There is no topic more contentious on motor-vehicle forums than that of ‘power vs torque’, with both sides having very vocal adherents. There is also a great deal of misunderstanding about torque and its role in vehicle acceleration. Here's a sampling of various statements on torque:
- ‘The NC700 is a faster bike than the CB400, even though it has the same power, because it has twice the torque.'
- ‘It is a far more tractable ride, because of the engines torque characteristics. That makes it easy to ride in traffic.’
- ‘More torque means you have to be much smoother with the throttle. Otherwise you can spin rear and go down (esp in wet).’
- ‘Horsepower is what you read about, torque is what you feel.’
These, and statements like these, have been repeated for so long that they've almost taken on the nature of 'statements of faith'. You see a lot of discussion comparing the horsepower and torque numbers for different bikes, and explanations calculating 'rear wheel torque' from gearing ratios. However, what you do not see are arguments that go back to fundamental physical principles, building up using mathematical explanations.
My theory is that what can usually be explained as torque is, in actuality, better described as 'power differential'. What I would like to do, through this essay, is explain my theory and back it up using mathematics and explanations that most people should be able to understand.
I'll start by talking about Energy.