The FIA introduced the Group C category in 1982 as a replacement for both Group 5 Special Production Cars and Group 6 Two Seater Racing Cars. Cars that raced in the Group C category were eligible for the World Championship, which included the 24 Hours of LeMans.
The North American IMSA Grand Touring Prototype series (GTP) used broadly similar rules to Group C, with races primarily occurring in the United States, and sometimes in Canada. The main difference between the two categories was that GTP had no emphasis on fuel consumption while Group C cars limited the amount of fuel available for a race. The GTP cars had a displacement limit based on the overall minimum weight.
The Group C category was dominated by the turbocharged boxer engine powered 956, which had already been tested and proven in the 1981 Group 6 category. The GTP attracted a wider array of manufacturers with the first GTP champion being Brian Redman driving a Lola T600 with a Chevrolet engine. March had also fielded prototypes, with Al Holbert winning the 1983 championship with a Chevrolet powered car.
March entered a car based on the M1C project they had worked on for BMW. By 1983, designer Adrian Newey was working for March and was tasked with designing the 83G, an evolution of the 82G that in turn was inspired by the M1C.
The 82G had an aluminum honeycomb monocoque chassis, designed by Adrian Newey and Robin Herd, with double-wishbone suspension. Max Sardou designed the bodywork which incorporated ground effects to allow air to flow to the Venturis located under the body. Its unusual shape with a large hole located between the front fenders earned it the nickname 'lobster claw.' The body would be mildly updated through the years, through the final evolution - the 85G, while retaining the same unique shape. Mounted mid-ship was a Chevrolet V8 engine, however, the engine bay had been designed to accommodate a variety of engines making the 82G (and later models) useable in other racing series.
The 83G was similar to the 82G with four cars being built to GTP specification and one for Group C competition. Al Holbert acquired three of the GTP cars and fitted Chevy V8 engines in two of the machines. The other received a Turbocharged Porsche flat-six engine which proved to be successful, winning every race it was entered in the season and earning Holbert the IMSA Championship.
The 1984 March car was the 84G, again having only minor revisions over the prior year's model, the 83G. Seven examples were built with engines being sourced from Porsche, Chevy, Buick (a turbocharged V6), and a Mazda (rotary). Ventilated disc brakes were located at all four corners and steering was by a rack-and-pinion unit. The body was made of kevlar and carbon fiber and the overall weight was just under 2,000 pounds. The Porsche Type 935/76 B6 all-aluminum DOHC engine displaced 2,650cc and used Bosch fuel injection and twin KKK turbocharger. The Mazda 13B R2 engine displaced 1,308cc and used twin Hitachi turbochargers to produce approximately 500 horsepower. The Chevrolet all-aluminum, 5736cc, overhead valve engine was naturally aspirated and produced approximately 620 horsepower, about the same as the Porsche engine.
Randy Lanier and Bill Whittington driving the Chevy-powered 84G was very successful and was crowned IMSA Champions.
The flat-six cylinder Porsche engine used in the March inspired Porsche to build their own GTP car for the following season. When the Porsche 956 based 962 prototype racer was introduced mid-way through the season, it quickly became the car to beat, with Al Holbert and Derek Bell earning five victories during the remainder of the season.
The final evolution was the 85G introduced for the 1985 season with 11 examples being built. BMW and Nissan ordered three to Group C specifications. A March with a twin-turbocharged Nissan V6 engine scored a World Championship victory at Fuji. Another 85G won the GTP class at the 1986 Le Mans race.
For the next season, an all-new car was designed and dubbed the 86G. Nissan raced the 86G in Group C while BMW raced it in the IMSA GTP. An additional privateer example was built. by Daniel Vaughan | Apr 2020
Related Reading : March G History
The early 1980s was an exciting time for motor-sports, especially due to the introduction of the new FISA sanctioned Group C and the IMSA GTP regulations. Group C cars were eligible to contest for the World Championship with such prestigious venues as the 24 Hours of Le Mans. The GTP regulations, though similar to the Group C category, were endurance races in the United States. The purpose of having.... Continue Reading >>
In 1981 a completely new generation of sports racers saw the light of the day. The reason for this were the Group C/GTP regulations that came into effect on January 1st of that year.....[continue reading]
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