The 4-stroke NR500 was developed for Honda’s return to World GP racing in 1979. Honda decided to challenge for the title with a 4-stroke machine, in the 500cc class then dominated by 2-stroke machines. It was no easy task, with rival 2-stroke engines outputting 110PS at around 10,000rpm. For the 4-stroke NR500 to even match this output, it would simply have to rev to 20,000rpm, twice that of a 2-stroke. Honda’s aim was to output 130PS/20,000rpm, but such an engine did not exist at the time. After trial-and-error, Honda produced a radically new 4-stroke V-4 engine, with oval pistons, and 8-valves per cylinder. With its monocoque frame and use of new materials, the NR500 was packed with Honda’s advanced technologies and ideas. During development, numerous engines were sacrificed, being simply unable to tolerate such high revs. Honda kept on challenging, and in August 1979, debuted with an output of 108PS/18,000rpm. Although not quite as powerful as its initial goals, the NR500 would be further evolved over the following three years. In 1980, the NR500 returned to GP racing for three races, finishing twice, in 15th and 12th. Although in 1981 the NR500 finished only once in GP racing, the engine was steadily improved with every race, and in the end, generated 135PS/19,500rpm. The NR500 was at a disadvantage in World GP, as races at the time were push-started, favoring the lighter and easily started 2-stroke machines. The NR500 did not win any titles in World GP racing, but during the three-year challenge Honda had accumulated technologies that would be invaluable later on.