That the Japanese manufacturers had displayed such a meteoric ascent since adopting Group 7 regulations less than two years earlier was astonishing enough. That the country had only hosted its first international racing event six years earlier, one in which there was virtually no domestic presence, made the speed and technology shown by the Japanese cars by late 1969 even more impressive. They were now building cars almost the equal of the front-running Can-Am machinery.

But as quickly as it had arrived, so this technological showcase was stubbed out again just as fast. For 1970, the Japan Grand Prix would be contested by single seater open wheeler racing cars as part of a long-term program to bring Formula 1 to Japan. This goal was finally achieved in 1976. Without its most prominent national event, Nissan immediately ceased its Group 7 development and withdrew from sports car racing. Toyota, despite its major rival having dropped out, continued development of a new car for 1970, the 578A. However, the intention was not to contest Japan Group 7. Instead, Toyota planned to enter the Can-Am series as part of a larger long-term plan to integrate itself into the American car industry.

Barely a decade earlier, Toyota had entered the hugely lucrative US market with its tiny Toyopet Crown. In its first year, 1958, just 290 cars were sold, barely registering a blip in the overall market. The company pushed forward its plans, but even by the late 1960s, was still very much a minor player. It was already using motorsport as part of its marketing program, and in 1968, had contracted Carroll Shelby to run Toyota 2000GT’s in C/Production sports car racing. But its Can-Am ambitions were on a much larger scale.

The 578A was a further development of the 474S, although greatly improved in every area. But its most notable advancement was that the Toyota V8 engine was now fitted with twin turbo-chargers. As it was, the Toyota V8, designed and manufactured by Yamaha, was a work of art. Using an aluminium block, four camshafts, a flat-plane crankshaft, fuel-injection, and dry-sump, it produced around 550 horsepower in normally-aspirated 5 litre form. But it couldn’t be made any larger than 5,000cc. In 1969, front-running Can-Am cars were using 7 litre aluminium big block engines, producing over 700 horsepower. Clearly, the little Toyota engine would come up well short. So an intensive development program began to turbocharge the Toyota unit, using two Garrett AiResearch turbines.

By the time Toyota began testing the new turbo car, the engine was producing 800 horsepower and 534 lbs ft of torque. This, in a car weighing little more than 650 kilograms. Toyota had perhaps the most powerful circuit racing engine in the world at the time. But on the track, the turbochargers produced massive lag exiting slower corners, before suddenly spooling up to deliver an explosion of uncontrollable power. The drivers were terrified, and found the car incredibly difficult to drive. In 1970, turbocharging in circuit racing was still a black-art, even for a car manufacturer with massive resources.

It was while testing the turbocharged 578A at Suzuka in August 1970 that star-Toyota driver Minoru Kawai lost control and crashed. He succumbed to his injuries. A year earlier, another Toyota driver had been killed testing a Toyota Group 6 sports car at Suzuka. Quietly and immediately, Toyota cancelled its Group 7 program, and the 578A never raced.

Although turbocharging was common in Indycar racing by 1970, its development and understanding in circuit racing had not yet been overcome. In 1971, Porsche teamed up with Penske Racing, and developed a turbocharged 917 for the Can-Am series, which it designated the 917/10. The testing program was intensive, but proved ultimately successful. The Penske/Porsche collaboration finally trumped the dominant McLaren team, which had won the Can-Am championship every year from 1967 – 1971. The 917/10, and in particular, its turbocharged technology, was such a game changer, that McLaren withdrew from the Can-Am series at the end of the season.

History shows that Porsche slayed the mighty McLaren in the Can-Am series. But Toyota had a turbocharged Can-Am car on the track before Porsche did. Had Toyota overcome its massive turbo-lag problems, had Minoru Kawai not been killed testing the new 578A, had the Japan Grand Prix continued using Group 7 sports car regulations in 1970 and beyond and the Japanese manufacturers continued their impressive technological progress, its very likely Japan Group 7 might now be widely remembered and understood by all. Instead, it’s a brief period in history very few, other than the most dedicated of motorsport archaeologists, know anything about. But it deserves so much more.

Main photo courtesy Duncan Fox Collection.

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