convert 200hp gas engine to 2 lightweigt electric motors (not hybrid)

[bucklebutt]

I am trying to find out how to best convert the power of a gas powered 200 to 300 hp auto-type engine to one or two electric motors. The size and weight are of major importance … the less the better. I am looking for something similar to a hybrid electric car, but without the batteries. Everything I have found so far deals with eco-minded, hi-mileage hybrids that have auto type performance (but rely on batteries), or ship and train engines. The electric motors do need to idle but are mostly kept at a constant speed around ½ to ¾ of their maximum output as with the gas engine. I am looking for electric engines the size and weight of a hybrid car but without the fancy stuff. The motors do not have to reverse or charge batteries. They do not have to instantly respond to power changes. Somewhere I read that converting a gas engine to electric power was about 80% to 90% efficient. Is that true and if it is, what kind of generator and electric motor is the most efficient.

 

[wayne440]

The best advice I can offer is that you should look further into whatever source you based-"I read that converting a gas engine to electric power was about 80% to 90% efficient"- on. I'm no expert on the matter, but to me that seems impossible given a practical budget. I cannot see a 250hp gasoline engine turning a generator as able to power a 200hp motor, 100hp might be a more realistic figure.

Look into diesel electric locomotives for how it is done, then scale down by 90%.

 

[LionelHutz]

Home hobbiest trying to build a hybrid?

Is this what you want?

gas motor -> generator -> electric motor

The gas engine is likely 30% to 40% efficient. Why would you expect the combination of a gas engine driving a generator to be 80% to 90% efficient?

 

[jraef]

Electric motors don't "idle" like engines, they are either on or off. But they also will only consume energy based on the applied load (minus inherent efficiency losses). You can control the speed and thus the HP output however that gets into the "fancy stuff" you say you want to avoid.

Also, the direct correlation to engine HP vs electric motor HP has more to do with torque response than HP and electric motors can deliver far better torque response to a step change in load than an engine can, so usually the electric motor can be smaller than the engine at an equivalent steady state torque output. That's been my experience anyway. I once replaced a diesel engine with an electric motor on a direct torque-to-torque basis, the electric motor smoked the belts and twisted a shaft off.

If you are planning on powering electric motors from engine powered generators, you are going to LOSE efficiency in a big way, you are better off powering directly from the engines unless the "fancy stuff" of variable speed and faster torque response is important to you.

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