whole lot more than the current model.
The best view we’ve got of the new Chevrolet sports car is of a mule testing at the Nurburgring-Nordschleife in Germany. It features a radically different design although some design cues from the current model, like the side air vents up front, remain. We don’t know what engine will power the new car, pundits reporting that a racing version seen testing at Road America might sport a V-6, and we might not get much more insight on it until next year’s Detroit Auto Show where, supposedly, Chevy will take the wraps off the new model. Until then, here’s a look at the plethora of prototypes that predated it.
The C8’s bloodline stretches over five decades into the past
The Chevrolet Corvette, often called 'America's Sportscar', has been front-engined ever since it was launched back in 1953.
However, GM skunkworks has been toying with the idea of a mid-engined ’Vette for almost just as long. Budget restraints, problems with manufacturing and the 2008 recession saw the plans for a mid-engined Corvette find their way to the bin. But, now, it seems that GM is done playing games and we will get a Chevy-badged sports car with the engine in the middle ready to challenge a Porsche 911 Turbo or others alike.
According to Road & Track, "in 2004, it was decided that the Corvette had reached the limit of grip with the traditional front engine, rear-wheel-drive layout." Apparently, at the time, two full-size clay models were built to test the idea of a new Corvette and a Cadillac sports car with the engine behind the passengers.
That was the last time when Chevrolet was this close to changing the architecture of its flagship model but now Mark Reuss, the man at the helm of GM Global Product development, says that the C8 will be "revolutionary." We all know what that means. It means that the cars you’ll read about below will have a production counterpart.
1964 Cerv II
The CERV II, or Chevrolet Engineering Research Vehicle II, wasn’t a Corvette per se. However, it did use the all-aluminum pushrod 6.2-liter small block V-8 that made its way in the 1963 Corvette Grand Sport. The CERV II should’ve been part of a six-car run meant to showcase GM’s technological prowess in the early ’60s. But, then, GM banned works racing and the sole prototype built was only allowed to take part in a few useless demo runs after the project was canned.
This unique car features an open-top bodywork designed by Larry Shinoda and Tom Lapine.
The bodywork seats on a monocoque chassis which wraps nicely around the mid-mounted 500 horsepower engine.
With Le Mans-style gearing the CERV II achieved speeds in excess of 212 mph while a 0 to 60 mph acceleration time of under 3 seconds was possible with a sprint setup. The car later received a 7.0-liter ZL1 engine which offered even more power.
With all that being said, the CERV II’s party piece wasn’t the engine that sat in the middle, but the automatic transmission and the AWD system. Basically, two Powerglide torque converters were placed up front and at the back, both with its own clutchless 2-speed manual transmission, connected by a driveshaft. With this arrangement in place, the engineers tried numerous torque split ratios and gears, Duntov aiming for about 35% of the power to be sent to the front wheels with the rest directed to the back wheels, thus creating a four-wheel-drive machine. The car sold for $1,100,000 at the 2013 RM/Sotheby’s auction in New York City.
The Chevrolet XP-880 Astro II is the second mid-engined Chevrolet project bearing the Astro name. The first, known as the Astro I Corvair Corsa, was unveiled at the 1967 New York Auto Show and was also designed by Larry Shinoda. It featured a pointy nose, a trait that trickled down into production on later C3s, an extremely slippery body and some clever technical ideas under the skin. The whole rear section including the side windows lifted up to allow access inside, where you’d go on to find not a steering wheel, but airplane-like handgrips.
The Astro II, which showed up at the New York Auto Show a year later, was less extreme in its appearance as it was closer to what a production-ready mid-engined 'Vette would actually end up looking like.
If you’re a keen fan of unusual American prototypes, you’ll find some similarities between the Astro II and the AMC AMX/3 which was developed with help from Giotto Bizzarrini, the man behind the 250 GTO.
But the Astro II, also known as the XP-880, was the car that came first. It had a luscious body that retained the sharp nose lines of the Astro I but doors were fitted for access. The extended rear overhangs are a hint that under the rear hatch there isn’t only the engine, but the radiator as well. It was powered by a big block water-cooled V-8 which was said to be good enough for 390 horsepower. The gearbox, a 2-speed torque converter lent from a Pontiac Tempest, was bolted to what’s usually the front of the crankshaft.
The finished product was Arkus-Duntov’s vision of what the next Corvette should look like at a time when Ford was rolling its GT40 Mk.III road car amidst a flurry of victories in sportscar racing. While the Astro II was 200 pounds lighter than a standard 7.0-liter Corvette C3, the suits at the top of GM thought that the public wasn’t ready for such a dramatic change to happen to their beloved Corvette.
While there was no green light on a production version of the XP-880, Arkus-Duntov and his men went full steam ahead in the development of a mid-engined Chevrolet sports car.
