Torque vs. horsepower
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Torque vs. horsepower
Ok, I know horsepower is derived from torque. Tq being equal, higher rpm = higher hp.
So what I want to know is, assuming torque was constant throughout the rpm band (let's say 100 tq), would you be accelerating any faster at 6000rpm than you would at 4000 rpm? The torque is the same but the horsepower is different:
HP = ((TQ * RPM))/5252)
For 100lb/ft of torque:
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
They say you're accelerating the hardest at your peak torque, NOT your peak horsepower.
So what I want to know is, assuming torque was constant throughout the rpm band (let's say 100 tq), would you be accelerating any faster at 6000rpm than you would at 4000 rpm? The torque is the same but the horsepower is different:
HP = ((TQ * RPM))/5252)
For 100lb/ft of torque:
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
They say you're accelerating the hardest at your peak torque, NOT your peak horsepower.
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Rep Power: 529 Question 2:
Say you modified your D17 to make 50ft/lb of torque at 20,000 rpm. You'd be making 190 horsepower, but you still wouldn't be accelerating very fast, right?
Say you modified your D17 to make 50ft/lb of torque at 20,000 rpm. You'd be making 190 horsepower, but you still wouldn't be accelerating very fast, right?
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Rep Power: 310 I think your Hinting at whether it is better to shift at peak torque or at redline,
So here is an article that covers some more on that topic
http://www.allpar.com/eek/hp-vs-torque.html
So here is an article that covers some more on that topic
http://www.allpar.com/eek/hp-vs-torque.html
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Originally Posted by IronFist
For 100lb/ft of torque:
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
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Originally Posted by 4jacks
I think your Hinting at whether it is better to shift at peak torque or at redline,
So here is an article that covers some more on that topic
http://www.allpar.com/eek/hp-vs-torque.html
So here is an article that covers some more on that topic
http://www.allpar.com/eek/hp-vs-torque.html
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Originally Posted by IronFist
No, I'm trying to find out why horsepower matters at all.
Gesh
Horsepower matters cuase James Watt Made up the Unit and Said it Mattered.
It's like english units .. It's completely pointless but America will never go metric.... Why ... who knows..
http://www.ideafinder.com/history/inventors/watt.htm
torque is the measure of the overall amount of work the engine is capable of (ex. towing power)
horsepower is the rate at which that torque can be applied (acceleration)
In racing applications, higher torque will get you off the line faster, but once you're moving, horsepower matters more. You have to have both. I dont know if I answered anything, but I feel special at my small tidbit of knowledge.
horsepower is the rate at which that torque can be applied (acceleration)
In racing applications, higher torque will get you off the line faster, but once you're moving, horsepower matters more. You have to have both. I dont know if I answered anything, but I feel special at my small tidbit of knowledge.
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Originally Posted by HondaLuver
howstuffworks.com
I agree, why bother to explain what came first the chicken or the egg
BTW, there is an OLD Oldsmobile saying ....horsepower sells cars, BUT Torque wins races !
Originally Posted by 4jacks
It's like english units .. It's completely pointless but America will never go metric.... Why ... who knows..
America used the metric system for the same reason we use a different rail system... during WWI or WWII we didn't want to rely on European manufacturers; esp. during time of war.
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Originally Posted by 4jacks
It's like english units .. It's completely pointless but America will never go metric.... Why ... who knows..
http://www.ideafinder.com/history/inventors/watt.htm
http://www.ideafinder.com/history/inventors/watt.htm
As Sport Compact Car says: torque is for burn outs and drag races, horsepower is for road course races.
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Rep Power: 529 All these "torque is for low end power, hp is for high end power" sayings are just there because torque being equal, higher rpms = more hp.
So obviously torque "gets you off the line" because you hit your peak tq before you hit your peak hp. If peak hp were lower than peak tq then everyone would say hp gets you off the line.
Maybe I'm just dense but no one has answered my question yet.
So obviously torque "gets you off the line" because you hit your peak tq before you hit your peak hp. If peak hp were lower than peak tq then everyone would say hp gets you off the line.
Maybe I'm just dense but no one has answered my question yet.
For 100lb/ft of torque:
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
4000 rpm = 76 hp
6000 rpm = 114 hp
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
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Rep Power: 340 well, I'll attempt to answer your Q, or more like put in my own questions/thoughts.
I have heard that torque gets you moving b/c you start at low RPMs and then HP takes over. Take a car like an S2000, not much torque, and not very happy in the lower RPMs b/c of the lack of torque. But when hitting the upper RPM's, thing accelerates........
Mmm.... i'm sure you know this, but if cars accelerated fastest at peak torque, no one would bother shifting at redline.
There are some cars with really flat torque curves, like VW/audi 5 valve engines, and BMW's 6 cylinder cars. In a comparison between an CL-S and a BMW (dont remember which 1, but had to be 3 series), the BMW out accelerated the more powerful CL. So... maybe based on that.... you can say, yes, can accelerate faster at 6000RPM compared to 4000 b/c of that flat tq curve..... maybe I'm just confused myself.......
but it's good to have a good balance of both, not just 120 WTQ and 200 WHP. ok, i'm done......
