Sunday, July 21, 2019

The Push Backwards: The Chevrolet Corvette's Long Path to Mid-Engine Production (Part 2)

Photo Credit: Chevrolet



Though the commitment to a Chevrolet Corvette with an engine positioned ahead of the passenger compartment remained the production standard for another generation, a host of concept cars would continue to sell notion of a different powerplant layout. Intended as a research vehicle, the Astro I featured a fiberglass body that did not use conventional doors. An electric-powered roof would open in concert with elevating seats provided a unique entry and exit experience for passengers for a vehicle measuring only 35.5 inches in height. Finished in Crimson-Flame Acrylic Pearl paint, the Astro I design study also consisted of an air-cooled engine, fully automatic air conditioning, twin grip steering wheel and active aerodynamics to facilitate emergency stops. Another concept vehicle displayed a more reality-focused proposal. The XP-880 concept car came to fruition in 1968 under the engineering expertise of Frank Winchell and Larry Nies. Using existing production components, the XP-880 (later be known as the Astro II) was exhibited as a practical possibility and made its first public appearance at the 1968 New York Auto Show. An XP-882 concept followed shortly after the Astro II featuring a transversely mounted V-8 powerplant.


Image from Chevrolet Astro I brochure.



In the 1970s, the experimentation of a mid-engined Corvette also involved the thought into a bold, new powerplant option. General Motors was one of several auto companies seriously evaluating rotary engine technology. Power density and fewer moving parts made rotary powerplants an attractive consideration for future sports cars that than-GM president Ed Cole would influence the corporate design staff and Chevrolet Engineering into the creation of two Corvette concepts.

The first was a Corvette 2-rotor that included a transversely-mounted 4.4-liter power unit connected to a three-speed automatic transmission. Incorporating fixed quad headlights into its sleek design, the Corvette 2-Rotor was also heavily outfitted with production-ready safety and convenience features such as tilting steering wheel, adjustable pedals, energy-absorbing bumpers and an 8.1 cubic foot luggage compartment.


Image taken from Corvette 2-Rotor brochure



The second rotary-powered, mid-engined Corvette debuting in 1973 would draw the most eyes. The Corvette 4-Rotor concept projected an even greater level of extremes for the sports car with the 6.4-liter displacement rotary engine generating an estimated between 350 and 400 horsepower. Bi-folding doors, fully-independent suspension as well as an on-board computer with a digital display was also found on the Aerovette. Rotary engine power would eventually be dismissed by General Motors as fuel economy and reliability issues caused it to lose favour as a viable production possibility. The second concept would found new life when Chevrolet replaced the rotary engine with a V-8 powerplant. A deeply raked 72-degree V windshield and a super aerodynamic fiberglass shape conforming to a 0.325 drag coefficient design resulted in the popular Aerovette in 1977.


Images taken from Corvette 4-Rotor brochure



Zora Arkus-Duntov retired from General Motors in 1975 leaving his plans for a rear mid-engined production Corvette unfulfilled under his guidance. Duntov’s immediate successor Dave McLellan was less enthusiastic about a mid-engine design as work would start on the C4 design. Designer and loyalist to Duntov’s vision Jerry Palmer reportedly commissioned the Chevrolet designers to explore a mid-engined Corvette using a turbocharged V-6 engine but were ultimately dismissed by McLellan who favored the more conventional, familiar front-engine layout.

While the Chevrolet Corvette lost its main champion for a mid-engined layout, the vision remained in General Motors through the 1980s. As the fourth-generation Corvette would go on sale, the essence of the American sports car also appeared on the race track in the form of a mid-engined prototype race car. The Corvette GTP was manufactured on a Lola chassis but featured bodywork resembling the latest C4 design. Debuting at the 12 Hours of Sebring in 1985, the Corvette GTP was powered by either a turbocharged 4.3-liter V-6 or a 5.7-liter V-8 engine. Lee Racing first campaigned the car but was joined later in the 1985 season by Hendrick Motorsports who fielded a GM Goodwrench-sponsored machine. Over the course of five seasons, success on the race track for the Corvette GTP was limited to only two wins scored by the Hendrick Motorsports team in 1986.


Corvette GTP on cover of information brochure 



Despite a sadly lackluster outing in prototype sports car competition, the Corvette GTP would serve as inspiration for a motorsport-themed concept car. Premiering to the public in 1986, the Corvette Indy was an all-out technological and design research study into what the future of the high-performance car would look like. The Corvette Indy wore rounded, bubble-like exterior styling was reminiscent to the prototype race car while packaging a host of high-tech features.


Photo Credit: Chevrolet


The two-passenger interior incorporated a wraparound dash panel that extends controls onto the driver’s door while three CRT displays were positioned inside (one mounted far forward as a rearview monitor). Powered by a turbocharged, 2.65-liter overhead cam V-8 engine based closely on the powerplant used by IndyCar teams at the time (hence the name of the concept car), the Corvette Indy also employed computer traction control, drive-by-wire controls and four-wheel drive. Four-wheel drive was previously envisioned on mid-engined Corvette-related design studies such as the CERV II. Four-wheel steering and a Lotus-developed active suspension system were also installed on the Corvette Indy (the latter technology was briefly tried on one of the Corvette GTP race cars in 1987.


Image of interior pod for Corvette Indy located within product brochure



In 1990, the CERV III concept car debuted featured a similar design to the Corvette Indy but utilized extensive carbon fiber construction and added production design cues including pop-up headlights as well as a C4-style roof pillar. The CERV III also included the propulsion of a twin-turbocharged 5.7-liter V-8 LT5 engine that produces 650 horsepower allowing the vehicle to reach a top speed of 225 miles per hour.


Photo Credit: Chevrolet



Although the Chevrolet Corvette retained a front-engine configuration through the C5, C6 and even the C7 models, rumours of a rear mid-engined version of the sports car coming persisted. In 2012, the idea was utilized again for a race track-prepped Corvette debuting as a Daytona Prototype sports car racing class machine. Like the Corvette GTP, the Chevrolet Corvette DP was constructed on a purpose-built race chassis fashioned with bodywork resembling the production car. Over a five-year run in the Rolex Sport Car Series (later becoming the IMSA WeatherTech SportsCar Championship), the Corvette DP accumulated 30 wins and four constructors’ titles.

With a mid-engined Chevrolet Corvette finally emerging as an imminent production reality, it could be seen as both exciting and scary to think of how much the classic American sports car may change in the future. Perhaps its only evolution to envision a hybrid powertrain or even all-wheel drive for the car. Maybe even a companion crossover version of the Corvette is on the cards. Now entering eight generations, the Chevrolet Corvette continues to concede to the imagination of performance fans.

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