The XP-882 was developed throughout 1969 and finally unveiled at the 1970 New York Auto Show.
It featured many typical Corvette design cues including the grille up front and the taillights.
Apparently, two cars were built before John Z. DeLorean took over the reins as General Manager, spelling the end of this design study. It had a 6.5-liter V-8 mounted transversely that sent the power to the front wheels via an Oldsmobile Toronado Turbo-Hydramatic transmission. Both cars were heading for the crusher after DeLorean’s appointment but one did survive and morphed into the XP-895.
The XP-882 appeared on the cover of Road & Track at the time, the magazine says in big black letters that "This is the new Corvette". Well, it wasn’t, but at least is spawned the XP-895.
The decision to revive the mid-engine project came as a result of Ford’s push to sell the De Tomaso Pantera, that was powered by a Ford Cleveland V-8 engine, through its network of dealerships in the U.S. at the time. Chevrolet felt it again needed to have an answer ready to Ford and this was the XP-895.
The car received a slightly restyled body compared to the original XP-882. Bill Mitchell was again behind the design that was interesting due to its narrow nose with incorporated NACA ducts and large fender flares.
In fact, the restyled car, originally built in 1970 as part of the XP-882 project, had a steel chassis with a steel body that weighed about 3,500 pounds.
It was decided that that was way too much for a sports car so Reynolds Aluminum was commissioned to build an exact replica but with a body and chassis made out of aluminum. The finished product, nicknamed the ’Reynolds Aluminum Car’, weighed just 3,050 pounds.
According to SuperChevy.com, the XP-895 was in development roughly at the same time as the 4 and 2-rotor prototypes. All of these had the engine in the middle but they were quite different. The XP-895, as I said, was based on the XP-882 but it "was engineered to take a big-block 7.4-liter V-8 and a four-speed transmission was designed into the unique Toronado-based transfer case." What is more, "to accommodate the rear weight bias, wider tires were fitted onto the car."
Sadly, due to the high production costs involved in mass-producing a car with both the chassis and body made out of aluminum, the XP-895 was put in storage, not in production.
1973 XP-897GT Two-Rotor Corvette
GM had acquired the license to develop the Wankel technology from Mazda. Ed Cole, who was on the edge of retirement from his seat as president of GM, envisioned a future where "just three front-drive layouts, powered by two-, three-, or four-rotor Wankel engines" made out the whole of GM’s line. The OPEC fuel crisis and the postponed the introduction of this surprising plan and all Wankel experiments were shut in 1977. However, before all rotary-related within GM hit the gutter, the no-cylinder frenzy hit the Corvette as well.
The XP-897GT sat on a shortened Porsche 914 chassis and had a body designed by Pininfarina with quad recessed rectangular headlights up front and a nose similar to that of the XP-895.
The two-rotor transversely-mounted engine developed 180 horsepower - although, if developed, 250 horsepower was a plausible output - and was linked to a 3-speed automatic gearbox. The interior felt spacious with the center console angled towards the driver.
Although it featured the 914’s underpinnings, the 2-rotor Corvette prototype was 500 pounds heavier. Arkus-Duntov criticized the car’s weight and pointed out to his earlier efforts with the Grand Sport racing cars that only weighed 1,850 pounds. This Wankel car, he argued, was never going to appeal to the Corvette clientele and was a waste of time.
Indeed, the project was shelved and, in hindsight, it might’ve been better for GM to badge the 2-rotor concept as a Pontiac rather than a Corvette. After he left the company, John Z. DeLorean tried to purchase the XP-897GT to start developing his own sports car but it was to no avail.
1973 Four-Rotor Corvette
Along with the XP-897GT and the XP-895, the 4-rotor Corvette was the third mid-engined prototype that was in development in the R&D department between 1972 and 1973.
Similar to the XP-895, the 4-rotor concept was also intimately associated with the XP-882 which could be seen with the naked eye as the 4-rotor and the XP-882 were remarkably similar.
According to SuperChevy.com, Arkus-Duntov was never a fan of turning the Corvette into a Wankel-powered car. He was "familiar with the Wankel engine since 1955 and he knew that the basic design was inefficient because of the surface-to-volume ratio in the combustion chamber." But Cole wouldn’t flinch - if a mid-engine Corvette were to happen, it would have a rotary engine in it.
So, to eek out performance, the decision was made to have two 2-rotor Vega engines put together. The two units were positioned on either side of a "shaft that ran back to the bevels at the transmission output. Each engine was 90-degrees out of phase to smooth out the performance. A toothed and grooved cog belt ran the ignition, alternator, and fuel pump, while a V-belt controlled the air conditioning, power steering, and water pump." Total capacity was 9.6-liters with power conservatively rated at 350 horsepower.
