Torque?
12-12-2005, 02:52 PM
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Machine torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,0006,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque at or around zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
[edit]
Relationship between torque and power
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. This means that torque that is causing the angular speed to increase is doing work and the generated power may be calculated as:
Mathematically, the equation may be rearranged to compute torque for a given power output. However in practice there is no direct way to measure power whereas torque and angular speed can be measured directly.
Consistent units must be used. For metric SI units power is watts, torque is newton-metres and angular speed is radians per second (not rpm and not even revolutions per second).
[edit]
Conversion to other units
For different units of power, torque or angular speed, a conversion factor must be inserted into the equation. For example, if the angular speed is measured in revolutions instead of radians, a conversion factor of 2π must be added because there are 2π radians in a revolution:
, where rotational speed is in revolutions per unit time
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbfˇft) for torque and rpm's (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
[edit]
Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by 2π in the above derivation to give:
If torque is in lbfˇft and rotational speed in revolutions per minute, the above equation gives power in ftˇlbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ftˇlbf/min per horsepower:
Because 5252.113... = 33,000 / 2π.
provided by wikipedia ... http://en.wikipedia.org/wiki/Torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,0006,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque at or around zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
[edit]
Relationship between torque and power
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. This means that torque that is causing the angular speed to increase is doing work and the generated power may be calculated as:
Mathematically, the equation may be rearranged to compute torque for a given power output. However in practice there is no direct way to measure power whereas torque and angular speed can be measured directly.
Consistent units must be used. For metric SI units power is watts, torque is newton-metres and angular speed is radians per second (not rpm and not even revolutions per second).
[edit]
Conversion to other units
For different units of power, torque or angular speed, a conversion factor must be inserted into the equation. For example, if the angular speed is measured in revolutions instead of radians, a conversion factor of 2π must be added because there are 2π radians in a revolution:
, where rotational speed is in revolutions per unit time
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbfˇft) for torque and rpm's (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
[edit]
Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by 2π in the above derivation to give:
If torque is in lbfˇft and rotational speed in revolutions per minute, the above equation gives power in ftˇlbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ftˇlbf/min per horsepower:
Because 5252.113... = 33,000 / 2π.
provided by wikipedia ... http://en.wikipedia.org/wiki/Torque
12-12-2005, 02:56 PM
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torque is a circular force. an example of force is when you push a lawnmower. you create a force going in a straight line that pushes the lawnmower. Torque, is just force when you are relating it to a circle. For example, if you take the crankshaft in your motor and turn it, you are creating torque. The reason your wheels spin is because of torque. A force is being exerted on an object to create movement. I hope that made sense. Your best bet would be to just go to google.com and look up torque.
12-12-2005, 10:52 PM
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Originally Posted by OniMirage
Machine torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,0006,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque at or around zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
[edit]
Relationship between torque and power
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. This means that torque that is causing the angular speed to increase is doing work and the generated power may be calculated as:
Mathematically, the equation may be rearranged to compute torque for a given power output. However in practice there is no direct way to measure power whereas torque and angular speed can be measured directly.
Consistent units must be used. For metric SI units power is watts, torque is newton-metres and angular speed is radians per second (not rpm and not even revolutions per second).
[edit]
Conversion to other units
For different units of power, torque or angular speed, a conversion factor must be inserted into the equation. For example, if the angular speed is measured in revolutions instead of radians, a conversion factor of 2π must be added because there are 2π radians in a revolution:
, where rotational speed is in revolutions per unit time
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbfˇft) for torque and rpm's (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
[edit]
Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by 2π in the above derivation to give:
If torque is in lbfˇft and rotational speed in revolutions per minute, the above equation gives power in ftˇlbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ftˇlbf/min per horsepower:
Because 5252.113... = 33,000 / 2π.
provided by wikipedia ... http://en.wikipedia.org/wiki/Torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,0006,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque at or around zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
[edit]
Relationship between torque and power
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. This means that torque that is causing the angular speed to increase is doing work and the generated power may be calculated as:
Mathematically, the equation may be rearranged to compute torque for a given power output. However in practice there is no direct way to measure power whereas torque and angular speed can be measured directly.
Consistent units must be used. For metric SI units power is watts, torque is newton-metres and angular speed is radians per second (not rpm and not even revolutions per second).
