Quote:
Originally Posted by charles roybal
"First of all, from a driver's perspective, torque, is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same"
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I just can't help it, maybe it's all the math classes, I don't know, but every time I see one of these "it's all about torque" rants I just have to break it down. This is a misnomer; “torque, is the only thing that a driver feels" and then follow that up with "horsepower is just sort of an esoteric measurement"??
I got news for ya, 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 best expressed in mathematical terms (rather than internet colloquialisms) 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 "esoteric" calculation.
Torque, on the other hand, is a static 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 "esoteric" number)
Which is linier force multiplied by a radius. Of course this formula always
assumes a perpendicular force axis to the fulcrum. And we all know that this is NOT the case in a reciprocating engine right?
To put this into perspective the next time you want to accelerate really fast try shifting at your engine’s torque peak rather than the HP peak. It doesn’t take a rocket surgeon to figure out using which shift point will accelerate the car faster. This is because we’re talking about energy expended over time (HP) not a static applied force (TQ). To say that another way; I could put 100 pounds of torque on your 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 to much in the seat of your pants either.
In summary, to poo poo on HP and bow to torque is like saying that you really like chocolate cake but that chocolate is over rated. It's disassociating 2 mathematical formulae which are expressions of force, just one is static and the other is expressed over time. And the more power you have over time the faster you go, period.
Steve
I should add Einstein and quantum entanglement not withstanding!
