HONDA The Power of Dreams

Honda’s F1 engines had won the constructors’ title for five consecutive years since 1986, but the competition was catching up. In 1991, the third year of the 3.5-liter naturally-aspirated (NA) engine era, Honda decided to introduce a V12 engine. The concept behind the research and development a V12 that was a light as a V10, without sacrificing power.

Another motivating factor for Honda to develop the RA121E was the fact that the V12 was the engine type most favored by Honda’s founder, Soichiro Honda, who passed away in August of that year.

The RA121E took two years of research and development starting in 1989. It was a 3497 cc DOHC 4-valve V12 engine with a bank angle of 60-degrees, bore x stroke of 86.5mm x 49.6mm, maximum engine speed of 13,000 rpm, maximum output of over 650 hp, and an announced weight of 150 kg.

Despite being a newly developed engine, McLaren was fortunate enough to win the first four rounds of the season, but was initially plagued with problems right up to the season-opener. The lack of rigidity of the coupling with the chassis caused vibrations, and Ayrton Senna in particular complained. In addition, they encountered piston-to-head contact issues, even though there were no problems with the design. A lot of trial and error was needed to solve this issue. Even so, RA121E rarely caused retirements in actual racing, and Ayrton Senna built up a large lead in the early stage of the season.

The total command of the Honda engine was threatened in 1991, due to rivals’ technological advances in fuel development and electronic car control. In response, Honda introduced the RA121E with expanded bore mid-season, in Round 8, the British GP. In addition, Honda established a development team separate to existing race engine development and operation team, to explore future developments. This team was instrumental in the variable intake pipe length system introduced in Round 11, Belgium. The system changed the length of the air funnel according to the throttle position to obtain the ideal engine torque for relative to engine speed, improving the torque characteristics of the RA121E, which tended to sacrifice low-speed torque due to its multi-cylinder, high-revving design and increased bore.

1991 also saw an escalation in the battle for fuel development. The effect of so-called special fuels developed jointly by engine manufacturers and fuel suppliers had a tremendous effect, and Honda was able to stay competitive with the help of Shell, McLaren’s fuel and oil supplier at the time, achieving a 100-horsepower increase in power during qualifying. Considering that a 20-horsepower increase in power output was satisfactory after a year of engine development, the effect of fuel development was enormous.

During the 16-race 1991 season, the RA121E gave Honda eight wins, or a 50-percent win average, and the contructors’ and drivers’ titles for the sixth and fifth time in a row, respectively.