[edit]
Conversion to other units
For different units of power, torque or angular speed, a conversion factor must be inserted into the equation. For example, if the angular speed is measured in revolutions instead of radians, a conversion factor of 2π must be added because there are 2π radians in a revolution:
, where rotational speed is in revolutions per unit time
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbfˇft) for torque and rpm's (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
[edit]
Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by 2π in the above derivation to give:
If torque is in lbfˇft and rotational speed in revolutions per minute, the above equation gives power in ftˇlbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ftˇlbf/min per horsepower:
Because 5252.113... = 33,000 / 2π.
provided by wikipedia ... http://en.wikipedia.org/wiki/Torque
Simple answer:
Horsepower is how much power you're making
Torque is what gets you down the track.
Basically, you can make 1000 horsepower all day long, but it doesn't mean squat if you don't have good torque to use that horsepower to get you down the road.
Damn fine detailed explanation though
12-12-2005, 11:00 PM
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Simple Analogy
Overly simple analogy of torque...
Imagine a 1 foot long wrench on say a lug nut. Put 200lbs on the end of that wrench. That lug nut is feeling 200 ft-lbs of torque (same as the advertised crank torque for the SS/SC).
OR
Imagine a 200 foot long wrench on the same lug nut with a 1 lb weight on the end. The result is the same 200 ft-lbs of torque on the nut.
Hope this helps.
Imagine a 1 foot long wrench on say a lug nut. Put 200lbs on the end of that wrench. That lug nut is feeling 200 ft-lbs of torque (same as the advertised crank torque for the SS/SC).
OR
Imagine a 200 foot long wrench on the same lug nut with a 1 lb weight on the end. The result is the same 200 ft-lbs of torque on the nut.
Hope this helps.
12-13-2005, 01:08 AM
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Read this article.... http://vettenet.org/torquehp.html
And then this thread might help a bit more... http://www.*************/forums/showt...1&page=6&pp=10
And then this thread might help a bit more... http://www.*************/forums/showt...1&page=6&pp=10
12-13-2005, 11:18 AM
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Originally Posted by wasey13
Read this article.... http://vettenet.org/torquehp.html
And then this thread might help a bit more... http://www.*************/forums/showt...1&page=6&pp=10
And then this thread might help a bit more... http://www.*************/forums/showt...1&page=6&pp=10
Wow...
That Vette guy could not be MORE WRONG.
Originally Posted by VetteGuy
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.
Otherwise, cars would race in the RPM range with the highest TQ, and not over the RPM range with the highest average HP.
If peak TQ was the best point for racing, then this guy would never want to take his Cobalt SS/SC over 5000rpm, because torque falls off significantly after that point. However, peak HP comes AFTER 5000rpm because the TQ that IS there is being multiplied by the higher RPM's resulting in the range of the highest HP, the actual best rpm range for racing.
Also, if you go by VetteGuy's suggestion that a car pulls harder @ peak tq no matter what the hp is, then that would mean that the Cobalt SS/SC would pull HARDER at 3000rpm than it does at 6000rpm because the tq is much higher, even though the car is making TWICE as much HP @ 6000rpm. Obviously, it is idiotic to suggest that the car pulls harder at 3000rpm than it does at 6000rpm. If you don't realize the stupidity of that suggestion already, go try it for yourself.
The point here is that HP is what really matters.
Based on this equation:
HP ~= (TQ*RPM)/5252
You can see that it takes either TQ OR RPMs to make good hp.
To conclude, I will quote myself from a previous post...
Originally Posted by Blainestang
Torque is greatly misunderstood. Imagine 2 different cars, a Mustang and an S2000, for instance. But for now, lets assume that both have 260hp and weigh the same... basically adding a little weight and power to the S2k. Now, for arguments sake, we'll make some assumptions...
1. Both have LINEAR HP curves, which is not generally the case, but it is a generality
2. The GT makes peak 260hp @4500 rpm and the S2k makes peak 260hp @ 9000 rpm
3. Gearing and Aero is also the same
Now, in this case, because HP is merely a CALCULATION OF TQ and RPM, HP = TQ*RPM/5250 , both cars make the same HP, but the S2k has HALF the tq and TWICE the RPM at that point in order to make the SAME hp.
So, if the cars both weigh the same, have the same aerodynamics, same gearing, and same hp.... DESPITE the GT having TWICE as much TQ, they would be EQUALLY fast if both were at peak hp.
In fact, w/ both curves being linear, the cars would be EQUALLY FAST as long as the S2K kept TWICE the RPMS of the Mustang, and over the powerband that they use, the cars would have the SAME AREA UNDER THE CURVE, which is what really matters.
Essentially, TQ matters only as much as RPM matters. If you gear a car to stay in and use it's high rpm powerband, HP is what is important, not TQ.
Now, a car w/ more tq will be much faster at a given rpm, say @ 2000rpm. An S2000 would barely pull on a civic at that point, but the GT would have pletny of power. So, torquey cars have much more power for just cruising around outside of stratospheric rpms, BUT a car like the RSX-S or S2k can make up for that difference in TQ by using RPMs to multiply it to an equal HP rating.