The sleek teardrop design came as a result of Bill Mitchell’s desire to take the Corvette into a different direction stylistically. The work was carried out by Hank Haga and Jerry Palmer. The former would recount that "the design problem was to put together a piece of equipment that didn’t have a tail 40 feet long." To make things work, they "did several overlays and got a fair balance between the nose and tail. We kept shortening it and that’s how it evolved.”
The 2-rotor XP-897GT and the 4-rotor prototypes were presented at the 1974 Paris Motor Show, as per Duntov’s wish, but, by then, Cole’s rotary dreams were fading and everything was canceled soon after.
However, in 1975, Mitchell sent the 4-rotor car to the R&D department where it received the same drivetrain as the 'Reynolds Aluminum Car' XP-895 mated to a 6.5-liter V-8.
Along with the new engine and drivetrain came a fresh name: Aerovette. David R. McLellan, who replaced Arkus Duntov in 1974 as Chief Engineer of the Corvette, said that "showing the Aerovette was a sign of what wouldn’t be produced." Notwithstanding, some sources claim that before Cole retired in 1974, he did offer his blessing for a mid-engine Corvette that should’ve debuted as the C4 in 1980.
But McLellan had different ideas and reckoned that keeping the engine up front in the Corvette is the pragmatic way to go and the C3’s life was extended well into 1982 before another front-engined Corvette, the real C4, roamed into production.
1986 Corvette Indy
By 1986, the Corvette C4 was considered the best Corvette to date but the men behind it were already worrying about what would become of the C5. As was the case previously, the idea of moving the engine behind the seats loomed and so a slippery concept, named Indy, was born in 1986. It wasn’t a running and driving car like the Aerovette, for instance, but it would’ve incorporated a ton of interesting technical solutions.
In theory, the 4.3-liter twin-turbocharged engine sent power to all four wheels and active suspension, traction control, drive-by-wire steering, and four-wheel steering were all envisioned by Chuck Jordan, GM’s Vice-President of design. The body was built by Cecomp in Italy. Because the roofline was so low, the finished product had to be unveiled in the form of a targa so that Jordan could actually sit in it.
Nonetheless, the design impressed GM's brass and it was decided that developing running prototypes was worthwhile.
Around that time, GM had bought Lotus so the folks in Hethel put the Indy concept in the wind tunnel to see if it was as good as it looked. What they found out was terrifying: the front end generated so much lift that it actually was enough for air to get underneath the belly of the car and make it to somersault in the air at high speed.
Finally, “after many hours in the wind tunnel, we achieved a reasonable aero performance for a car that could potentially reach 200 mph,” said Peter Stevens, the Chief Design Engineer at Lotus. That was achieved by shortening the front overhang and altering the shape of the canopy. The chassis of the running prototypes were made out of carbon fiber and kevlar which was insane back in the late ’80s.
They also had both all-wheel-steering and all-wheel-drive as well as traction control, ABS, and hydraulically-operated active suspension. Look up the way the active suspension on the championship-winning Williams-Renault FW14B works to get an idea of this system. The suspension tests were the core focus of the GM R&D team which is why it’s unclear how fast the 600 horsepower Indy prototypes could go.
1990 CERV III
The CERV III was developed at the same time as the operational Indy prototypes. It featured the same twin-turbocharged LT5 engine capable of 650 horsepower and 655 pound-feet of torque with an 8.5:1 compression ratio. The design was handled by Jerry Palmer while Dick Balsley watched over the engineering side of things.
The end result was a car that was genuinely close to a production model. The nose sat higher than on the Indy, the side windows could actually be rolled down into the doors and weren’t just part of a canopy, and fuel tanks were mounted in below the doors.
The CERV III was the first AWD sports car with automatic transmission but this arrangement was far from basic.
"A torque converter was mounted to the end of the LT5’s crank, then, using a multilink chain, connected to two three-speed Turbo-Hydromantic 425 transmissions, modified with beefier 475 Turbo-Hydromantic parts. A differential with bevel gears split to the front and rear, connecting a carbon-fiber driveshaft to the front and rear Positraction differentials, according to SuperChevy.com. A computer mated to the differential judged what percentage of power should go to each of the two axles according to the level of grip of each tire.
Although the Lotus-engineered chassis weighed only 38 pounds, the whole car tipped the scales at 3,400 pounds. Still, it could sprint to 62 mph in little over 4 seconds and had a theoretical top speed of over 220 mph. All this muscle flexing would’ve translated into a $400,000 production model - and that was almost three decades ago.
Today, we look forward to a mid-engine Corvette that should cost less than half that amount. While it’s still double the price of a current ’Vette, it will incorporate more tech than the CERV III of 1990 and will be easier to build. All hail to the decades of progress that got us closer than ever to Arkus-Duntov’s dream that he never saw materialize: the mid-engine Corvette, one that might carry the name of the ’Father of the Corvette’.
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