I have heard that torque gets you moving b/c you start at low RPMs and then HP takes over. Take a car like an S2000, not much torque, and not very happy in the lower RPMs b/c of the lack of torque. But when hitting the upper RPM's, thing accelerates........
Mmm.... i'm sure you know this, but if cars accelerated fastest at peak torque, no one would bother shifting at redline.
There are some cars with really flat torque curves, like VW/audi 5 valve engines, and BMW's 6 cylinder cars. In a comparison between an CL-S and a BMW (dont remember which 1, but had to be 3 series), the BMW out accelerated the more powerful CL. So... maybe based on that.... you can say, yes, can accelerate faster at 6000RPM compared to 4000 b/c of that flat tq curve..... maybe I'm just confused myself.......
but it's good to have a good balance of both, not just 120 WTQ and 200 WHP. ok, i'm done......
Last edited by CuRiOuSfIsH; Nov 15, 2004 at 11:40 PM.
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Originally Posted by lewal
America used the metric system for the same reason we use a different rail system... during WWI or WWII we didn't want to rely on European manufacturers; esp. during time of war.
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Originally Posted by CuRiOuSfIsH
B/c Ronald Ragen said so!
As Sport Compact Car says: torque is for burn outs and drag races, horsepower is for road course races.
As Sport Compact Car says: torque is for burn outs and drag races, horsepower is for road course races.
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Originally Posted by IronFist
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
There's your answer plain and simple
Niether torque or Horsepower is a measure of acceleration.
They are a measure of Moment.
now... back to this Reagan thing
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Rep Power: 340 ok, the Regan thing.... back in the 80's, I think 1983.... Regan was given a choice for America to either go with the British system or the metric system. He said something like "we dont want to be like the rest of the world" so he chose the Brit system for the US.
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Originally Posted by CuRiOuSfIsH
ok, the Regan thing.... back in the 80's, I think 1983.... Regan was given a choice for America to either go with the British system or the metric system. He said something like "we dont want to be like the rest of the world" so he chose the Brit system for the US.
Darn Him ! Darn Him to Heck !
He should of revised the English units making 10 inches equal and foot and ten feet equal a yard, and so on and so on.
Then we coulda had the AMERICAN unit system, which of course the name alone makes it far superior to any other unit systems.
And while we were at it, we could revised the Clock so 20 hours equals a day and 100 minutes equals an hour.
Okay maybe that's going a bit far.
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Rep Power: 382 This is the best explination of Torque Vs Horsepower I could find...
http://vettenet.org/torquehp.html
and to quote it
http://vettenet.org/torquehp.html
and to quote it
The Only Thing You Really Need to Know
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-)
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-)
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Rep Power: 529 ^ I've read that article.
Don't hijack my thread.
So,
You're accelerating faster at 6000rpm because the hp is higher (rpms are higher) even tho the torque is the same?
Don't hijack my thread.
So,
But if torque is what moves you, then your rate of acceleration at those two points should be the same because the torque is the same, right?
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Originally Posted by IronFist
^ I've read that article.
Don't hijack my thread.
So,
You're accelerating faster at 6000rpm because the hp is higher (rpms are higher) even tho the torque is the same?
Don't hijack my thread.
So,
You're accelerating faster at 6000rpm because the hp is higher (rpms are higher) even tho the torque is the same?
The Reagan thing is much more interesting though
NO you can not directly relate ACCELERATION to Torque or to Horse Power, stop trying.
Torque is a measurement of force that pivots around a point.
Otherwise known as a moment
When you turn a doorknob, you are applying a moment.
When you push on the door and the door swings on it's hinge you are appling a moment.
Hp just relates the torque with your engine speed
But it is still the measurement of a FORCE.
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Rep Power: 0 Let me put it in simple terms. You have two trucks towing a boat up to Lake Tahoe on a long grade with the same gearing. One of them has a diesel engine and makes 400 ft-lbs at 2000 rpm, the other is a V10 and makes 400 ft-lbs at 5000 rpm. Guess which one pulls away...
The V10 every time. It's able to do the work at a faster rate.
The V10 every time. It's able to do the work at a faster rate.
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Rep Power: 382 To quote the article HP, once again is just a formula showing you work over time.. (Torque @ RPM)
and once again..."It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.
Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. 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.
and once again..."It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.
Last edited by Zzyzx; Nov 17, 2004 at 10:18 AM.
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Originally Posted by SMX
Let me put it in simple terms. You have two trucks towing a boat up to Lake Tahoe on a long grade with the same gearing. One of them has a diesel engine and makes 400 ft-lbs at 2000 rpm, the other is a V10 and makes 400 ft-lbs at 5000 rpm. Guess which one pulls away...
The V10 every time. It's able to do the work at a faster rate.
The V10 every time. It's able to do the work at a faster rate.
The guy with the bigger shoe size every time!!
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