Honda’s concept of an oval-piston engine (or more correctly, a bore/piston with straight sides and semicircular ends) began with the development of the 1979 NR500 GP machine. Honda had been out of Grand Prix racing for 12 years, and when they returned they wanted to showcase four-stroke technology.
Of course at the time 500 Grand Prix was dominated by two-strokes, and that trend continued despite Honda’s best efforts with that original NR500.
“When I look back at it, I’m not sure if we were experimenting with cutting-edge technologies or obsessed with foolish ideas,” recalled Toshimitsu Yoshimura, an engineer involved in the development of the first NR500’s oval piston engine.
“At least we were doing something that was beyond the realm of conventional thinking. I’m not just talking about us, who were designing the engine, but also those who were creating the body.
“The emphasis was to create a difference-not just any difference but the difference that would work to our definite advantage. That’s why we decided that Honda should go with four-stroke engines. We wanted to achieve our target through innovative technology, and in so doing have the edge over our competition.”