Horsepower and Torque..What??!
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Wow, Im actually kinda suprised at the number of you guys are totally wrong.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
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Actually, the HP is the rate of work...rate meaning there needs to be a time constant.... like a second or minute.
1 hp = 33,000 lb/ft per minute or 550 ld/ft per second. Meaning that a 1 hp rate or work could pull 550 lb at a rate of 1 foot per second.
Now if you increase the amount of torque per the same amout of time unit, the hp goes up and athe velocity goes up...so 2 hp would move 550lbs at a rate of 2 ft/sec.
In an engine you can get more HP 2 ways. You can increase the amount of torque in at a certain rpm* or you and increase the frequency of "torque" happening per time unit (basicly you spin the fucker faster so that there are more combustion strokes ;torque causing moments).
*NOw how can something that has more torque have more hp at the same rpm but go the same speed? You might ask...well it doesn't you still make the same torque and hp if you are going the same rpm, but your throttle plate is closed at that rpm to so you are restricting the hp level by sutting the air flow off (or in the case of deisel you cut the fuel supply). Now If you have more torque, you can increase you speeds and take advantafe of that extra hp. We do this every day when we drive. Byy opeing the throttle more, we create more toqrue...witch makes more HP, and as a result we can cruise at a higher rate of speed by SHIFTING INTO A HIGHER GEAR.
Gears, that bring use to the next part that people are over looking.The 100hp, 100ft/lb car can win or the 200ft/lb can can win. It matters where the PEAK torque is made and what the gearing is.
I car that has a flat, strong torque band and a short rpm range (lets say a redline of 5K). If it makes say the 200 lb/ft of torque but only 100hp (the moath won;t add up, I'm just dumbing it down here)... it can tranfer that torque in to hp by overdriving the input shaft on the transmission.
Now a low torque situation that make peak torque at, lets say, 7K can accel just as fast as the low reving high torque car, but it uses the opposite of over drive to make up for torque...this is a called mechanical advantage. You can diminstrate this by using a simple lever. You have a long handle side and a short 'work' side. You can move the handleside really fast... have high hp, but little torque, but the 'work' side has a high torque number and a lower hp number.
It all comes back to the amount of work per distance... then low torque side moves fast adn covers a long distance, but uses less force, but the high torque side as a low HP and umber because it travel less distance....the RATE has changed.
Now once yo have a certian power lever, you can't really go over that. You put high HP numbers and low torque into one side of the level, you get and equal amount of power out of the other side. But instead you get a high toque and low HP... but its still that same amount of rate of engergy.... Since HP is funtion of torque and a time ( or velocity), the to side equall each other.
Ok , I;m finding it hard to describe the last part, so I will try latter.
1 hp = 33,000 lb/ft per minute or 550 ld/ft per second. Meaning that a 1 hp rate or work could pull 550 lb at a rate of 1 foot per second.
Now if you increase the amount of torque per the same amout of time unit, the hp goes up and athe velocity goes up...so 2 hp would move 550lbs at a rate of 2 ft/sec.
In an engine you can get more HP 2 ways. You can increase the amount of torque in at a certain rpm* or you and increase the frequency of "torque" happening per time unit (basicly you spin the fucker faster so that there are more combustion strokes ;torque causing moments).
*NOw how can something that has more torque have more hp at the same rpm but go the same speed? You might ask...well it doesn't you still make the same torque and hp if you are going the same rpm, but your throttle plate is closed at that rpm to so you are restricting the hp level by sutting the air flow off (or in the case of deisel you cut the fuel supply). Now If you have more torque, you can increase you speeds and take advantafe of that extra hp. We do this every day when we drive. Byy opeing the throttle more, we create more toqrue...witch makes more HP, and as a result we can cruise at a higher rate of speed by SHIFTING INTO A HIGHER GEAR.
Gears, that bring use to the next part that people are over looking.The 100hp, 100ft/lb car can win or the 200ft/lb can can win. It matters where the PEAK torque is made and what the gearing is.
I car that has a flat, strong torque band and a short rpm range (lets say a redline of 5K). If it makes say the 200 lb/ft of torque but only 100hp (the moath won;t add up, I'm just dumbing it down here)... it can tranfer that torque in to hp by overdriving the input shaft on the transmission.
