A while back, we wrote about how Honda used miniaturization with the RC166 to create a 6 cylinder 250 cc Grand Prix bike in order to compete with the two strokes. But they weren't the first to attempt this approach. Moto Guzzi had given it a shot over a decade earlier.
Moto Guzzi is largely known today for their dogged commitment to the longitudinal V-Twin engine on all their bikes. That clearly wasn't always the case. The Moto Guzzi V8, also known as the Otto (for 'eight') motorcycle, was designed by Giulio Cesare Carcano, specifically for the Moto Guzzi Grand Prix racing team for the 1955-57 seasons. The Moto Guzzi Otto motorcycle and its engine represent a unique and historically significant engineering milestone.
Though it could be said it followed the two-stroke Galbusera V8 of 1938, the Moto Guzzi engine and the bike were truly without precedent. A water-cooled, 500 cc 90 degree V8 with dual overhead cams and a separate Dell'Orto carburetor for each of the eight cylinders. The engine weighed a scant 99 lb, allowing the overall bike weight to stay at 325 pounds. The tightly packaged engine produced an unprecedented 72 hp at 12,000 rpm. The motorcycle proved capable of hitting 172 mph — brutally fast for the day. It would be 20 years before the speed was reached again in Grand Prix motorcycle racing.
Interestingly, the began with a 6 speed gearbox, then dropped to a 5 speed and finally ran with a 4 speed.
The Otto was raced with 2 different fairings, one much like a modern fairing leaving the front wheel exposed and the other, the famous "dustbin" with greater coverage, the choice depending on the track.
Despite all the power and speed the Moto Guzzi could generate, tire, brake and suspension technology weren't up to the same levels, making race course field testing difficult and racing dangerous. Fergus Anderson crashed the motorcycle on its maiden run in Modena. Only Fergus Anderson, Stanley Woods, Dickie Dale, Ken Kavanagh, Keith Campbell, Giuseppe Colnago and Bill Lomas were the only people able to even ride the V8 motorcycle. Several of the riders experienced spectacular falls. Bill Lomas suffered an unfortunate head injury at the 1956 Senigallia Grand Prix. Ken Kavanagh ultimately refused to ride the motorcycle after the 1956 race at Spa-Francorchamps.
The Otto was, not surprisingly, quite complex and expensive to build and maintain. Bikes suffered broken crankshafts, overheating, and seizing, all of which added to the danger the bike posed to the racers themselves. By 1957 there were two bikes available and no one willing to race the bike without further development. Instead, Moto Guzzi shelved further development of the Otto remained undeveloped, and they and other manufacturers withdrew from racing entirely in the 1957 season. It is widely believed that with further development, the V8 could have proven a formidable Grand Prix contender.
Two authentic examples of the engine remain in the possession of Moto Guzzi, at the Moto Guzzi Museum in Mandello.