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Oh, oh?.. Even three dozen years ago, the advent of aircraft with gas turbine engines promised "something from nothing" not only in aviation but also in other industries. Renault first tried to use turbocharging on asphalt in endurance racing and Formula 1 racing cars, and behind it Porsche and truck manufacturers who tried to compensate for the unimportant acceleration of cars with traditional diesel engines. The exhaust gases brought the pump into operation, which compressed the incoming fresh air charge. There you have it, mother nature, and something out of nothing!.. Everyone thought so until they calculated the “victims”. But they are numerous: there is a delay in the “response” to gas, fuel consumption has increased, the size and weight of the machines have increased after installing turbo equipment, the cooling system has become more complicated - you had to “fight” with the temperature that increased when the turbocharger was working. Hopes burst - and the designers returned to traditional motors.
All four Japanese motorcycle manufacturing companies that took on turbo engines, and with them Moto Morini, admitted that the losses outweighed the acquisitions … A quarter century has passed since you could still buy a motorcycle with a turbo engine. The unsuccessful Honda project, which created a 250 cc V-engine with oval pistons and turbocharging for the GP-500 cm3 class, once again proved that this thing is not suitable for motorcycles.
Mechanical boost is a different matter. This was recognized by car manufacturers: at first Lancia, followed by Cadillac, Mercedes-Benz, Jaguar, and now many others, including BMW (with its Mini Cooper S). Using a compressor that is driven mechanically does not cause problems with a reaction to gas or excessive heat, like a turbo engine. In this case, a significant increase in power can be achieved. Until now, the overweight and large sizes of the supercharger, even compared to the turbine, and the need to compensate for the part of the power that was lost on the drive, made the boost suitable only for drag racing. But times are changing, a new generation of compressors has appeared, as well as technologies to synchronize their work with the electronic engine management system … It’s strange, why in the world of motorcycles so far no one has paid attention to these finds?
The leading designer and designer of Great Britain, Russell Savory, is only concerned with arguing with nature. On orders from Yamaha and Honda, he created sportbikes (his CBR900RR Fireblade in TT racing on the Isle of Man won the hundredth race for Honda in 1998), and completed a series of interesting projects based on Yamaha engines. Among them, a two-liter 8-cylinder V-shaped engine with a fuel injection system, consisting of a pair of FZR1000 EXUP engines with a common crankcase and a power of more than 320 hp They are about to go on sale on a limited batch of Caterham machines. "Made" Sawori and the 5-valve 1-cylinder engine XTZ660 with a fuel injection system, which was installed on the first MuZ Skorpion Supermono race car. "His own pen" belongs to the 4-valve RS660, which debuted two years ago. And the 180-horsepower Honda Fireblade ultra-bike, built for discerning customers like the McLaren-Mercedes F1 engine designer Graham Langham. And … in short, the picture is clear: Russell Sawory has an inquiring mind.
When a Yamaha representative came to him in 1993 with the idea of developing a 1-cylinder supercharged engine, Russell again became interested. He was ordered a motorcycle that could withstand the power advantages of the 900 cc Cagiva Elefant with a V-engine (they became the main rivals in the Paris-Dakar races), but would retain a small weight and good maneuverability. Russell fell into excitement, rubbed his hands and set to work.
Two years later, appeared RS Tramontana ("Hot Wind") based on the Yamaha XTZ660. He became a "living" proof that the boost works. If you think that you got an old-fashioned concept that is more suitable for racing in the pre-war years of the last century (when the “four” Gilera Rondine Compressore or twin BMW Kompressor competed with a breathless AJS V4 or stillborn Velocette Roarer with supercharging), I advise you not to rush to conclusions.
The numbers say: the base Yamaha XTZ660 gave out 37 hp. on the RS dynamometer. And the same engine, but with supercharging developed 72 hp. at the same stand! Absolutely no tuning. Camshaft, valves - basic. The compression ratio was reduced to 9: 1 (using an Omega forged piston mounted on a Carrillo connecting rod). Unless they strengthened the crankshaft, this is so that it would not be destroyed by colossal power. What is the trick? Everything is simple - set the boost.