Now a low torque situation that make peak torque at, lets say, 7K can accel just as fast as the low reving high torque car, but it uses the opposite of over drive to make up for torque...this is a called mechanical advantage. You can diminstrate this by using a simple lever. You have a long handle side and a short 'work' side. You can move the handleside really fast... have high hp, but little torque, but the 'work' side has a high torque number and a lower hp number.
It all comes back to the amount of work per distance... then low torque side moves fast adn covers a long distance, but uses less force, but the high torque side as a low HP and umber because it travel less distance....the RATE has changed.
Now once yo have a certian power lever, you can't really go over that. You put high HP numbers and low torque into one side of the level, you get and equal amount of power out of the other side. But instead you get a high toque and low HP... but its still that same amount of rate of engergy.... Since HP is funtion of torque and a time ( or velocity), the to side equall each other.
Ok , I;m finding it hard to describe the last part, so I will try latter.
gadget man
Joined: Aug 2002
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Originally Posted by toast
Wow, Im actually kinda suprised at the number of you guys are totally wrong.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
acceleration by definition: the rate of change of velocity with respect to time; broadly : change of velocity
velocity=what we refer to as speed.
Torque by definition
Function: noun
Etymology: Latin torquEre to twist
1 : a force that produces or tends to produce rotation or torsion <an automobile engine delivers torque to the drive shaft>; also : a measure of the effectiveness of such a force that consists of the product of the force and the perpendicular distance from the line of action of the force to the axis of rotation
2 : a turning or twisting force
what you FEEL is acceleration, which is the rate of change in speed. acceleration is determined, in part by hp but mainly by tq. this is why honda's in general don't get off the line worth a shit ( my car is a honda). weight to hp and weight to tq ratio's play a part in the cars performance but all things being equal tq matters. the car that accelerates faster ( has more tq) gets to top speed faster.
the faster the rate of change in speed the quicker your speedo needle pegs out. if you can get to top speed before your opponent then while your at 125mph your opponent is still at 62.5mph, now stop accelerating and just sustain that speed. your at 125mph and they are at 62.5mph, it's not rocket surgery, who will win?
tq = rotational force, what are your tires doing? rotating. what is your car doing? going in a linear direction (hp). a car with 1000hp and 1lb ft of tq will take so long to get up to speed that you can go to lunch and not miss anything, however when it does get to speed it'll be a few hundred mph.
the opposite is true, a car with 1000lb ft of tq and 1 hp will have a top speed of like .5mph, but it'll get there so quick you blink and you missed it.
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Originally Posted by toast
Wow, Im actually kinda suprised at the number of you guys are totally wrong.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
torque is a force, therefore if there is a force in a certain direction more than in the opposite direction (the force of the pavement pushing against the car), there is not a force equal in both directions, which leads to an acceleration.
if you have 100 more foot lbs of force pushing you in one direction you will accelerate faster than the other car
"g's" is what you feel, 1 g being you body weight pushing against you, 2 g's twice your body weight pushing against you etc. which is the seat of your pants feeling. that is what you feel, caused by the acceleration caused by the torque
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Originally Posted by toast
Wow, Im actually kinda suprised at the number of you guys are totally wrong.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
Torque is what you FEEL. So being in the second car would FEEL like you were accelerating harder, HOWEVER their horsepower is the same. This is what matters, horsepower by definition, is a measure of the cars ability to do work(aka, apply a force) over a distance. They are both applying the same force, and therefore accelerating at the same rate.
Torque, measured alone at the crank, has NOTHING to do with a cars ability to accelerate.
As a few have said already...you dont quite REALLY understand. Go read the link someone posted with the long discussion. Its alllll in there.
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if it's cheap & reliable, it ain't fast, if it's fast & cheap, it ain't reliable, if it's fast & reliable, it ain't cheap
if it's cheap & reliable, it ain't fast, if it's fast & cheap, it ain't reliable, if it's fast & reliable, it ain't cheap
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Originally Posted by toast
Wow, Im actually kinda suprised at the number of you guys are totally wrong.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
To clear things up.
In a race between a car with 100 whp/100ft-lb tq, and a car with 100 whp/200ft-lb tq car...
they would tie.
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No. I understand. You guys need to understand the real physics definitions of force, work, acceleration, and velocity.
"tq = rotational force, what are your tires doing? rotating. what is your car doing? going in a linear direction (hp). a car with 1000hp and 1lb ft of tq will take so long to get up to speed that you can go to lunch and not miss anything, however when it does get to speed it'll be a few hundred mph.
the opposite is true, a car with 1000lb ft of tq and 1 hp will have a top speed of like .5mph, but it'll get there so quick you blink and you missed it."
