What would be the improvement, if any, for a motorcycle engine using an electric turbo like the one pictured below?
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Without any information about the turbo or the motorcycle, how can we answer? Please provide some detail.– CharlieRBOct 11, 2017 at 13:45
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Probably none: youtube.com/watch?v=cbGWgvJN1_8– raydoweOct 11, 2017 at 15:29
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First thing, this question needs a lot more detail. But definitely "no" for constant use. I have considered this in the past because of the benefit of ease of install/flexibility of placement, but for constant use you're converting from mechanical to electrical back to mechanical -- and each conversion costs efficiency. This should be a comment on Ceshion's answer, which is correct, but I don't have the rep for it: However, one consideration for someone smarter than me is an electric fan's feasibility for occasional use like a nitrous system, perhaps primarily from battery.– seizethecarpOct 16, 2017 at 20:54
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1your fan (in the turbo) has to be amazingly strong to be able to get some kind of use-able boost. and to be worth it, it has to use an amazingly small amount of electricity.– agent provocateurOct 17, 2017 at 18:00
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1This has peaked my interest, and I might throw my "hat" in the ring. HOWEVER, this is NOT a turbocharger. This is an electric motor driven supercharger. In order for it to be a "turbosupercharger", it would need to have a turbine, specifically driven by the expansion of exhaust gasses due to heat (the magical A/R). I reserve the right to convert this comment into one of my old crumugeny hippie rant answers later... And "NO", it simply will not work. It is difficult for us mere mortals to understand how much energy is contained in 2000F exhaust gas, vs. a 12 volt motorcycle battery.– SteveRacerNov 8, 2017 at 4:29
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1 Answer
Having looked into this in the past, the problem with electric superchargers and why they aren't widely used is partially that doing the job of a turbo/supercharger (moving and compressing a lot of air, fast) requires both relatively high torque and relatively high speed, while not taking up much space (a consideration on motorcycles, less so on cars). Unfortunately, with electric motors, it's a "pick two" sort of situation unless you can spend a lot of money.
The other consideration is that you can't get something for nothing. If you have an electrically-driven supercharger, the several horsepower (think of it in terms of kilowatts from here on) required per psi of boost needs to come from your electrical system.
We'll estimate 3 kW (roughly 4 hp) per psi of boost. This is quite possibly less than the actual power requirement, but it illustrates the point just fine. To boost 8psi, you might need 24 kW of power. Your electrical system needs to provide all that power, plus enough to make up for losses to friction/resistance/etc. For comparison, if we take a pretty average motorcycle alternator that provides 20 amps/14 volts peak, you end up with 280 W. Not kilowatts, just watts.
When driving a turbo/supercharger off the engine, this is fine as your loss for providing boost is made up for by your power increase. However, as you can see from that line of thinking, you need to be able to provide a serious amount more electrical power than the bike is actually capable of to drive an electric forced induction system.
That said, if you were serious about it and believe you could engineer the losses to a minimum, you probably could pull a lot more power away into the alternator to drive the motor for the supercharger (by replacing the alternator/generator with a much, much more powerful one), but it would not be a simple feat by any means. In fact, "turbos" like the one you have posted in the picture are little more than a fan and will likely slightly reduce wheel horsepower by drawing more power from the alternator and not giving a significant increase in power in return.