Remembering Kenichi Yamamoto, patron saint of the rotary engine

Kenichi Yamamoto behind his desk

Every enthusiast should pause and pay respect to Kenichi Yamamoto, a true friend of sporting automobiles, who died on December 20 at the age of 95. Born in 1922 in southern Japan’s Kumamoto Prefecture, Yamamoto overcame daunting hardships to help Mazda emerge from World War II as an automotive powerhouse (literally).

Upon completion of his Imperial Navy service, Yamamoto returned to Hiroshima to mourn the loss of both his sister and his parents’ home. Shrouded from the atomic blast by a mountain range, Mazda factories were largely unscathed, so he took a job as an assembly-line worker at the company’s transmission plant. The mechanical engineering expertise he had gained at Tokyo Imperial University (now Tokyo University) was soon recognized, prompting a promotion to Mazda’s engine design department. Yamamoto was only 25 when he led the design of Mazda’s first overhead-valve engine.

In 1961, pressured by the Ministry of Transport to merge with one of Japan’s larger auto brands, Mazda president Tsuneji Matsuda desperately sought some means of distinguishing his firm from Isuzu, Nissan, and Toyota. He selected the Wankel engine, invented by German Felix Wankel, as a means to that end and assigned Yamamoto to lead 47 Mazda engineers pursuing development.

Initially hesitant because of the steep challenges involved with perfecting any new and different engine design, Yamamoto had a working prototype ready for the 1963 Tokyo motor show and the Mazda Cosmo sports car in production four years later. In 1970, the budding Mazda Motors of America organization began selling twin-rotor R100 and RX-2 sedans in a few western states.

Kenichi Yamamoto
Kenichi Yamamoto
Mazda

While Yamamoto’s team overcame rotor apex sealing issues that plagued NSU Wankels, there were other problems to contend with. The 1973 oil crisis exposed the rotary’s poor fuel efficiency, which concerned Yamamoto even before development had begun in earnest. In addition, Mazda rotary engine O-ring seals between the rotor housings and end plates failed, necessitating a southern California engine rebuild center and extended powertrain warranty coverage.

Nonetheless, a rotary with improved fuel efficiency and effective sealing was perfect for the Mazda RX-7 coupe, born in 1978. Even though the engine produced only 100 horsepower, its compact size kept this new sports car’s curb weight low, aiding every phase of performance. The RX-7 was an instant hit, with more than 140,000 sold during the model’s first two years on the market.

Yamamoto climbed from Mazda’s head of research and development to become the firm’s president in 1984. Unlike most Japanese auto company executives, his command of English was excellent and he enjoyed a sincere appreciation of Western culture. Under his guidance, Mazda’s U.S. R&D, the company’s relationship with the Ford Motor Company, and U.S. motorsports all thrived.

That same year, Mazda broke ground on its Flat Rock, Michigan, manufacturing plant, with a smiling Yamamoto enjoying the festivities. He became the company’s chairman in 1987, the year Flat Rock commenced production of Mazda’s MX-6 and Ford’s Probe coupes. In 1991, Mazda won the 24 Hours of Le Mans with its four-rotor 787B, an accomplishment unmatched by any subsequent Japanese-based racing effort.

Kenichi Yamamoto in front of a Mazda race car
Kenichi Yamamoto
Mazda

Yamamoto’s congenial relationship with journalists was legendary. Shortly after the RX-7’s launch, writer Bob Hall began urging him to pursue a second, more-affordable sports car by recycling the rear-drive GLC econocar platform. Yamamoto took the suggestion more seriously than Hall (who subsequently joined Mazda’s U.S. R&D effort) could have imagined. Instead of recycling any existing parts, Yamamoto approved a clean-sheet design with fruitful collaboration between Japanese engineers and U.S. designers and product planners.

The resulting MX-5 Miata arrived in 1989 with the best features of classic British sports cars and none of the shortcomings (reliability, weather sealing, leaking fluids). The fourth generation arrived for the 2016 model year, distinguishing the Miata as the best-selling open sports car in history, with devout admirers all over the globe.

Yamamoto handed the reigns to his successors in 1992, the year he turned 70. After his departure, rotary production ended and Mazda ceased vehicle production in the U.S. All development, production, and ownership relationships with Ford have also been severed.

Yamamoto enjoyed his 25-year retirement in good health and lived in Japan’s central Kanagawa Prefecture until his death. Fans of Mazda’s rotary-engine sports cars are forever in his debt.