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Explaining the difference between hp and torque in a simple way can be difficult. There are many practical examples but they don’t provide a full understanding of the essence. I have cut and pasted various explanations with my own edits In an attempt to provide a comprehensive but SIMPLE description of torque and hp. I would be interested in your explanations.
HP VS TORQUE
Torque - how much rotational force can be applied. 1 ft-lb is exactly what it sounds like. You get 1 ft-lb by taking a 1 lb weight and hanging it off a 1 foot stick (ok, a weightless stick). Like a wrench on a nut. The torque is the force to loosen the nut. Power - horsepower is a unit of power... so is ft-lb/sec, which is a bit more descriptive. This is how quickly a force can be applied through movement. The hp is how fast you can turn the nut. If you turn the nut with at least the same amount of force- the faster you turn- the more horsepower you create. That is hp is a function of torque and rpm.
Horsepower, on the other hand, is the rate at which work is done. Torque multiplied by rpm returns horsepower. Basically, the faster the crankshaft spins with at least the same amount of force, the more power an engine will make.
Torque is a measurement of force, hp is the the measurement of work over time
At high RPM, torque drops off primarily from intake and exhaust flow restriction. Volumetric Efficiency declines because the engine can't breathe any faster. Mechanical efficiency also declines at higher RPM, due to increased frictional resistance.
There is no definitive answer as to which is more important torque or hp. A more important consideration is understanding the balance between the two, how they interact or, perhaps, how to influence an engine by giving it more of one or the other. If you want to shred your car tyres, you need some low-down torque, but if you are after land-speed records, then horsepower will always win out.
More torque can pull a bigger boat up a hill- the capacity to do work, pulling the boat up the hill takes work/Torque expresses the turning ability of the engine (the ability to turn its flywheel to accomplish work. The rate of that work is hp. How fast you can pull that boat up the hill is hp.
Another difference between horsepower and torque is that horsepower is energy output over time, and torque is instantaneous. In the context of cars, broadly speaking, this means that a car with a lot of horsepower will have a higher top-speed than the same car with less horsepower. Similarly, a car with a lot of torque will be able to accelerate faster than the same car with less torque, as its instantaneous output will be higher.[e
Horsepower is a unit of power HORSEPOWER = (rpm X torque in ft lbs) / 5200 constant = hp. Power describes how fast energy is exchanged; a use of energy divided by how long it takes to use that energy. Therefore the measurement of horsepower refers to what the sustained output of an engine is.. Power describes how fast energy is exchanged; a use of energy divided by how long it takes to use that energy. Therefore the measurement of horsepowerrefers to what the sustained output of an engine is.
Think of torque as the measurement of strength
Torque expresses the turning ability of the engine (the ability to turn its flywheel) and horsepower meadures the total power output of the engine. In very simple terms, torque is the force you feel pushing you back in your seat on acceleration, while horsepower is the speed achieved at the end of that acceleration.
Torque is a vector quantity. The direction of the torque vector depends on the direction of the force on the axis. Anyone who has ever opened a door has an intuitive understanding of torque. When a person opens a door, they push on the side of the door farthest from the hinges. Pushing on the side closest to the hinges requires considerably more force. Although the work done is the same in both cases (the larger force would be applied over a smaller distance) people generally prefer to apply less force, hence the usual location of the door handle.
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I like to say torque is what gets you going, horsepower keeps you there. If you apply it to a tractor you can pull a house down the street with all the torque it makes, but with 40 hp your top speed is going to be very low.
you can have all the horsepower in the world but if you dont have any torque its going to take a while to get it moving, look at ships and planes.
If you can find a good dyno pull from a regular car vs a good bracket racer you will see 2 distinct humps from the stock vehicle with the horsepower generally lower than the torque, so it will leave a street light pretty good but the top speed is pretty avg. With the bracket racer the torque comes on fast and plateaus then the horsepower meet it and carries the same level for a while. that whole section from the beginning of the first peak past the same level or higher second peak is the power band.
horsepower is a math calculation of the measurement of torque. dynos measure torque and show the calculated horsepower at that point based on RPM.
torque and horsepower are the same at 5250 rpm.
horsepower = RPM X torque / 5250. so torque = horsepower X 5250 / RPM
if my 454 LS5 has a factory published 390 HP peak at 4800 rpm, it should have a torque of ... do the math... 426 at that rpm.
or at the 500 torque peak measured at 3400 will have 323 HP .. at that rpm
your goal to get the highest top speed is to gear your car to hit that speed at the torque peak rpm.
horsepower is torque times rpm. put a torque wrench on a bolt. you are creating 100 ft/lbs of torque. but at 0 rpm. so no hp. at 5454 rpm it is essentially the same number. at least on paper.
no. torque is the ability to move a certain amount of weight. horsepower is the ability to move a certain weight a certain distance in a certain amount of time.
Explaining the difference between hp and torque in a simple way can be difficult. There are many practical examples but they don’t provide a full understanding of the essence. I have cut and pasted various explanations with my own edits In an attempt to provide a comprehensive but SIMPLE description of torque and hp. I would be interested in your explanations.
