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Group C: The Rise and Fall of the Golden Age of Endurance Racing: Mazda

Submitted by on October 20, 2020

By Marcel Hundscheid / Speed-O-Graphica

In part 11 of our Group C retrospective, we take a closer look at the sports cars that were built by Mazda for Group C competition, starting with the 717C, 727C, 737C and finally the Le Mans class-winning 757.

Mazda started their GT outfit with the rotary powered RX7 in 1979 with relative success, but it would be 1983 before they entered Group C with their 717C.  The new 717C was designed by Takura Yura of Mooncraft who was also responsible for the earlier RX7.

Yura selected a 1.3 litre rotary engine that was used on the RX7 and paired it with a Bosch electronic fuel injection system to build the new 717, which ended up generating 310 hp at 9000 rpm. Ultimate top speed is the key at Le Mans on the long straights. Therefore, Yura created a very smooth bodywork featuring enclosed rear wheels. In the end the 717C measured four meters in length with a weight of just 760 kgs.

The car debuted at the Silverstone 1000 km in 1983. Driven by Pete Lovett and Youjiro Terada, it qualified 21st overall, however a loose wheel prevented it from seeing the chequered flag. At the 24 hours Le Mans a second chassis appeared, this one driven by Jeff Allam, Steve Soper and James Weaver. The two cars became the only finishers in Group C Junior, finishing 12th and 18th overall. Mazda’s 717C had become a class-winning car during its debut and proved that rotary power was a legitimate threat.

The 717C was followed by the 727C in 1984. The 727C was fitted with the same engine as used in the 717, the 310 bhp Mazda 13B rotary engine. Two cars entered the Le Mans 24 Hours in 1984, but both would run into trouble during the race. The #86 car had transmission issues and was involved in a collision with another car, while #87 suffered from suspension issues. In the end both cars finished, and claimed 4th and 6th in Group C2.

The 737C from 1985 was the final evolution of the 717C and used that same Mazda 13B rotary engine. The factory entered two 737Cs for the ’85 Le Mans 24 Hours and despite fearsome troubles, both cars completed the race finishing 3rd and 6th in Group C2.

With Mazda completing a new rotary engine capable of 450 bhp, they needed a new machine for it to push around. To that end, British designer Nigel Stroud designed a new Group C/GTP racer – the Mazda 757. The 757 was given an aluminium monocoque chassis clothed in a carbon fiber body. It debuted at the Suzuka 500 kms in April 1986, followed by two entries at Silverstone. At the 24 Hours of Le Mans, although they were the fastest cars in the GTP class, both cars retired due to gearbox problems.

Mazda refined the 757 for the 1987 season, fitting it with a three-rotor 1962 cc engine generating 450 hp. The pair of 757s that entered Le Mans were lighter and featured several technical improvements over the previous year’s model. The setup of the cars was also adjusted to accommodate changes in the circuit, including safety changes at the chicane.

Just two hours after the start, one car stopped with engine failure. The second car had a problem with the windshield wipers and a broken left rear suspension, which forced it into the pits, however, it was soon able to return to the track. Later in the race, with the top teams retired due to multiple crashes, the Mazda 757 went on to score the best finish ever for a Japanese car: seventh overall and first in the IMSA GTP/GTX class.

That wasn’t the end of Mazda’s Group C campaign, however, with some of their best efforts yet to come. Stay tuned for part 2 of our look at Mazda in Group C.

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