EMotor<-->ICE Equivalency

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Jun 29, 2022
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First post here, but I've been lurking for the past two weeks brushing up on build threads. I'm planning a build and am just beginning to start spec'ing components. I was hoping to find some kind of rough EMotor:ICE functional equivalency guidelines, but so far, no luck. Do any veterans here know where I might find such information?

Barring that, does anyone have advice for how to approach spec'ing an EMotor to roughly match a particular ICE? I know that power isn't everything, and I get the sense that if I matched peak power of the EMotor to the original ICE, I'd have a wildly overpowered feeling motorcycle on account of how power and torque are delivered.

More specifically, I'm on the hunt for a suitable powerplant for a '57 Enfield Bullet 350. I'm hoping to do the original bike justice, so I'd like to have it feel the same or better than it did in its heyday. Am I right in thinking a ~4kw (edit: *continuous power) motor would be in the right ballpark?

Really appreciate the help. I'll be sure to start a build thread as soon as I have some pictures worth taking.
 
Well, there isn't exactly an equivalent becuase they don't work quite the same way, and torque/rpm curves will be different, etc.

You can guesstimate power equivalent in that 1hp is defined as 750w, but in reality it isn't just the watts (or the hp) that makes a system perform a certain way.


Are you looking to just replace the ICE with an electric motor, and still use whatever transmission and drivetrain the bike may have?

Or are you looking to replace the entire ICE system with electric, such as a hubmotor in the wheel, leaving all of the chassis space for batteries?


You should also decide on and list the usage scenario: How fast do you want to go, and how far do you want to go at that speed, under what conditions (terrain, hills (what slope, how long, etc), wind, road conditions, etc), riding style (stop start traffic, continuous riding, slow acceleration, wheelies, etc)?

What you want it to do will determine the kind and power level of motor and controller you'll need, and how long you want it to do that, plus the power level of the system, will determine the battery you'll need.

I recommend looking at other motorcycle conversion threads here to get a sense of what they needed to do for their purposes.

There is also the http://ebikes.ca/tools/simulator.html, which while designed for bicycle-level systems, can be customized for whatever level system you want to simulate, to get guesstimates of what different systems may do for you.
 
Your original engine made 20hp at the crank.

An EV setup capable of 15-18kW peaks and say 5-6kW continously would be a nice place to be.
 
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