horsepower:torque relationship?
On The Tree
Joined: Nov 2006
Posts: 111
Likes: 0
James Watt, the man that first dubbed the term horsepower. He wanted to see how much coal the average horse could move per unit time. Just think if he would of used a donkey, we would all have 325 a.p. cars (asspower) 
Teching In
Joined: Jun 2010
Posts: 14
Likes: 0
I am satisfied with all answers in this thread. It has my blessing.
8 Second Club
Joined: Aug 2007
Posts: 160
Likes: 0
From: Statham,Ga
I like to think of TORQUE as how big a hammer you pick for the job,...
the number of times you strike the nail is RPM.....
AND, the time it takes to drive a nail is HORSEPOWER.
Therefore you can select a big hammer and drive the nail with 3 swings......OR
you could pick a small hammer and drive the nail with 20 quick swings.
IF the time to drive the nail is the same for each example,....the horsepower is the same.
This is how a small import turning 10,000 rpm can match HP with a big inch motor
turning 6500 rpm.
Crude example but true.
the number of times you strike the nail is RPM.....
AND, the time it takes to drive a nail is HORSEPOWER.
Therefore you can select a big hammer and drive the nail with 3 swings......OR
you could pick a small hammer and drive the nail with 20 quick swings.
IF the time to drive the nail is the same for each example,....the horsepower is the same.
This is how a small import turning 10,000 rpm can match HP with a big inch motor
turning 6500 rpm.
Crude example but true.
Last edited by magnum-gto; Jul 22, 2010 at 09:02 AM.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
Good example. For those still confused, just think that torque is a force
but Horsepower is just a measurement...a measurement of force over time.
I'm under the impression some people confuse horsepower as a force when
they say, "I'd rather have more horsepower than torque at xxx RPM."
but Horsepower is just a measurement...a measurement of force over time.
I'm under the impression some people confuse horsepower as a force when
they say, "I'd rather have more horsepower than torque at xxx RPM."
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Also note that F = m.a, so P = m.a.v (i.e. instantaneous RWHP can be calculated from logging v while driving).
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
if you push on a wall, you are doing work on the wall. just because the wall isint moving, doesnt mean your not doing work.
remember Newton's Law. (one of them) For every action there is an equal but opposite reaction.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
Grab the Horsepower formula and view the result if the distance (RPM) is zero.
Calculating Work:
Work is applying a force over a distance. Force is any cause that changes the position, motion, direction, or shape of an object. Work is done when a force overcomes a resistance. Resistance is any force that tends to hinder the movement of an object.If an applied force does not cause motion the no work is produced.
To calculate the amount of work produced, apply this formula:
W = F x D
Work is applying a force over a distance. Force is any cause that changes the position, motion, direction, or shape of an object. Work is done when a force overcomes a resistance. Resistance is any force that tends to hinder the movement of an object.If an applied force does not cause motion the no work is produced.
To calculate the amount of work produced, apply this formula:
W = F x D
W = 0
HP = rpm x T
_________
5252
_________
5252
HP = 0 / 5252
HP = 0
FNG again. drumming up old *** posts. (for the other FNG's?)
A nameless quote, "There are engines that have lots of horsepower and torque. They are called race cars. There are engines that have lots of torque and some horsepower. They are called dumptrucks."
I'm sure this won't make me lots of friends here, but hopefully it gets some gears turning.
it's been said so many times here. But one more time. And hopefully I might say it in a way that lets some that haven't got it yet... get it. As basic as I had to put it in my own head to fully understand it. Horsepower is how fast a motor puts out torque. The more horsepower you have compared to a static torque number, the faster it is.
I had to break that simple thing up into 4 simpler versions. hopefully it helps others too.
Four different ways of viewing what kind of motor you want.
1 You can quickly put out lots of torque
2 or quickly put out a little torque
3 You can slowly put out a Lot of torque
4 or slowly put out a little torque.
Honestly the last two didn't sound very appealing. But factually the middle two are very much the same. If geared right as pointed out by many examples here. (taking revs into account but using that makes it confusing again) There are of course infinite variations but these are the most extreme to make the point.
I personally would be happy with a lot of HP and a medium amount of torque that revs high. (gearing makes up for torque - I road race.) But if I can have the best of everything, lots of hp and torque would be best. And so would being a rock star. Rich AND famous. It happens, but not often.
A nameless quote, "There are engines that have lots of horsepower and torque. They are called race cars. There are engines that have lots of torque and some horsepower. They are called dumptrucks."
I'm sure this won't make me lots of friends here, but hopefully it gets some gears turning.
it's been said so many times here. But one more time. And hopefully I might say it in a way that lets some that haven't got it yet... get it. As basic as I had to put it in my own head to fully understand it. Horsepower is how fast a motor puts out torque. The more horsepower you have compared to a static torque number, the faster it is.
I had to break that simple thing up into 4 simpler versions. hopefully it helps others too.
Four different ways of viewing what kind of motor you want.
1 You can quickly put out lots of torque
2 or quickly put out a little torque
3 You can slowly put out a Lot of torque
4 or slowly put out a little torque.
Honestly the last two didn't sound very appealing. But factually the middle two are very much the same. If geared right as pointed out by many examples here. (taking revs into account but using that makes it confusing again) There are of course infinite variations but these are the most extreme to make the point.
I personally would be happy with a lot of HP and a medium amount of torque that revs high. (gearing makes up for torque - I road race.) But if I can have the best of everything, lots of hp and torque would be best. And so would being a rock star. Rich AND famous. It happens, but not often.
Teching In
Joined: Jun 2011
Posts: 27
Likes: 0
From: Long Island, NY
I read somewhere and it it my understanding that HP is a measure of the rate of acceleration of the engine. This is why horsepower increases as rpm increases as long as there is sufficient torque to resist the drag and imperfections in the engine. An engine at WOT is creating a chain reaction only interrupted by the rev limit or resistance/drag. The rate at which the reaction occurs exponentially increases as rpm increases until the engine cannot tolerate the forces applied.
Example: an aggressive cam coupled with forged parts for durability may produce more torque at a higher rpm therefore counter-acting the increased drag (both mechanical and environmental) at X rpm and allowing the engine to reach higher horsepower.
Example: an aggressive cam coupled with forged parts for durability may produce more torque at a higher rpm therefore counter-acting the increased drag (both mechanical and environmental) at X rpm and allowing the engine to reach higher horsepower.
