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Quote:

Originally Posted by Bang&Olufsen DK

you divide 100lbs by 500lbs/ft and get 5ft. for every 1 ft there was 100lbs of force applied. thereby, the resulant functioning force of the rod for torque multiplication would be 100 pound per foot, OR 100lbs/ft.

no disrespect or anything, but your units are reversed. Torque is a force multiplied by a distance, not divided by a distance. This is the essense of your example. 100 lbs of force, multiplied by a 5 ft lever gives you 500 lbs*ft of torque. It is because they multiply that levers give you MORE torque instead of less.

If it was divided then your lever would make it harder to turn a bolt instead of easier. Also, just examining the units by themselves, if you had 500 lbs/ft of something and divided it by 100 lbs, you would get 5/ft which is not the same as 5 ft. If you divide the 100 lbs by 500 lbs/ft you will get 1 ft / 5, which is clearly not what you are looking for. The units are just reversed, that's the only thing I see wrong.

Anyway, that was a great writeup on horsepower, I very much enjoyed reading what it means in relation to work, rpm, and time.

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Quote:

Originally Posted by kotetu

no disrespect or anything, but your units are reversed. Torque is a force multiplied by a distance, not divided by a distance. This is the essense of your example. 100 lbs of force, multiplied by a 5 ft lever gives you 500 lbs*ft of torque. It is because they multiply that levers give you MORE torque instead of less.

If it was divided then your lever would make it harder to turn a bolt instead of easier. Also, just examining the units by themselves, if you had 500 lbs/ft of something and divided it by 100 lbs, you would get 5/ft which is not the same as 5 ft. If you divide the 100 lbs by 500 lbs/ft you will get 1 ft / 5, which is clearly not what you are looking for. The units are just reversed, that's the only thing I see wrong.

Anyway, that was a great writeup on horsepower, I very much enjoyed reading what it means in relation to work, rpm, and time.

which was exactly my point for the past page, i just didnt know how to word it. thank you, kotetu.

i never meant any disrespect bang, it was a good write-up, but i just couldnt make you see that it IS ftlbs because its ft*lbs and not because it is lbs/ft and its easier to say ftlbs...

Actually Kotetu it can be said both ways but they arrive at a similar conclusion, just looked at in a different way.

I'll admit there was some confusion in this thread and people misunderstood each other but they do break down to roughly the same thing, just looking from a different perspective.

Bang was right it was changed by us in the automotive industry. Just think of it this way: When you are talking about the specification of a force that must be applied to a specific bolt, it is the opposite of the way of finding out how much force an engine applies to the flywheel.

I'll go into further detail if you'd like, but I'm bout to hit the sack. Pretty much everyone in this thread is right, but no one is really wrong. That's why the debate started in the first place is because it was mentioned that Bangs info wasn't actually correct (don't worry Ikeray, not saying anything bad just explaining the situation) which it actually was in the context of which he was speaking.

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the tundra commercial pisses me off! its towing 8500 lbs (or so they say) and ask, "what does it take to earn the award for best towing?" or something like that, "raw horsepower".....wait, isnt it torque that lets you go from 0-60 the fastest when towing, not hp?

the tundra commercial pisses me off! its towing 8500 lbs (or so they say) and ask, "what does it take to earn the award for best towing?" or something like that, "raw horsepower".....wait, isnt it torque that lets you go from 0-60 the fastest when towing, not hp?

lol i noticed that too, but i guess most people who dont know about HP and TQ dont know the difference, and they are more familiar with HP so thats what they market. But that new Tundra is a beast, im a big fan of Toyota trucks, they are very well made.

and i was quoting straight from wikipedia about the lb*g*ft/sec.

kg is a mass, lbs is a weight (being in constant acceleration you get weight from a mass). now whos the dumb one, the formula is always kg*g(gravitational force)*ft/sec, i just defined gravity as 9.8 in which you can formulate lbs from grams because we have the simple conversion for this. yes, i shouldve excluded gravity from the lb*ft/sec, but even still, it is STILL ft.lbs/sec, not lbs/ft. we would call it lbs/ft if thats what it really was, thats why we call it miles PER hour and not miles-hours, SEE HOW THAT WORKS!?!?!?!

