The BikeSocial reporters from Bennetts have unearthed an application by BMW Motorrad at the German Patent and Trademark Office, entitled “Motorcycle with a supercharged internal combustion engine.” The technical illustrations show a superbike, based on the S 1000 RR, with an electric supercharger that blows air into the combustion chamber via an electric motor, compressor, and intercooler. This doesn’t confirm that BMW’s patented technology will make it into mass production, but it does show that the company is exploring development.
Many bolt-on electric supercharger kits you can find online don’t actually create any real compression, hence don’t genuinely result in power gains. On the other hand, well-engineered electric superchargers do have a major advantage over other mechanical forced induction systems like engine-driven superchargers and exhaust-driven turbochargers: minimal lag. Even the Kawasaki H2 series, currently the only supercharged production motorcycles on the market, are engine-driven.
Instead of sapping engine power like a conventional engine-driven supercharger or lagging after throttle input like a turbocharger, an electric supercharger could convert power from an electric motor to power the spool up, compressing air and delivering it to the cylinders. The electric motor spins at a rate proportionate to the amount of throttle applied, and its ability to be directly connected to the throttle provides nearly instant boost. Compressing air, however, requires significant energy. A good supply of power is needed for an electric supercharger to reach its full potential. Sufficient power supply is usually the main challenge for engineers.
The renewed interest in forced induction has emerged from motorcycle manufacturers having to figure out ways to provide great performance out of engines subjected to tightening emissions constraints. Some automotive manufacturers have begun using electric supercharging technology, especially in twin-charged setups, but engine management and power delivery in cars don't necessarily translate easily to compact two-wheelers. With brands taking to upsizing engines to address the issue, there’s still no replacement for displacement when it comes to motorcycles… For now.