Torque vs Hp

As a pretty big newbie I need some information. I wanna know what the difference is between horsepower and torque... I have been very confused because I have heard hp is 33,000 (05 55,000 I have heard both) foot pounds per minute. But torque is pound feet. I would really like to understand the difference, can anyone help me?

Torque is the actual power. It's the tug that you feel pull your butt when you floor it. Torque is the only power that an engine actually makes. HP is a calculated number. You can't feel it, but it's very important to acceleration. Torque is like the brute power that gets things moving and HP is like the continued pulling effect. It's hard to explain really.

On average, the displacement(stroke actually) of an engine gives you and idea of the torque output and the redline gives you an idea of the HP output in proportion to the torque.

Example:
Dodge Viper 8.0 liter engine.
450hp@5200rpm
500tq@3700rpm
Redline@5500rpm

Honda S2000 2.0 liter
240hp@8300
153tq@7500
Redline@9000

The viper engine, with the longer stroke, make much more torque than hp but in turn can't rev very high.
The S2000 engine on the other hand, with such a short stroke, can rev extremely high. The short stroke, however, makes for weak torque.

i will make a chart..

_______lb./hp__torque__daily driver_1/4 mi___twisties_____other

spec-V:__ok____ok_____great______ok______good_______che ap

truck:___bad___great___good______bad______bad_____ __towing

f1:_____great___bad_____bad______great___great____ uber high redline

viper:___great__great____ok_______great____bad____ _tire-spinning

sti:_____great__great____ok_______great____good___ __slight lag


in conclusion.....turbocharge your sport compact or buy an STI.
and this concludes my drunken, sleep-deprived lecture on horsepower and torque.

thank-you

fugiot explained it very well

Look at a dyno chart, pick an RPM, look at the torque number for that rpm and multiply that number by whatever RPM it's at and divide it by 5252...you have horsepower.

Torque X RPM /5252= Horsepower


Now, don't do the noob mistake by calculating peak torque and peak rpm, you'll get the wrong number. Just do it the way I told you to.

Torque vs Horsepower??? I remember asking myself that question when I first bought my Spec V. Here's a simple explanation that i came up with. Torque is the rate of acceleration that your car has. The more torque you have the harder and faster you will accelerate. Horsepower is how long you can accelerate for. A car that has a lot of horsepower but less torque will accelerate longer than a car with more torque than horsepower. For example the Spec V has 180ft-lb TRQ @4000rpm, 175HP: The RSX-S has 142ft-lb TRQ @6000rpm, 200HP. The Spec V will accelerate faster because of the higher torque but the acceleration will only last until it's HP peak of 175@6000rpm. The RSX-S will not accelerate as fast due to the lower torque but it will keep accelerating until it's HP peak of 200@7800rpm. The Spec V can not rev that high because most of it's acceleration is in the low end of the RPM range. The acceleration in the RSX-S is in the high end of the RPM range due to it's higher reving engine. I hope this makes sense. Remember, the Spec V will pull harder, but the RSX-S will pull longer. Short distance race, the Spec V has the edge. In a longer distance race, the RSX-S will win.

Torque vs Horsepower??? I remember asking myself that question when I first bought my Spec V. Here's a simple explanation that i came up with. Torque is the rate of acceleration that your car has. The more torque you have the harder and faster you will accelerate. Horsepower is how long you can accelerate for. A car that has a lot of horsepower but less torque will accelerate longer than a car with more torque than horsepower. For example the Spec V has 180ft-lb TRQ @4000rpm, 175HP: The RSX-S has 142ft-lb TRQ @6000rpm, 200HP. The Spec V will accelerate faster because of the higher torque but the acceleration will only last until it's HP peak of 175@6000rpm. The RSX-S will not accelerate as fast due to the lower torque but it will keep accelerating until it's HP peak of 200@7800rpm. The Spec V can not rev that high because most of it's acceleration is in the low end of the RPM range. The acceleration in the RSX-S is in the high end of the RPM range due to it's higher reving engine. I hope this makes sense. Remember, the Spec V will pull harder, but the RSX-S will pull longer. Short distance race, the Spec V has the edge. In a longer distance race, the RSX-S will win.

That's a bad way of thinking about it, basically because it's completely wrong

Torque - The physical twisting force that your pistons exert on the crank and is transmitted to the wheels
Horsepower - The rate that this torque can be applied. If you hit a nail with a hammer twice, you put the same force on the nail as hitting it once, but by hitting it twice you do more work and the nail goes into the wood farther. Same thing with engines, even if your car makes the same amount of torque at 2000 rpm as it does at 4000 rpm, it will accelerate faster at 4000 rpm because that torque is being applied twice as often.