Huh, how stupid is this..... I know this post is very old, but I couldn't help it.
Kg is a weight and lbs is a weight, they are just different. Kg being the european version and lbs being the american.

Accelaration is about both HP and torque not just torque.
To put it out here very simple or in black in white, the easiest explanation would be that Horsepower is the power that makes you go fast, so 230hp will make you go a lot faster than 200hp and torque is how fast you use those horsepowers.
But that doesn't mean that a car with lets say 200HP and 210lbs-ft.(torque) will be faster than a car with 230HP and 206lbs-ft.(torque), just because the torque rating is slightly higher, it's actually the other way round.
The HP is the potential max power of the car, so if you reach max HP (230hp) at 6200rpm and 206lbs-ft at 5000rpm instead of 200HP at 5500rpm and 210lbs-ft. at 4500rpm, then yes the car with only 206lbs-ft, of torque will be the quickest. It can never be the other way around.

Maybe it's a bit confusing, but HP is the max speed available and the torque is how fast you use that speed.
So if your car has a top speed of 155mph because of 230hp compared to a top speed of 140mph because of 200 hp, then your car(the first) has more power to use and the torque will use that power with a specific efficiency (torque).
So having a huge amount of torque doesn't give you much without the HP.
It's like big tractor, bulldozer or truck.... They have a lot of torque but not that much HP, because they need to be able to pull heavy stuff off the line(from stop), so they need a lot of torque, but they never get to a high speed because they miss high HP rating.

Ah..... this is hard to explain..... damn it.
Torque is the force in weight the car can pull, so a higher number makes the car pull harder, but without power those torque are worth nothing.
Dragsters are perhaps the fastest and quickest road vehicles we know and they have a gigantic amount of HP and Torque, meaning they have both in levels out of this world. F1 racers have a lot of HP and very little torque and still these cars are fast but in another way than dragsters. Tractors, buldozers, trucks etc. have higher torque ratings and less HP, and they are really slow, though they will go from stop to highest speed in no time, when also thinking about it's total weight.
So you see my point.

So all the talk about HP vs. Torque is just silly, because it's a combination of both that makes your car fast when accelarating.

easy there sparky, that conversation ended a while ago

Horsepower and Torque were thoroughly explained in the first post

and just for clarification...torque is your motivation. Nothing more Nothing less...Your car moves at EVERY speed because of your torque...

Horsepower, Pferdestarke, Kilowatts, MonkeyPower...they're all a function of your torque flattened out over a distance.........as i explained in the first post.

hahaha what a bump to start an argument to a conversation that happened like 1 year ago this is a good bump tho it straightened me out when i first saw this sight...

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I haven't read through this thread, but Gothche seems either terribly confused or really bad at explaining things.

The only really great explanation of HP and torque I've ever found is this page

Quote:

Originally Posted by Gothche

Huh, how stupid is this..... I know this post is very old, but I couldn't help it.
Kg is a weight and lbs is a weight, they are just different. Kg being the european version and lbs being the american.

Generally speaking, kilograms are a measure of mass and pounds are a measure of force (weight is a force). It just so happens that over the surface of the earth there's a fairly constant proportion between weight and mass (it's called gravity) so we tend to interchange them. Technically if I step on a bathroom scale I'm measuring my weight (force) directly, and if I step on a balance scale I'm measuring my mass directly.

It's common to see imperial mass measured in "pounds mass", with 1 lbm. equal to the mass that weighs 1 lbf (pound force, at sea level IIRC). Conversely there is a kilogram of force, which is the weight of 1 kg.. The only time a pound and a kilogram are measures of the same property is if you're comparing lbf to kgf, or kg to lbm. It'd be very helpful if lbf. and lbm. were specified when talking about "pounds".

The pounds portion of torque is lbf.

Quote:

Accelaration is about both HP and torque not just torque.
To put it out here very simple or in black in white, the easiest explanation would be that Horsepower is the power that makes you go fast, so 230hp will make you go a lot faster than 200hp and torque is how fast you use those horsepowers.