Hopefully, this made sense. Essentially, HP and powerband (in the case of peaky tq curves and being unable to stay within them) are the most important factors in power output because TQ and RPM can both be made up for w/ more of the other.
1. Both have LINEAR HP curves, which is not generally the case, but it is a generality
2. The GT makes peak 260hp @4500 rpm and the S2k makes peak 260hp @ 9000 rpm
3. Gearing and Aero is also the same
Now, in this case, because HP is merely a CALCULATION OF TQ and RPM, HP = TQ*RPM/5250 , both cars make the same HP, but the S2k has HALF the tq and TWICE the RPM at that point in order to make the SAME hp.
So, if the cars both weigh the same, have the same aerodynamics, same gearing, and same hp.... DESPITE the GT having TWICE as much TQ, they would be EQUALLY fast if both were at peak hp.
In fact, w/ both curves being linear, the cars would be EQUALLY FAST as long as the S2K kept TWICE the RPMS of the Mustang, and over the powerband that they use, the cars would have the SAME AREA UNDER THE CURVE, which is what really matters.
Essentially, TQ matters only as much as RPM matters. If you gear a car to stay in and use it's high rpm powerband, HP is what is important, not TQ.
Now, a car w/ more tq will be much faster at a given rpm, say @ 2000rpm. An S2000 would barely pull on a civic at that point, but the GT would have pletny of power. So, torquey cars have much more power for just cruising around outside of stratospheric rpms, BUT a car like the RSX-S or S2k can make up for that difference in TQ by using RPMs to multiply it to an equal HP rating.
Hopefully, this made sense. Essentially, HP and powerband (in the case of peaky tq curves and being unable to stay within them) are the most important factors in power output because TQ and RPM can both be made up for w/ more of the other.
-Blainestang
12-13-2005, 01:47 PM
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Blaine...reread the article. He says horsepower is what matters. What he means by you will accelerate the hardest , is that you feel torque you don't feel horsepower. Meaning at peak torque you will feel like you are going the fastest, but it doesn't mean you are.
12-13-2005, 03:09 PM
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Originally Posted by wasey13
Blaine...reread the article. He says horsepower is what matters. What he means by you will accelerate the hardest , is that you feel torque you don't feel horsepower. Meaning at peak torque you will feel like you are going the fastest, but it doesn't mean you are.
Basically, this guy just makes it sound like he knows what he's talking about when he really doesn't.
Examples:
Originally Posted by VettGuy
It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*."
Originally Posted by VettGuy
Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve
Originally Posted by VettGuy
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.
Originally Posted by VettGuy
Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context.
For example, I guarantee that an S2000 @ 9000rpm FEELS faster than a Mustang V6 at 2000rpm even though the V6 Mustang is making nearly DOUBLE the torque.
This is kind of a silly example and not exactly parallel because we aren't talking about moments and rotation, but bear with me........ Just imagine that you are standing on a skateboard and someone pushes you from behind with a FORCE of 50 lb. You'll go a little bit and then roll to a stop. Now, imagine that someone pushes you with 50 lb. of force 2000 times per minute. Every time someone pushes you with that force you will accelerate. The force is the same and that's what you're technically "feeling," but you will certainly "feel" like you are accelerating faster also because you are being accelerated 2000 times per minute instead of just once. Now, think about 4000 times per minute. You will accelerate TWICE as fast (eliminating wind resistance and stuff like that) because you are adding that force TWICE as often..... Hopefully that makes sense and the connection between the skateboard and a car can be seen.
Originally Posted by VettGuy
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.
WRONG... WRONG... WRONG.Look at this S2000 Dyno...
The Torque curve is pretty dang flat, so according to this VetteGuy, the S2000 accelerates just as hard at 3000 as it does at 8000rpm.
I mean, would anyone seriously be stupid enough to look at that graph and suggest that?
No, obviously the S2000 is accelerating MUCH harder @ 8000rpm than @ 3000rpm. Why? More HP... and not because of Torque, but because the miniscule torque is being multiplied by 8000rpm.
___________
Need I go on... the guy clearly makes his statements with confidence and makes them sound correct, but they are not. He is wrong on MOST of his points.
12-13-2005, 03:24 PM
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You are taking everything he is saying out of context. You have to read the whole thing.
The curve of the torque curve is determined by RPMs. So you are pushed back in your seat more in a Cobalt SS/SC at peak power then at peak torque? No. You are misunderstanding what he means when he says hard.
