Honda’s RC45 on the left and RC51 on the right.
Working out the bugs.
The “plan” is the new model—a gamble that preproduction testing will discover any significant design or manufacturing problems before buyers roll out of showrooms on the new product. The “enemy” is the conditions encountered in use.
Wright Aeronautical first ran its 18-cylinder R-3350 prototype aircraft engine in late 1936, but some 3,000 engineering changes were required to push it through the standard 150-hour Type Test to qualify it for flight. It was chosen to power the B-29 bomber of World War II.
The RC45 program, despite producing only a single world championship, proved a body of technology…
At the beginning of the R-3350 program Wright had every reason to be confident, as it was having a long run of success in developing the single-row nine-cylinder R-1820 (which later powered sky-darkening numbers of B-17s). Its power increased rapidly, it cooled acceptably, and it displayed good reliability. Further, Wright had on December 1, 1935, begun development of the 14-cylinder two-row R-2600, whose progress was equally rapid and uneventful.
Having thus proven the all-important cylinder-and-head units on these two designs, and showing it could rapidly scale a single-row nine into a two-row 14, the 18-cylinder version’s success seemed assured. Yet it suffered one fundamental trouble after another—overheating, backfiring, catching fire internally, suffering unreliability from vibration, and digesting its propeller reduction gearing. These problems delayed production by at least nine months, despite the highest of program priorities. When WWII ended, the troubled wartime design was quietly terminated. In its place came an all-new design, sharing nothing with the B-29′s engine but its bore and stroke, number and arrangement of cylinders, and the designation R-3350.
While third-party testing of the wartime 3350 revealed that its claimed 2,200 takeoff horsepower was actually more like 2,050, the redesigned postwar engines went on to achieve 3,400–3,700 takeoff horsepower and set records for cruising fuel economy, permitting for the first time direct flights from NYC to London or Paris. The postwar engine, incorporating what had been learned from the wartime engine’s failures and shortcomings, achieved design maturity.
When Honda’s long-serving Superbike, the V-4 RC30 (World Superbike championships in 1988 and 1989), had been developed as far as was practicable, it was replaced in 1994 (some say years too late) by the RC45, which won its single World Superbike championship three years later, in the hands of John Kocinski. Both bikes were “homologation specials,” which means they were designed and produced for the sole purpose of homologating them as eligible for a production-based racing class. Only 3,000 RC30s were produced, and 578 RC45s.
RC45 came into being with a strange fuel-injection system controlled by a number of tiny switches—a system that had to be replaced by a much more sophisticated digital controller delivering fuel through (then) new multi-hole injectors. Its chassis began life with the RC30′s “vague” and very stiff front end, but was toward the end given the “engineered flex” treatment that would later transform Honda’s V-twin RC51 Superbike. Inheriting RC30′s marginal original oiling system (con-rod big-end bearing shells showing ominous dark streaks but never actually becoming a disaster) in its final year, the RC45′s crankshaft was switched to end-feed. The dark streaks disappeared and oil pressure could be safely reduced to 12 psi. In 2020 the new Fireblade 1,000cc inline-four’s engine (again, a homologation special for use in World Superbike) was given end-feed oiling at both crank ends. Further, the final RC45 gained about 4 hp by operating its crankcase at low pressure to enable use of low-pressure oil scraper rings.