Horsepower is simply a combination measure of how fast the engine is turning and how much torque it's making. 200 ft.lbs at 6000 RPM is more power than 200 ft.lbs at 5000RPM. That's all there is to it. In speed applications torque at higher RPM is more valuable than torque at lower RPM because you can gear down the higher RPMs to get more force to the ground, and this is why people compare HP.

Quote:

But that doesn't mean that a car with lets say 200HP and 210lbs-ft.(torque) will be faster than a car with 230HP and 206lbs-ft.(torque), just because the torque rating is slightly higher, it's actually the other way round.
The HP is the potential max power of the car, so if you reach max HP (230hp) at 6200rpm and 206lbs-ft at 5000rpm instead of 200HP at 5500rpm and 210lbs-ft. at 4500rpm, then yes the car with only 206lbs-ft, of torque will be the quickest. It can never be the other way around.

What are your definition of "faster" and "quickest". If "faster" is in terms of max speed, see below.

If we're talking about acceleration it's much more complex. The entire torque vs. RPM curve comes into play, but generally speaking you'll be putting more force on the ground if you can keep producing torque up to a higher RPM (which means higher HP).

Quote:

Maybe it's a bit confusing, but HP is the max speed available and the torque is how fast you use that speed.

No, no, no, no, no.

The maximum speed is determined by how fast you can get the engine to rev and the gearing. If you have two cars that both rev to 6000 with identical gearing (and can get to redline in the highest gear) they'll have exactly the same top speed, even if one has more horsepower. Higher horsepower engines are usually higher revving, so picking it to have a better top speed is reasonable, but HP is not the max speed available.

Quote:

So if your car has a top speed of 155mph because of 230hp compared to a top speed of 140mph because of 200 hp, then your car(the first) has more power to use and the torque will use that power with a specific efficiency (torque).

Torque has nothing to do with how efficiently you're using power. Nothing.

Quote:

So having a huge amount of torque doesn't give you much without the HP.
It's like big tractor, bulldozer or truck.... They have a lot of torque but not that much HP, because they need to be able to pull heavy stuff off the line(from stop), so they need a lot of torque, but they never get to a high speed because they miss high HP rating.

This is true, but poorly put. They need to produce lots of torque at low RPM. The tradeoff to this is their ability to rev up, which simultaneously limits their top speed and power. Being able to run an engine at high RPM is good for both torque and top speed. They don't miss out on top speed because of low HP, they miss out on both HP and top speed because they don't rev well.

It's hard to explain because there aren't as many absolutes as people would like to believe. Making a pile of torque is useless if you can't rev your engine up to speed, making a pile of horsepower is useless if your low rpm torque isn't enough to get the car moving, but in reality every car is somewhere in between.

Quote:

Torque is the force in weight the car can pull, so a higher number makes the car pull harder, but without power those torque are worth nothing.
Dragsters are perhaps the fastest and quickest road vehicles we know and they have a gigantic amount of HP and Torque, meaning they have both in levels out of this world. F1 racers have a lot of HP and very little torque and still these cars are fast but in another way than dragsters. Tractors, buldozers, trucks etc. have higher torque ratings and less HP, and they are really slow, though they will go from stop to highest speed in no time, when also thinking about it's total weight.
So you see my point.

Just out of curiosity, what "another way" of fast is the difference between F1 and drag cars? I honestly don't know how much torque an F1 car produces, but putting a lot of force on the road is the goal in every type of racing.

Quote:

So all the talk about HP vs. Torque is just silly, because it's a combination of both that makes your car fast when accelarating.

How much horsepower you've got is a direct function of how much torque you can make and how high you can make it in the RPM band. If you increase torque across the band you're improving your horsepower as well.

Talk of HP vs. Torque isn't really silly, because there are very practical differences in driving depending on if you make your torque at high RPM or low RPM, and this is what people are really talking about in HP vs. Torque.

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Just a bit of friendly nitpicking on a good sticky Some of my points are admittedly pedantic. I won't claim to have perfect knowledge on this, so any discussion and/or disagreements are welcome.

