Turbocharging engines is nothing new. In 1909, a native of Switzerland by the name of Herr Bchi came up with the idea of using the exhaust gas from his diesel engine to drive a turbine to compress air and "supercharge" the intake side of his old knocker. As a result of Bchi playing with turbines instead of making cuckoo clocks, turbocharging has become almost commonplace in the world of big diesel-engined commercial vehicles and normal practice at the performance end of the market, but it has yet to make any sort of real mark in the world of production motorcycles.
Over-the-counter turbochargers have been available for big four-cylinder bikes for years, but these bolt-on performance kits are only as good as the amount of work needed to make them work properly and harmoniously with the engine. Honda, Yamaha, Kawasaki and Suzuki built turbocharged motorcycles in a mad fit of 1980s one-upmanship, and the corporate war between the giants spawned a trio of technically over-complicated and bizarre bikes...and the world's first successfully turbocharged production bike.
Honda was the first into the fray with a turbo version of its CX500, and the bike that launched a million yawns was pretty useless. Yamaha also had a fairly bland contribution-the XJ650. Suzuki had another key to the comatose cupboard in the form of the XN85-a motorcycle that had very little to offer either.
After the other three shot their corporate bolts, Kawasaki jumped out of its pajamas and gave them a severe kick where it counts with the GPz750 turbo-the only real production turbo offering sport ability and street cred. The turbo Kawasaki was the best of the bunch-a bike with the aesthetics and menace of a switchblade and a simple, effective and compact turbocharging system that would howl along at 140 mph and knock out standing quarter-mile times in the high 10s.
The turbo fad quickly wore out, though, and the manufacturers focused on race replicas as their flagship performance models instead of gimmick bikes. Since those days, the private sector has picked up on turbocharging, and it's trickled down from strip racers to street riders.
But how do these wild contraptions actually work? The function is rather simple, but getting a durable application can be a bit tricky. A conventional motor's ability to produce horsepower is dependent upon the rate at which the engine can burn the fuel and air mixture that is fed to it by injectors or carburetors. A turbocharger is a device designed to increase the mass of airflow into an engine and therefore increase the engine's capacity to produce power. In other words, a turbocharger is a mechanical pump designed to force-feed more air into the engine; more air means more fuel burned, which equates to more power. But that has a downside-the by-product of more heat puts more strain on the mechanical parts of the engine.
Leaving the financial facet of the equation alone for a minute, turbocharging is a way of getting something for nothing. The gas exiting the exhaust system is fast and hot, and following its exit into the atmosphere, it serves no useful purpose at all other than upsetting your yogurt-and-sandals neighbor at 3 a.m.
The role of a turbocharger is to harness this stream of wasted energy to produce more horsepower from within the engine. In effect, a turbocharger is driven off the energy generated by the flow of exhaust gas, whereas a supercharger is mechanically driven from the engine by way of belts, chains or gears and therefore uses power from the engine to create even more power. A turbocharger, however, is basically a turbine driven by the engine's exhaust gases that produces more power without sapping any energy from the engine.
A typical turbocharger is made up of three basic components: a turbine housing, a bearing housing and a compressor housing. The exhaust gas spins the turbine, which then spins the shaft that is lubricated in the bearing housing. The shaft then spins the impeller inside the compressor housing, thus compressing the incoming fuel and air mixture before delivering the mixture to the cylinders.