Supercharging it

I read the column in Motorcycle Sport & Leisure regarding supercharging pros and cons. It’s obviously a complex issue and outside of my expertise!

Nevertheless, looking at the current development of electric and hybrid vehicles I wonder if...

How about providing power to the supercharger using an electric motor?

Instead of the impeller relying on the engine speed, the rpm could be set at a fixed rate, which would provide constant pressure from the moment ignition is engaged.

Also, no drag on the engine and once running it can be powered by the alternator.

There are some very clever engineers in the motorcycle industry. Perhaps you could pass my email on to one of your contacts? Steven Burton

Electric supercharger/turbo systems have been used for cars, which have an electric system that is efficient at low engine rpm/low load range to start from zero, and it normally works in a short time.

Electric supercharger is efficient especially at the low end of the rpm range, where the electric charger system can compress air by 3-4kW power, but charger assist time is limited by limited battery size.

For motorcycles, Kawasaki has a very different purpose and approach with using a supercharger than cars. Therefore the Ninja H2 and H2 SX are using mechanical superchargers. This system can provide superior additional power, especially at high engine rpm/high load range.

This makes it possible to run the system for a long time by using its high-charged power, specially for sports riding.

The H2 and H2 SX’s mechanical supercharger compresses the air and creates 4kW of power at below 8000rpm – this is not horsepower, this is driving power for the supercharger.

But at the max load range, this system can offer 20-30kW power to compress the air and send a huge volume of air to the engine to generate superior power, and an engine feeling that you cannot get from a normally aspirated motorcycle engine.

From the system weight view point, if we put the 30kW powered electric motor and its power supply (battery) to make the same compression power with the H2’s supercharger, the system would be getting bigger and heavier, making it impractical for a motorcycle.

If the system keeps the charger on, then the battery would be draining, making it impossible to use it for a prolonged period.

Or you would need an additional big generator to charge the battery, but then the bike would be getting heavier again.

Because of these reasons, Kawasaki didn’t select the electric supercharger, but developed the H2’s mechanical supercharger in-house.