If you wondered why Honda raced inline-4s in World Superbike and V-4s in MotoGP, wonder no more. A high-technology V-4 streetbike based on the championship-winning RC213V MotoGP racer was revealed at the EICMA show in Milan, Italy. This new machine, known as RC213V-S, may also be the basis of a future World Superbike entry. 2 examples were shown: a static bike painted with a Japanese flag to mark EICMA’s 100th anniversary and a running version in full carbon fiber ridden on stage by MotoGP World Champion Marc Marquez. Honda’s work with V-4s dates back to the daring but unsuccessful NR500 oval-piston GP project of 1977-81. Prior to that, all Honda GP engines had been inline 4-strokes, and championship-winning 4s had carried the Honda name to world prominence. Yet engineers were dissatisfied with the inline-4 because it consists of 2 180-degree twins set end-to-end. Each such twin wobbles vigorously about its center, applying a bending moment that flexes and may in time crack the crankcase and cause cylinder base-gasket leakage. To better contain this, in 1961, Honda’s racing engineers mastered the difficult task of casting the 250 racer’s upper crankcase half and the complex finned cylinder block in a single self-bracing unit. Such unit-case/cylinder construction was later applied to Honda’s CBR production inline-4s for the same good reasons.
The NR500 was built as a V-4, its crankcase and 2 cylinder blocks forming a compact, box-like structure that maximally centralized engine mass. If a 90-degree cylinder angle were chosen, the right and left cylinder pairs of such an engine could be self-balancing in the same way as Ducati’s 90-degree V-twins. NR500 failed to win a single GP point but did conceptually father the long line of Interceptor/VFR V-4s, which culminated in the World Superbike-winning RC30 and RC45. It is thought that 5 of the RC45’s highly sophisticated cylinders were the starting-point of Honda’s first MotoGP engine, the V-5 RC211V. Although for some time Honda’s V-5 and later V-4 MotoGP engine architecture was compared unfavorably with the inherently more mass-forward inline concept favored by Yamaha (whose M1 has always been an inline-4), Honda has made the V-4 dominant in MotoGP in 2011-14. Hard to argue with success! Just a year ago, Honda revealed its MotoGP production racer, the RCV1000R. With its fabulous fit and finish, that machine was hailed at the time as a likely basis for a pricey, exclusive “racer replica” to be sold to the same up-market buyers who in 2006 inhaled the 1500 Desmosedicis offered for public sale at $ 72,000 a copy. This is a natural response to the movement of disposable income up toward the tip of the economic pyramid. Because 1500 times $ 72,000 equals $ 108 million, this is not a market anyone can afford to ignore. Kawasaki’s recently announced 300-horsepower supercharged H2R is another example of such “up marketing.” It also makes sense for Honda to use the same basic R&D to cover MotoGP (with pneumatic cylinder heads), World Superbike (with metal valve springs), and a super-exclusive sports/collector market, rather than developing and producing separate designs for each. Does this foretell a general Honda abandonment of the inline-4 engine? We wait and see.