Re: Torque v/s rpm relationship

I assume you are asking about gasoline (Otto cycle) internal combustion
engines. For the ideal cycle, the torque is a constant throughout the
range of speed and is independent of the engine speed, while the power is
directly proportional to the engine speed. For real engines, there is some
effect from speed-sensitivity, especially at either end of the
range. However, the trends are essentially the same: torque vs. speed is a
rather flat curve with a relatively early maximum, while power vs. speed
has a sharper peak and the peak occurs at a higher speed than does the
torque curve. Do not trust the tabular type of data given by the
manufacturers - it is incomplete information. It is far better to look at
the performance curves through the range of operational speeds.
A good reference on this is Energy Conversion by Weston.
I hope this helps.

Frederick J. Carranti, P.E.