We both know that horsepower is more important, no reason to continue this.
The curve of the torque curve is determined by RPMs. So you are pushed back in your seat more in a Cobalt SS/SC at peak power then at peak torque? No. You are misunderstanding what he means when he says hard.
We both know that horsepower is more important, no reason to continue this.
12-13-2005, 03:35 PM
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Originally Posted by wasey13
You are taking everything he is saying out of context. You have to read the whole thing.
The curve of the torque curve is determined by RPMs. So you are pushed back in your seat more in a Cobalt SS/SC at peak power then at peak torque? No. You are misunderstanding what he means when he says hard.
We both know that horsepower is more important, no reason to continue this.
The curve of the torque curve is determined by RPMs. So you are pushed back in your seat more in a Cobalt SS/SC at peak power then at peak torque? No. You are misunderstanding what he means when he says hard.
We both know that horsepower is more important, no reason to continue this.
Yeah, a lot of it is probably semantics...
Either way, like you said, HP is what is ultimately important whether you get it from TORQUE or RPM, both of which don't mean anything without the other.
12-13-2005, 03:38 PM
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Originally Posted by Blainestang
Yeah, a lot of it is probably semantics...
Either way, like you said, HP is what is ultimately important whether you get it from TORQUE or RPM, both of which don't mean anything without the other.
Either way, like you said, HP is what is ultimately important whether you get it from TORQUE or RPM, both of which don't mean anything without the other.
12-13-2005, 07:18 PM
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Originally Posted by R33P3R007
you guys just confuse me
In simple terms, without getting technical, torque is the low end grunt of an engine, HP is the top end power.
So when you punch the gas at a low RPM in a V8 car and it pushes you back into the seat and pulls hard - thats torque.
When you're driving a Honda S2000 and you punch it at a low RPM, nothing happens. The engine bogs and starts to slowly accelerate. Once you get into the powerband though, usually around 6,000RPM, it starts to pull hard - thats Horsepower.
Both HP and Torque coexist throughout the rev range of an engine, but in general torque is more important in the low RPM's while HP is more important in the higher RPM's. Torque is a measurement of the power of an engine, while Horsepower is a measurement of how much work that torque can do at any given RPM.
Hope that helps.
12-13-2005, 08:48 PM
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Originally Posted by wesmanw02
Maybe this will help you understand the concept a little better:
In simple terms, without getting technical, torque is the low end grunt of an engine, HP is the top end power.
So when you punch the gas at a low RPM in a V8 car and it pushes you back into the seat and pulls hard - thats torque.
When you're driving a Honda S2000 and you punch it at a low RPM, nothing happens. The engine bogs and starts to slowly accelerate. Once you get into the powerband though, usually around 6,000RPM, it starts to pull hard - thats Horsepower.
Both HP and Torque coexist throughout the rev range of an engine, but in general torque is more important in the low RPM's while HP is more important in the higher RPM's. Torque is a measurement of the power of an engine, while Horsepower is a measurement of how much work that torque can do at any given RPM.
Hope that helps.
In simple terms, without getting technical, torque is the low end grunt of an engine, HP is the top end power.
So when you punch the gas at a low RPM in a V8 car and it pushes you back into the seat and pulls hard - thats torque.
When you're driving a Honda S2000 and you punch it at a low RPM, nothing happens. The engine bogs and starts to slowly accelerate. Once you get into the powerband though, usually around 6,000RPM, it starts to pull hard - thats Horsepower.
Both HP and Torque coexist throughout the rev range of an engine, but in general torque is more important in the low RPM's while HP is more important in the higher RPM's. Torque is a measurement of the power of an engine, while Horsepower is a measurement of how much work that torque can do at any given RPM.
Hope that helps.
12-13-2005, 09:24 PM
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I will give it a shot for you, remember this is extremely simplified;
Power = torque times velocity. The formula is not that complex, but to make it easier, it simplifes to: Horsepower=torque times RPM divided by 5252 once the constants are multiplied out.
So you have HP = torque*RPM/5252
So if your car makes 200 ft*lbs of torque at 2000 RPM, you get Power (aka horsepower) = 200*2000/5252 or 76 HP. This is the force that accelerates your vehicle (ignoring all drivetrain losses/wind resistance/etc.)
Now, lets say that you are running at 5500 RPM where the car is making 150 ft*lbs of torque. The power available to accelerate your vehicle is 150*5500/5252 or 157 horsepower. Again ignoring all the factors that bleed off net power available to accelerate the car, you are obviously going to accerate faster with just over twice as much power being generated.
