One of many definitions, but lifting a load can be considered a force in a rotational direction, given the angle of the applied lever and all.

Torque - Wikipedia, the free encyclopedia has a real good definition that will probably tell you more that you wanted to know!

 

Yep, we all have pet peeves.

You would hate being in my work group. Engineers make up new words daily and can't spell 50% of them. Favorite practices are combining two words into one (workgroup, fitup) and adding "escence" or "ability" to the end of a technical term. It's like the white collar parallel to inner city ebonics.

 

In the context I used, yes. Editted by moderator krewat - removing slurs

Editted by moderator krewat to remove political reference

 

horsepower is how fast you hit a building, torque is how far you take it with you.

 

Hey Spike, how's about not getting this thread locked, so we can keep on talking about horsepower and torque and stuff?

Thanks...

 

LOCKED? How about BANNED for what he did?

It will not be tolerated.

It's been removed.

 

Here's my take on it, even though others have already brushed on it, put into terms that I think make more sense.

Torque is like Mark said, a twisting force. Put a lever on shaft, one foot long, sitting level (parallel with the ground). Put 1 pound at the end, that's ONE FOOT POUND of torque applied to the shaft.

If it's not moving, it's not doing any "work". If you put a wheel, one foot in radius (two feet in diameter) on that shaft, and apply one foot pound of torque, and the entire assembly weighs one pound, you get ONE GEE (1g) of acceleration. (Ignoring friction, drag, etc) Keep applying one foot pound, no matter the RPM, you get ONE GEE of acceleration forever.

(Forgetting for the moment about the speed of light constant, the slowing of time as you approach that speed, and every other bit of physics involved).

Now, apply one foot of torque to a shaft spinning at 5252 RPMS. That's ONE HORSEPOWER. If it were spinning at 100RPMs, that's only 0.019 HP.

Double the RPMs to 10504RPMs, OR double the torque to 2 foot pounds, that's TWO HORSEPOWER.

HP=TORQUE*RPM/5252

However, it gets more complicated than that. (har har hardee har har)

Let's say you have a chassis dyno, that uses a fixed-weight drum, and the vehicle spins up (accelerates) that drum at a certain speed, you can infer the amount of torque applied to the rear wheels. Using that amount of torque, and the current engine RPM, you can compute the horsepower. Notice I said "infer".

Because you are using acceleration as a way to measure torque, anything that makes the vehicle accelerate the rear wheels faster will effect that measurement. Lighter wheels, lighter driveshaft, lighter crankshaft, removing a mechanical fan, all sorts of things will affect that torque measurement.

In real actual terms, horsepower is just the amount of torque, multiplied by the RPMs, and divided by a constant (5252).

In terms of what the automobile industry defines as "horsepower" it kinda sorta means acceleration. Which it isn't.

Again, to explain better, take an example of a 1HP electric motor running at 1800RPMs. It puts out 2.9177777 foot pounds.

A different 1HP electric motor running at 3600RPMs will only put out 1.4588888 foot pounds.

BUT - if you double the gearing, that 3600RPM 1HP motor will do the same "work" as the 1800RPM 1HP motor. But the slower spinning motor puts out twice the torque. (Again, ignoring all sorts of things, like the 3600RPM 1HP motor will be smaller, and take less electric being more efficient - which is why gear-reduction starters (peanut starters) work the way they do - they take less power to spin them, but they spin twice as fast if not more and are then gear-reducted down - producing more torque than the standard direct-drive starter).

All things being equal, especially gearing and weight, the 1800RPM motor will accelerate a vehicle faster than the 3600RPM motor. Even though both are called "1HP" which sorta means they SHOULD do the same "work". But they don't.

It's a complicated thing. It's really simple in it's basics, but the term "horsepower" when it comes to vehicle engines has been *******ized to mean something else.

 

What the hell did I miss? And how could a talk about HP and TQ turn into something racial?!