This is why high revving cars have higher horsepower than torque, because all they need to do is carry that torque up to a higher rpm, and they instantly make a LOT more horsepower, even though they don't need to add any power adders to the engine. Low revving cars can't make that much horsepower, because they can't rev high enough to put their high torque output to good use. Look at the equation integra posted, that's the formula for horsepower. You can see that if a car never revs past 5252 rpm, it's horsepower will never be greater than the torque because it just can't rev high enough to really get the pistons moving and do a lot of work. On the other hand, if the car can manage to rev to 10,504 rpm, it's horsepower will be twice as large as the torque (at that rpm). This is where companies like Honda shine, they don't need huge engines to get the power, all they do is take a small engine that makes a decent amount of torque, and they give it the ability to rev much higher, this puts that limited torque to good use and it really gives them a buttload of horsepower. Horsepower is what you feel when you push the gas, not torque. If you floor it at 5000 rpm it will pull a LOT harder than at 2000 rpm, even though it makes the same torque at both spots (in the spec atleast). The difference is that at 5000 rpm you have 2.5 times more horsepower than you do at 2000 rpm.

Torque vs Horsepower??? I remember asking myself that question when I first bought my Spec V. Here's a simple explanation that i came up with. Torque is the rate of acceleration that your car has. The more torque you have the harder and faster you will accelerate. Horsepower is how long you can accelerate for. A car that has a lot of horsepower but less torque will accelerate longer than a car with more torque than horsepower. For example the Spec V has 180ft-lb TRQ @4000rpm, 175HP: The RSX-S has 142ft-lb TRQ @6000rpm, 200HP. The Spec V will accelerate faster because of the higher torque but the acceleration will only last until it's HP peak of 175@6000rpm. The RSX-S will not accelerate as fast due to the lower torque but it will keep accelerating until it's HP peak of 200@7800rpm. The Spec V can not rev that high because most of it's acceleration is in the low end of the RPM range. The acceleration in the RSX-S is in the high end of the RPM range due to it's higher reving engine. I hope this makes sense. Remember, the Spec V will pull harder, but the RSX-S will pull longer. Short distance race, the Spec V has the edge. In a longer distance race, the RSX-S will win.

I did'nt read your whole post, but I wanted to reply quickly befoe I forget what I was thinking.

You've got everything backwards. torque is not the rate of acceleration the car has, because if 2 cars with the same weight but differant torque race, the one with the more torque won't win, the one with the most HP will. **Of course thre are exeptions, and I know someone will reply that they beat a car with the same horsepower just because they have the same torque, some races are wierd. I beat a car that's 300 LBS lighter than mine, but we both have the same exact engine ( b18c1)*** Anyways, horsepower is not how long you'll accelerate...thats RPM. you won't accelrate faster if you have alot of torque...you'll accelerate faster if you have torque thats matched to a decent RPM range, then you'll have horsepower, read the post I made before you then you'll get what I'm saying.

My car is 170 HP, 128 LBS of torque, The new S.E.R.s are 170 HP and like 160 LBS of torque, both cars are similar in weight, but I've raced ALOT of stock SERs and I've beaten most of them.

The Spec V might not rev alot, but it's given a 6 speed for a reason :p


P.S I beat Spec Vs, I get smoked by RSXs. Torque does'nt matter unless it's matched by a a decent RPM range....read the post I made before you.

p.s.s I PISS ON TORQUE.

Horsepower is what you feel when you push the gas, not torque.

I disagree. Torque is the only power that you can feel. Like you said, It's like a hammer hitting a nail with a certain amount of force. Just because you hit the nail more frequently(such as revving high) doesn't mean that the force increases. You're just doing more work in a smaller amount of time. Not more powerful work. The illusion of noticing that the car accelerates more quickly in the higher rpms might contribute to the feeling that you're getting pulled harder but you're actually not.

So you're saying the car (assuming both cars are equal) with the higher torque number will win?


Damn, I feel like all my previous posts are bieng ignored.