The formula is why all internal combustion engines have the torque curve intersect the horsepower curve at 5252 RPM. Go ahead and plug in any torque number in the formula, use that 5252 RPM and see what you get for horsepower.
Power = torque times velocity. The formula is not that complex, but to make it easier, it simplifes to: Horsepower=torque times RPM divided by 5252 once the constants are multiplied out.
So you have HP = torque*RPM/5252
So if your car makes 200 ft*lbs of torque at 2000 RPM, you get Power (aka horsepower) = 200*2000/5252 or 76 HP. This is the force that accelerates your vehicle (ignoring all drivetrain losses/wind resistance/etc.)
Now, lets say that you are running at 5500 RPM where the car is making 150 ft*lbs of torque. The power available to accelerate your vehicle is 150*5500/5252 or 157 horsepower. Again ignoring all the factors that bleed off net power available to accelerate the car, you are obviously going to accerate faster with just over twice as much power being generated.
The formula is why all internal combustion engines have the torque curve intersect the horsepower curve at 5252 RPM. Go ahead and plug in any torque number in the formula, use that 5252 RPM and see what you get for horsepower.
12-13-2005, 10:48 PM
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Originally Posted by wasey13
No... have you not read anything we have been saying?
Like I said, it wasn't in technical terms, just plain English.
12-13-2005, 10:59 PM
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Originally Posted by wesmanw02
Please tell me how thats wrong.
Like I said, it wasn't in technical terms, just plain English.
Like I said, it wasn't in technical terms, just plain English.
12-13-2005, 11:11 PM
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Originally Posted by Blainestang
Look at this S2000 Dyno...
The Torque curve is pretty dang flat, so according to this VetteGuy, the S2000 accelerates just as hard at 3000 as it does at 8000rpm.
I mean, would anyone seriously be stupid enough to look at that graph and suggest that?
No, obviously the S2000 is accelerating MUCH harder @ 8000rpm than @ 3000rpm. Why? More HP... and not because of Torque, but because the miniscule torque is being multiplied by 8000rpm
Need I go on... the guy clearly makes his statements with confidence and makes them sound correct, but they are not. He is wrong on MOST of his points.
The Torque curve is pretty dang flat, so according to this VetteGuy, the S2000 accelerates just as hard at 3000 as it does at 8000rpm.
I mean, would anyone seriously be stupid enough to look at that graph and suggest that?
No, obviously the S2000 is accelerating MUCH harder @ 8000rpm than @ 3000rpm. Why? More HP... and not because of Torque, but because the miniscule torque is being multiplied by 8000rpm
Need I go on... the guy clearly makes his statements with confidence and makes them sound correct, but they are not. He is wrong on MOST of his points.
My previous post showed why the vehicle will change its rate of speed more as power increases regardless of the torque made.
The slope of the horsepower curve will increase as the peak torque increases, decrease when the torque curve decreases and show a maximum slope at the torque peak. It is hard to see on this dyno, but if you see where the torque peak is, you will notice that the slope of the horsepower curve is at its maximum. As the torque drops off, the power increases because of the velocity increase more than offsets the lower torque, but the rate of change is less. Boils down to this: at the torque peak, the acceleration is at maximum, for every extra RPM there will be the greatest change in horsepower. That means that on a motor that peaks torque at 3500 RPM might show an increase of 35 horsepower from 3000-3500 RPM and another 35 horsepower from 3500-4000 RPM. That same engine might show a gain of 28 horsepower from 4000-4500 RPM and a gain of 24 horsepower from 4500-5000 RPM. The car will go faster with the higher horsepower as that is a measurement of the force (ignoring mass, as it is the same car), but the rate of the change follows the torque curve.
Now go back and substitute the word 'acceleration' for the phrase 'rate of change' as that is the definition of acceleration.
The greatest acceleration is experienced at the torque peak. Imagine a tach that goes to, say 10,000 RPM. On the CSS you jump on the gas in neutral. The tach moves up toward the torque peak, it starts off (relatively) slowly and moves faster as it climbs up towards the torque peak. At that peak, the needle is accerating as fast as it ever will. Once past the torque peak, it will still climb, but the needle is now moving slower. It is accerating more slowly. When the CSS runs out of boost and cam/heads the torque takes a huge nosedive. The horsepower is still there, the car has a lot of power to change its rate of speed, but the tach needle now starts to crawl upward, much more slowly accelerating than at the torque peak. You are now at 7000 RPM, ignoring PCM restraints/valve spring limits and such, your car is making pathetically low torque and the horsepower curve is starting to drop off. It is still making more power than it was at torque peak, but the acceleration is almost nonexistant.
Hope that clears up the confusion over the term acceleration. A very common miscommunication between folks.