It is believed that Honda abandoned further development of the V10 engine because the power advantage was gradually passing to the Ferrari V12 units. In the 1990 season, it looked like this, because it was the Scuderia who were the first to exceed the liter power figure of 200 hp per liter. But in fact, the main “culprit” that pushed Honda to the transition to V12, was Soichiro Honda, back in the spring of 1989 insisted on the development of a V12 engine. The prototype of the new engine was run on the stand already in October of the year, and a little later it was demonstrated at the Tokyo Motor Show. From the receipt of the technical specification to the first working prototype took only 8 months!
In June 1990, at the height of the battle for the championship between Senna (McLaren Honda V10) and Prost (Ferrari V12), the first tests of the latest power unit were conducted at Silverstone circuit. Later the tests continued on the tracks: Monza, Hungraroring and Estoril. As you can see, the variety of tracks was maximum, from high-speed to very slow.
In addition to the new V12, cars with the current, at that time, V10 engine participated in the tests — for comparison. Theoretically, all the advantages were on the side of the V12. It was only 5 cm longer, but 3 cm lower and 1 cm narrower, and what is surprising both units weighed the same, 150 kilograms! The point is that the new engine had no balancing shafts. Michio Kawamoto, chief of Honda racing division, announced that the new engine “develops much more power than the previous one”, but these words were questioned by Gerhard Berger, who said after the first tests that the new V12 was inferior to last year’s V10.
Who was right? Berger, most likely. Nevertheless, in the debut of the season 1991 Ayrton Senna on McLaren MP4/6 with a Honda RA121E engine won the first four rounds in a row! This had never happened before. But the main competitor pilots McLaren was no longer Alain Prost from Ferrari, and pilots Williams, using the engine Renault V10. French motors have noticeably progressed, and gradually from the initial advantage of Honda was not left any a trace. It was obvious that the Williams chassis is superior to McLaren, and the Renault engine is more powerful than Honda. In Silverstone, the maximum speed of cars Williams-Reanault reached 338 km / h, against 325 km/h for McLaren.
Ironically, it was in England, after intensive test work, that Honda developed another version of the engine — “Spec 3” or RA121E/B. As journalists of the time wrote, “testing of the new engine was interrupted only at night”. But the debut ended in failure: in Silvertone, a noticeably behind in speed McLaren Senna, ran out of fuel. At the next stage, in the German Hockenheim, this situation was repeated — Senna again ran out of gas! Obviously, the new engine has become noticeably more voracious, but not too much to add to the power. Having won the first four stages, further McLaren-Honda failed to win in 5 Grand Prix in a row!
It seemed that the initiative completely seized in the team Williams-Renault, but to Honda’s credit they managed to reverse the situation — the power of the engine inevitably grew, while the fuel consumption managed to curb. Starting from Belgium, Honda, following Renault, began to use variable geometry intake with telescopic intake nozzles. This allowed, without sacrificing maximum power, to increase maximum torque at low and medium speeds. As a result of all of the above, in the final version of the engine, the maximum engine speed increased from the original 13000 rpm to 15000 rpm.
Technical specification of Honda RA121E/B engine (different data of the first version in brackets)
✅️ Displacement: 3,498 cm3 (3493 cm3)
✅️ Number of cylinders: V12, 60º.
✅️ Cylinder diameter / stroke (mm): 86.5 / 49.6 (83 / 53.8).
✅️ Power: 764 hp at 13700 rpm (????)
✅️ Dimensions, length / width / height (mm): 670 / 520 / 530
✅️ Engine weight: 150 kg.
McLaren-Honda managed to win the championship, but it was obvious that the Williams-Renault combination looked preferable. The McLaren-Honda team’s success was due to two important factors. One, they had Ayrton Senna at their disposal. Second — Williams had problems with the reliability of the semi-automatic gearbox at the beginning of the championship.
For the early 90’s this is very high power!