This is incorrect. Torque means nothing alone. I can twist a wheel in the middle of the road all day long, am I applying a force to it? Yes. Am I doing work on it. NO. Unless you apply a FORCE over a DISTANCE then it doesnt matter if I can apply enough torque to twist a building off its foundation, it still doesnt mean anything.
On top of that you are all leaving out the most important part of the equation, RPM. A car with 100hp and 100ft-lb of torque makes max power at 5252 RPM. A car with 100hp and 200ft-lb of torque makes max power at 2626 RPM. Since the engine has twice the room to rev, it will be able to utilize twice the gearing and they will be both accelerate at the same rate for the same period of time, thus, they will tie.
"tq = rotational force, what are your tires doing? rotating. what is your car doing? going in a linear direction (hp). a car with 1000hp and 1lb ft of tq will take so long to get up to speed that you can go to lunch and not miss anything, however when it does get to speed it'll be a few hundred mph.
the opposite is true, a car with 1000lb ft of tq and 1 hp will have a top speed of like .5mph, but it'll get there so quick you blink and you missed it."
This is incorrect. Torque means nothing alone. I can twist a wheel in the middle of the road all day long, am I applying a force to it? Yes. Am I doing work on it. NO. Unless you apply a FORCE over a DISTANCE then it doesnt matter if I can apply enough torque to twist a building off its foundation, it still doesnt mean anything.
On top of that you are all leaving out the most important part of the equation, RPM. A car with 100hp and 100ft-lb of torque makes max power at 5252 RPM. A car with 100hp and 200ft-lb of torque makes max power at 2626 RPM. Since the engine has twice the room to rev, it will be able to utilize twice the gearing and they will be both accelerate at the same rate for the same period of time, thus, they will tie.
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Originally Posted by toast
No. I understand. You guys need to understand the real physics definitions of force, work, acceleration, and velocity.
On top of that you are all leaving out the most important part of the equation, RPM. A car with 100hp and 100ft-lb of torque makes max power at 5252 RPM. A car with 100hp and 200ft-lb of torque makes max power at 2626 RPM. Since the engine has twice the room to rev, it will be able to utilize twice the gearing and they will be both accelerate at the same rate for the same period of time, thus, they will tie.
On top of that you are all leaving out the most important part of the equation, RPM. A car with 100hp and 100ft-lb of torque makes max power at 5252 RPM. A car with 100hp and 200ft-lb of torque makes max power at 2626 RPM. Since the engine has twice the room to rev, it will be able to utilize twice the gearing and they will be both accelerate at the same rate for the same period of time, thus, they will tie.
your missing some info and have a few things crossed up. Saying that a car with 100 hp and 100 ft lbs makes max power at 5252 isnt right. How in the world can you make that inference? Now if you say the car makes 100 hp AND 100 ft lbs at the exact same time and both are peaks..then yes...it will be at 5252 rpm. Not many cars will make both peak HP AND peak Tq at the cross point of 5252. As a matter of fact I have never seen one. Usually peak Tq is made substantially lower in rpm than peak HP. In other words...just saying the cars HP peaks at 100 and the Tq peaks at 100 is pretty useless to make any prediction on how the car may accelerate. You really need to know what the entire Tq curve (and HP curve) through the RPMs looks like.
Even if we look at yout theoretical engine where we say it makes those peak #s at THE SAME TIME...you still cannot tell which one would be faster. Maybe the one that makes 100ft/lbs at 5252 rpm also makes 95 ft/lbs all the way out to 7500 rpm....and then is geared accordingly. And the other engine drops off drastically just after 2700 rpms. Looking at peak #s alone will never tell you anything. Do yourself a favor and go read the link posted.
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if it's cheap & reliable, it ain't fast, if it's fast & cheap, it ain't reliable, if it's fast & reliable, it ain't cheap
if it's cheap & reliable, it ain't fast, if it's fast & cheap, it ain't reliable, if it's fast & reliable, it ain't cheap
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i can build 2 engines,have the same amount of hp with each,but have the cam profile on one diff so i get more tq.and your going to try and tell me these 2 engines will run the same time as each other in a drag car.
because if u really think that then u my friend are nuts.
because if u really think that then u my friend are nuts.
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