Rpm vs torque and power

Barîb

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I have a little two stroke bike I’m building, and I was just wondering how rpm works vs. net power. The two stroke I’m rebuilding makes 7000 rpm while my four stroke go kart only makes 3000 rpm. The go kart engine is obviously considerably bigger and obviously makes more torque, but if geared proportionally couldn’t they make the same amount of power (as in net force output)? Can anyone explain this, it doesn’t make a lot of sense to me.
 

Snaker

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Ah your asking for a simple answer when none exists.
Go to some automotive web sites and search torque vs horsepower
Be ready for some fightin.
Without having the equipment to measure, your pretty much stuck with listed specs and your seat of pants.

Two strokes are interesting in this, dirt bike engine designers have varied flywheel weight/mass to manipulate.
MX would typically have small/light flywheels for hard acceleration (hp).
Enduro would typically have larger/heavier flywheels for more grunt (torque)

A side note: tractor data used to and maybe still does show hp at various points in the drive train.
Engine hp: straight off the engine
PTO/pulley hp: the power transferred through gearing to run other equipment.
Drawbar hp: the power transferred through gearing to the wheels pulling a load, weight and traction and hitch angles all factored in.
Those specs would be from the same machine and could be significantly different to each other.
Sometimes the torque spec would be listed from the engine, don't recall it ever listed at the other points.
 
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