Anyway...
Torque is actual Force.... Torque is what you feel... So this is the actuall force that the motor puts down... very important. (why you feel it)

Horsepower is a calculated number for work done.... so in essence this number is important because its about how much work the engine can do. Higher HP means the motor is capable of more work.

A dyno only measures torque and calculates horsepower based on the force the dyno reads.

HP = ( Torque * RPM ) / 5252


WHEN YOU DRIVE YOU ARE ACCELERATING AT THE EXACT RATE OF YOUR TORQUE CURVE.... you are at max accelleration at your torque peak. PERIOD.


Watt came up with HP he decided that 1HP is equal to 33,000 ftlb/minute.
so... ft lb is one pound over one revolution one foot from the center of revolution.

[one pound one revolution is (Pi * 2) : the one pound weight is one foot from the center so one revolution makes a 2 foot diameter for Pi*2.]

Pi*2 = 6.2832 which is the amount of work we did for one pound for one revolution.

so we divide the amount of work in one horsepower by the amount of work for one revolution of one pound and we get 33,000 FT LB per Revolution / 6.2832 FT LB which equals 5252 Revolutions.

so one ft lb of torque at 5252 RPM equals 33,000 ft lbs / per minute of work.

or 1 HP = (1 ftlb of torque * 5252 RPM) / 5252

horsepower is just calculated, thats it.... but it is important as its the work that can be effectively done by the engine.

For a driver Torque is all that matters. 300ft lbs of torque will give you the same acceleration at any rpm whether 2000 or 4000, if you have 300 ft lbs at that point, thats how fast you will accelerate. but if you were calculating HP.

Car 1 ---- 300ftlb of torque at 4000 rpm = (300ftlb *4000rpm) / 5252 = 228HP
Car 2 ---- 300ftlb of torque at 2000 rpm = (300ftlb *2000rpm) / 5252 = 114HP

here is the important part... each of these cars is accelerating the same when car 1 is at 4000 rpm and car 2 is at 2000 rpm.

so if they were both lined up car 1 at 4000rpm and car 2 at 2000rpm in the same gear, they would take off at the same acceleration [ all other things aside like weight gear ratios, driveline pwer reduction, etc....].....the only difference is that 300 ftlb of torque over 4000 rpm is considered more work due to the distance of 4000 revolutions per minute...


IT HAS NOTHING TO DO WITH ONE GETTING YOU GOING AND ONE KEEPING YOU GOING... TORQUE DOES IT ALL.....

YOUR TORQUE IS YOUR ACCELERATION... more acceration due to more torque. if that torque stays high at higher rpms then it will also mean more horsepower, but its about the area under the torque curve.. it doesnt matter about the peak numbers its about area under the curve the more area the more acceleration.

if a car has a peak of 400 ft lb of torque but averages 200 it will be slower, much slower than a car , that has a peak of 350 but averages 300.... because it will have an average of 100 more ft lbs of torqe and acceleration from idle to redline.

 

This is gonna get very confusing for everyone hahah

 

Holy crap, someone else gets the "area under the curve" concept.

 

Ya.... that is why i think the best way to understand this is by looking at dynos. It just makes so much more sense.

 

Because all these tuner companies (not matt w/spartan) just show peak numbers. Well peak numbers look great on paper, but peak numbers do nothing on the street! I wish we could get matt to chime in... since he is a genius with this stuff.

 

I would add that what matters is rear-wheel torque, that's what actually drives the car. And of course, it will be MUCH higher than the engine torque, actually the engine torque times the total gear ratio, ignoring drivetrain losses.

But, in any given gear, the shape of the rear-wheel torque curve should be the same as the shape of the engine torque curve, so the actual and percieved acceleration curve will be the same "shape" as the engine torque curve.

Interesting point you made there Mr. Playa.

 

Thanks for dealing with that, Krew.

 

Ya gearing plays a huge roll in a car/trucks performance. Although engine torque will never change, torque at the wheels can!