Torque vs. HP Revisted

[lovehamr]

Sounds to me like Olddog, Tommy and Scottj are the only ones with really a firm grasp on this. Every now and then someone pops up with that same argument and truth be told we'd probably all be better off using the aussie's expressions in watts. But since that wasn't really on the table, lets look at the euphemisms vs. math thing again. Some of this has already been covered but lets go a little deeper.

These are misnomers;
“You feel torque from the seat of your pants much more than you feel horsepower."
"Torque gets you off the corner."
"Torque is more important that HP."

The human butt can no more distinguish torque from HP than it can blue light from red light. In simplest terms we are dealing with power or energy, a force that moves you. These forces are expressed in mathematical terms thusly;

1 HP = 33,000 foot-pounds per minute
Or it could be P/hp=[T/(ft lb)][w/(r/min)] over 5252
By the way, that 5252 is why all dyno charts show the HP and torque curves crossing at that RPM.
Or it could be 746 watts
Or maybe 2,545 BTUs (British thermal units)
One BTU being equal to 1,055 joules, or 252 gram-calories or 0.252 food calories.
This means that 1 HP is also equal to 2684975 joules, or 63504 gram-calories, or 641.34 food calories
Presumably, a horse producing 1 horsepower would burn about 641 Calories in one hour if it were 100% efficient.
The point is that its energy, a force, what moves you, not some nebulous calculation.

Torque is the force applied to a lever, multiplied by its distance from the lever's fulcrum in our case a theoretical lever and a rotating fulcrum, or more simply:
T = r x F (whadaya know another calculated theoretical number)
Which is linier force multiplied by a radius. Of course this formula always assumes a perpendicular force axis to the fulcrum.

To put this into perspective the next time you want to accelerate really fast try shifting at your engine’s torque peak (for many of us it's around 3500 rpm) rather than the HP peak (say 5800 rpm or maybe even 7000 if you have a lot of race kit). It doesn’t take a rocket scientist figure out using which shift point will accelerate the vehicle faster. This is because we’re talking about energy expended over time not a static applied force. To say that another way; I could put 84 pounds (that’s my Buell's peak output) of torque on your MC crank shaft with a ratchet handle, but I don’t think you’re going to accelerate too quickly and I doubt that you’d feel it too much in the seat of your pants either.

Suffice to say that your engine is a pump and the faster that it can turn and make power within the constraints of VE then the faster you're going to go regardless of whether you measure that output in torque, HP, watts, joules, calories, BTUs or warp factors.

Steve