The Spec V might not rev alot, but it's given a 6 speed for a reason

a spec-v doesn't need a six-speed nearly as bad as say, a celica gts.
this is why torque is important - in a spec-v you don't need to be in the optimal gear to get decent acceleration, whereas in a celica gts you have to be in "lift" to move.

torque:
-gets you off the line faster
-is a better daily driver
-allows for more mistakes

horsepower:
-wins 1/4 mi. drag races

My car is 170 HP, 128 LBS of torque, The new S.E.R.s are 170 HP and like 160 LBS of torque, both cars are similar in weight, but I've raced ALOT of stock SERs and I've beaten most of them.

well despite your incorrect stats, it is a good point. curb weights are pretty even, and to the wheels, you get more horsepower than a SER. since you say you usually win, it shows that horsepower to weight ratio is really the only important factor in drag racing.
i bet the SERs got you off the line tho :wink:

a spec-v doesn't need a six-speed nearly as bad as say, a celica gts.
this is why torque is important - in a spec-v you don't need to be in the optimal gear to get decent acceleration, whereas in a celica gts you have to be in "lift" to move.

torque:
-gets you off the line faster
-is a better daily driver
-allows for more mistakes

horsepower:
-wins 1/4 mi. drag races



well despite your incorrect stats, it is a good point. curb weights are pretty even, and to the wheels, you get more horsepower than a SER. since you say you usually win, it shows that horsepower to weight ratio is really the only important factor in drag racing.
i bet the SERs got you off the line tho :wink:

I agree with you on your view of torque and HP, but where are my stats incorrect? SER's are fast off the line, I'll admit that, but the more I'm on the gas, the more I pull on 'em. SER's need to be uncorked, thier stock intake/header/exaust is very restrictive, they're great cars tough, I love 'em.

I agree with you on your view of torque and HP, but where are my stats incorrect? SER's are fast off the line, I'll admit that, but the more I'm on the gas, the more I pull on 'em. SER's need to be uncorked, thier stock intake/header/exaust is very restrictive, they're great cars tough, I love 'em.

The SE-R has 175hp and 180lb-ft. That's all that you had wrong. :smokin:

Torque is a measure of rotational force similar to LBS and Newtons as a measure of force...

It's broken into T = (rotational inertia of a mass) * (angular acceleration of the mass).

So the more torque you have in a car the faster the driveshaft is accelerating which translates into the faster the wheels are accelerating and hence the car is accelerating.

Horsepower is a measure of power, given by (work done) / (time)

Since work = (torque) * (change in angle [shown by your RPM] ) the higher your redline is as well as the higher torque you have the higher your horsepower will be.

Then HP = (torque * change_in_angle) / (time)

So basically

Higher Torque = Higher HP
Higher Redline = Higher HP

HP is dependant on Torque due to the equation of Work. So to me it seems that torque is the more fundamental (if not more important) spec to look at. More Torque means you're accelerating faster and you'll have higher horsepower. I don't know the intricate workings of cars but it doesn't seem that you should accelerate drastically different if you're at 20 mph or if you're at 100 mph, except for the difference of gear ratios.

college physics at it's sloppiest. lol. It should basically be correct but i'm in a rush and i'm not checking over everything. :)

And remember, Torque and Horsepower and everything is a mathematical and numerical representation of what you're car is doing. Performance decides numbers, not the other way around.

HP is dependant on Torque due to the equation of Work. So to me it seems that torque is the more fundamental (if not more important) spec to look at. More Torque means you're accelerating faster and you'll have higher horsepower. I don't know the intricate workings of cars but it doesn't seem that you should accelerate drastically different if you're at 20 mph or if you're at 100 mph, except for the difference of gear ratios.

HP=T(RPM)/constant

Torque is not as important as RPMs in the above equation, because RPMs are in the thousands while torque is in the hundreds.
I.E. Formula One cars have small (relative to other racecars) NA engines and therefore do not have much torque. But, they are faster than everything else because they rev to 18,000 RPMs and make 900 HP. Their relatively small engine also enables them to be light.
So the ideal race car actually does not have torque.

As for that last part up there, the reason cars are slower at high speeds is due to drag.

It's broken into T = (rotational inertia of a mass) * (angular acceleration of the mass).

So the more torque you have in a car the faster the driveshaft is accelerating which translates into the faster the wheels are accelerating and hence the car is accelerating.

well put.

You know, that does make sense. So I had it all wrong and so did SR20DE4EVR. Thanks for clearing that up.

Go back to your go-kart days. A large chain sprocket makes for a slower speed but a better hill climber. A small sprocket gives you faster speeds but is lousy when climbing hills.
Same theory goes for engine stroke as mentioned by fugiot.
So what are you trying to do swoop some hills or mash the gas? torque-hp you decide

I disagree. Torque is the only power that you can feel. Like you said, It's like a hammer hitting a nail with a certain amount of force. Just because you hit the nail more frequently(such as revving high) doesn't mean that the force increases. You're just doing more work in a smaller amount of time. Not more powerful work. The illusion of noticing that the car accelerates more quickly in the higher rpms might contribute to the feeling that you're getting pulled harder but you're actually not.