HP VS TORQUE
Torque - how much rotational force can be applied. 1 ft-lb is exactly what it sounds like. You get 1 ft-lb by taking a 1 lb weight and hanging it off a 1 foot stick (ok, a weightless stick). Like a wrench on a nut. The torque is the force to loosen the nut. Power - horsepower is a unit of power... so is ft-lb/sec, which is a bit more descriptive. This is how quickly a force can be applied through movement. The hp is how fast you can turn the nut. If you turn the nut with at least the same amount of force- the faster you turn- the more horsepower you create. That is hp is a function of torque and rpm.
Horsepower, on the other hand, is the rate at which work is done. Torque multiplied by rpm returns horsepower. Basically, the faster the crankshaft spins with at least the same amount of force, the more power an engine will make.
Torque is a measurement of force, hp is the the measurement of work over time
At high RPM, torque drops off primarily from intake and exhaust flow restriction. Volumetric Efficiency declines because the engine can't breathe any faster. Mechanical efficiency also declines at higher RPM, due to increased frictional resistance.
There is no definitive answer as to which is more important torque or hp. A more important consideration is understanding the balance between the two, how they interact or, perhaps, how to influence an engine by giving it more of one or the other. If you want to shred your car tyres, you need some low-down torque, but if you are after land-speed records, then horsepower will always win out.
More torque can pull a bigger boat up a hill- the capacity to do work, pulling the boat up the hill takes work/Torque expresses the turning ability of the engine (the ability to turn its flywheel to accomplish work. The rate of that work is hp. How fast you can pull that boat up the hill is hp.
Another difference between horsepower and torque is that horsepower is energy output over time, and torque is instantaneous. In the context of cars, broadly speaking, this means that a car with a lot of horsepower will have a higher top-speed than the same car with less horsepower. Similarly, a car with a lot of torque will be able to accelerate faster than the same car with less torque, as its instantaneous output will be higher.[e
Horsepower is a unit of power HORSEPOWER = (rpm X torque in ft lbs) / 5200 constant = hp. Power describes how fast energy is exchanged; a use of energy divided by how long it takes to use that energy. Therefore the measurement of horsepower refers to what the sustained output of an engine is.. Power describes how fast energy is exchanged; a use of energy divided by how long it takes to use that energy. Therefore the measurement of horsepowerrefers to what the sustained output of an engine is.
Think of torque as the measurement of strength
Torque expresses the turning ability of the engine (the ability to turn its flywheel) and horsepower meadures the total power output of the engine. In very simple terms, torque is the force you feel pushing you back in your seat on acceleration, while horsepower is the speed achieved at the end of that acceleration.
Torque is a vector quantity. The direction of the torque vector depends on the direction of the force on the axis. Anyone who has ever opened a door has an intuitive understanding of torque. When a person opens a door, they push on the side of the door farthest from the hinges. Pushing on the side closest to the hinges requires considerably more force. Although the [url=https://www.khanacademy.org/science/physics/work-and-energy/work-and-energy-tutorial/a/what-is-work]work done is the same in both cases (the larger force would be applied over a smaller distance) people generally prefer to apply less force, hence the usual location of the door handle.
I believe every engine regardless of design or size makes the same torque number in ft-lb as horsepower at 5800 rpm. A 1000 cc motorcycle engine might produce 100 horsepower at 13,000 rpm., but put that engine in a 4000 lb pickup truck and it couldn't get out of it's own way since it only produces maybe 20 ft-lb of torque at 1500 rpm. A 3 liter diesel engine might also make 100 horsepower but it makes 200 ft-lb of torque at 1500 rpm and could pull stumps all day. I liked when road testes in magazines showed torque and horsepower vs rpm graphs which give a good indication of how an engine performs.
I like pictures.
302 DZ vs 454 LS5
Only 33 HP apart
but 333 TQ vs 500 (167 apart)
6700 peak HP rpm vs 5200
That describe it?
Stock 302 DZ 357HP @ 6700 333TQ at 4400 The DZ is in Blue, Ford engine is in Red.
LS5 data from GM chart 390 HP @ 4800 500 TQ @ 3200
GM data says LS5 made only 58HP but made 380 TQ at idle! That's more TQ than the DZ ever made!
A 350 LT-1 needs 4000 rpm to make 380 TQ.
Duntov and Pat Bedard tested both the 1970 LT-1 and LS5 at drag strip at almost exactly same times/mph. But noted completely different engine "character".
Last edited by leigh1322; Jun 14, 2021 at 05:14 PM.
Interesting discussion. One of our cars has an interesting hp/torque curve. It's a '20 CT6-V with a 4.2 TT Blackwing V-8 (too bad they built around 350 of them in '19 and another 350 in '20, and then decided to go back to a less expensive alternative. What a great engine, but Cadillac got messed up for a while trying to do the wall street thing). The hp peaks at 550 @ 5700, and the torque at 640 @ 3-4,000. I always figured I like lots of torque at the bottom because, as long as the car has decent traction, you get going real quick. That's one of the reasons I like our '68 L71 - the bb has plenty of grunt down low. But I also enjoy a good sb. Even though technology has come a loooooong way - like getting much more tq/hp out of much lower displacement, better gas mileage, etc. - I still get a bigger smile out of the 'high-strung' performance engines in our vettes.
WOW! this is fascinating. Pardon my simpleton thinking but I do remember from auto shop that one horsepower = 33,000 footpounds/minute. This is really going to light a fire...
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Hp vs torque
