1990 Mazda RX-7 GTO

Mazda entered the North American IMSA GT Championship in 1978 with the RX-3. The information gained during the reason season helped in the development of the RX-7 the following year.

GTU
For 1979, Mazda raced their new RX-7 GTU (GTU represented 'Grand Touring Under 2.5L') The engine was built by a company called Racing Beat. It was a naturally aspirated 2-rotor unit that offered 250 horsepower at 9,500 RPM. Two of the cars qualified for the 24 Hours of Daytona and would finish 5th and 6th overall and won their class. This would be the start of many podium finishes for the RX-7.

Two Mazda RX-7s were entered for the 1980 season. They would finish on the podium in every race during the season, earning them the constructor's championship before the season was over. They had secured the championship with three races remaining.

After the 1980 season, Mazda withdrew its factory support and did not field a factory team. Many privateers continued to race their own RX-7s, and the factory drivers found homes with these private teams. Nevertheless, the RX-7 continued to dominate the series and won the GTU driver's championship from 1980 to 1987.

In 1990, Mazda won the GTU Championship with a factory-backed MX-6.

For ten years in a row, staring in 1982, the Mazda RX-7 won its class in the IMSA 24 Hours of Daytona race. It would win more IMSA races in its class than any other model of the automobile, with its one-hundredth victory on September 2nd, 1990.

GTO
The IMSA GTO category were Grand Touring-type cars with engines of 2.5-liter displacement or more, with the letter 'O' representing 'over 2.5L.' By the time Mazda entered the IMSA GTO category, it was more than just about displacement size. These were now purpose-built race cars that shared little with their production counterparts.

The Mazda RX-7 GTO was powered by the '13J' rotor engine with 600 horsepower and 529 NM of torque and mated to a Hewland five-speed gearbox. Designer Lee Dykstra was hired to design the car. The engine was mounted into a steel spaceframe chassis and the suspension was comprised of double wishbones at all four corners, with dampers and springs in the front actuated by push-rods. Ventilated AP disc brakes provided the stopping power. The exterior was clothed in aluminum and carbon-fiber panels, and although there was some resemblance to the production car, the GTO was much lower and wider.

The team was run by Dick St. Yves with Pete Halsmer and Jim Downing tasked with driving duties. At the 1990 Daytona 24 Hours, the RX-7 GTO earned pole position but was forced to retire during the race due to engine problems. The second car finished second in class. Halsmer scored the new Mazda RX-7 GTO's first victory during the fifth round of the season at Topeka. It was followed by another victory at Mid-Ohio. At San Antonio, the GTO class victory was the 100th class win for the RX-7 in IMSA competition.

The lessons learned during the 1990 season helped the team (drivers Price Cobb and Halsmer) dominate the IMSA GTO class in 1991. Halsmer won three victories and Cobba won twice, earning Mazda the IMSA GTO championship. After the season, the IMSA GTO effort came to an end and the two cars were sent back to Japan. Mazda would focus on the IMSA GTP campaign for 1992.

by Daniel Vaughan | May 2019