I see your point, but accelerating faster at higher rpm is not an illusion. Why do we rev to the redline when racing? The qr25 has a flat torque curve straight from 2000rpm to 5000rpm (or thereabouts). If torque really was the only thing that mattered in acceleration, someone shifting at 3500rpm would run the 1/4 in the same amount of time as someone shifting at redline because they would both be making the same amount of torque the whole time (actually the person shifting at 3500 would be making more torque, since at redline the torque drops off dramatically). I think we can both agree that the person shifting at 3500 would loose terribly, but why is that? Gear ratios have nothing to do with it (the person shifting at 3500 would be in a higher gear), obviously it's not a difference in drag since the person shifting at 3500 would actually be going slower and have less drag. The only difference is the amount of horsepower that the cars are making at any given point in time.

When you want to accelerate on the freeway, you downshift, but why? You make the same amount of torque at 3000rpm as you do at 5000rpm, the difference is in that lower gear your rpm is higher and you make more horsepower, which makes you accelerate faster.

I think I see your point, but if you take a car that revs high (say 8k rpm) and only produces 150hp against a car that revs low (say 6k rpm) and produces 250 hp and apply it to your theory wouldn't that mean the car with 150 hp would win? Or is it a matter of power curve and when?

I think I see your point, but if you take a car that revs high (say 8k rpm) and only produces 150hp against a car that revs low (say 6k rpm) and produces 250 hp and apply it to your theory wouldn't that mean the car with 150 hp would win? Or is it a matter of power curve and when?

the 250 hp car would win. horsepower is all that matters.

if you have 250 hp at 6k then you must have a lot more torque (at 6k) than the guy who has 150 hp at 8k. so in a sense, it is important that he has torque. but only because it allows him to make 250 hp at 6k.... get it?
what sr20 is saying is that TORQUE at low rpms must be a lot higher to get the same horsepower as the high rpms. in our car (and most cars), the horsepower curve just goes up all the way up to redline. torque is max at 4k but that is not max horsepower because you only need a fraction of that torque at 6k to get more horsepower.
i.e. we might have the same torque at 3k and 5k but clearly more hp at 5k.

I think I see your point, but if you take a car that revs high (say 8k rpm) and only produces 150hp against a car that revs low (say 6k rpm) and produces 250 hp and apply it to your theory wouldn't that mean the car with 150 hp would win? Or is it a matter of power curve and when?

no not at all, I was comparing the same car vs itself, just at different rpm. When you start comparing different cars you get much different results. All I was saying is that in the spec, you have the same torque at 3k and at 5k, but at 5k you have a buttload more hp, which lets you accelerate faster, exactly like what fry_ed said. If you have a car that makes 250hp @ 6k, it will obviously beat out a car with 150hp @ 8k. I wasn't saying that rpm wins battles at all, I'm just saying that if you have 2 cars with the same amount of torque, the one that can carry this torque up to the highest rpm will win, assuming they have similar gearing, weight, etc, because it will have more horsepower at that higher rpm. If you have a car that has dramatically less torque, even if it can rev 2k higher, that's not nearly enough to get enough hp to make up the difference. If you could get that car to hold that amount of torque out to say 12k rpm then it would have more hp than the other car and would win (in a long enough race, in a short race the other car would be able to pull at first since the 12k car would have to reach 30-40mph before the hp got high enough to match the lower revving car).

I see your point, but accelerating faster at higher rpm is not an illusion. Why do we rev to the redline when racing? The qr25 has a flat torque curve straight from 2000rpm to 5000rpm (or thereabouts). If torque really was the only thing that mattered in acceleration, someone shifting at 3500rpm would run the 1/4 in the same amount of time as someone shifting at redline because they would both be making the same amount of torque the whole time (actually the person shifting at 3500 would be making more torque, since at redline the torque drops off dramatically). I think we can both agree that the person shifting at 3500 would loose terribly, but why is that? Gear ratios have nothing to do with it (the person shifting at 3500 would be in a higher gear), obviously it's not a difference in drag since the person shifting at 3500 would actually be going slower and have less drag. The only difference is the amount of horsepower that the cars are making at any given point in time.

When you want to accelerate on the freeway, you downshift, but why? You make the same amount of torque at 3000rpm as you do at 5000rpm, the difference is in that lower gear your rpm is higher and you make more horsepower, which makes you accelerate faster.

Right, I stated it wrong. You do get pulled harder but you can't feel more power at a higher rpm. You just feel the same amoubt of power more frequently. Which is the"illusion" I mentioned.