Quote:

Originally Posted by B+O

Torque, as by its definition, is a twisting force. As by its unit of measurement, it's pretty dern straight forward. Nm (Newtons per meter), Kgm (Kilograms per Meter), Lbs.ft (Pounds per foot, or as we car people changed it to "Foot-Pounds") and any other mixture of unit measurement and unit force.

The units are actually Newton meters, kilogram force meters, and pound feet. It's a product of how much force you apply and how far away it's being applied. I'd also suggest specifying kilograms force (kgf) meter instead of kilogram meter, since a kilogram is usually unambiguously a mass.

Edit: I see this has been discussed before ... but reading through I can't even tell who was arguing what The torque produced is a product of a distance and a force, not a ratio. Because of this there should be no "per" in the unit name and the order of the distance and force units is not significant (though they could be strongly ingrained, I know I would never say "meter Newtons"). This is consistent with 5ft x 100 lbs = 500 ft. lbs.

Quote:

Horsepower is something that people really dont understand too much. Without going into too much about kinetic physics and stuff, it's pretty much energy capable of being done in an amount of time, just like a Watt (or similarly a Joule with direction). Ever wonder why there's so many ways to calculate the rated power of an engine? you've got horsepower (hp) Pferdestarke (PS), Kilowatt(kW) and some others im missing. The one that should really make you question hp is kW.

A Joule, besides being a scalar quantity and not having direction, isn't a unit of power.

Quote:

What is a Kilowatt? well from the top, a Kilowatt is the amount of energy that can be produced over a certain amount of time with a direction, and this is equal to "work" or action taken on an object. If no motion is made, no work is done. i believe the time is 1 second. energy is a function of Force and distance in relation to time. To get more work done in a set time frame, you need to have more speed, or cover more ground. however you cover more ground is irrelevant at the current time. just know that to cover more ground in the same amount of time. you've had to expend more energy. in order to move 738 lbs 1 foot in one second, you basically need act 1 kilowatt of energy on that object.

I think this would be more clear if you just stuck to defining power as an amount of work done per unit time, leaving energy out of it. Purely opinion, of course. Also, as noted above for Joule, neither energy nor work have direction.

Quote:

now horsepower says that you have the ability to move five-hundred fifty pounds (550lbs) 1 foot, in one second.

In this sample, and the one in the previous paragraph, it should be "the ability to lift at constant speed" as opposed to "the ability to move" since the force applied is what's used in calculating work. By lifting 550 lbs without accelerating it you're actually applying 550 lbs. of force, which isn't the case for pushing a 550 lb. block.

Quote:

Now putting it in terms of engines and power, imagine a crankshaft. you can see it spinning? take the stroke of our C32A engine at 84mm...multiply that by pi, then by rpm, divided by 1000, and then divide that by 60 and that will give you a number i dont know what to do with (j/k) but right now im just showing you what we did

For the calculations that you do (that I cut out) it might be good to carry some decimal places, since you should exactly double the resulting speed and distance for a doubled engine speed.

Quote:

energy in a direction over a set amount of time is equal to 1 watt. 745 watts equal 1 hp.

No direction. Work done or energy produced/transferred over a set time gives power.

Quote:

this is how engine dynos work. it gives a certain amount of resistance, the force needed to overcome that resistance is measured, if the force stays the same as the distance per second increases, the work done increases or...HP increases.

if you examine these, you'll find that as rpm, or distance covered in a set amount of time (think about the circumfrencial stroke of the crank shaft as a linear motion as opposed to eccentric or circular) get's greater. as does the work produced as well.

I think "the work done per second increases" would be more clear (emphasizing that power is the rate of doing work).

Quote:

in the second one you can see that the graph is still going up even up to its revlimit. that is...the HP is still climbing as well as the torque. But if you look closer, you'll see that HP is climbing at an exponential rate compared to torque. if the engine were to keep a constant torque (force) from 5000 through to 10,000 rpm the hp would be double that at 5000rpm, simply because the linear distance of the crankshaft doubled and inherently producing more work...

It's not rising at an exponential rate, just rising as a function of both torque and RPM.

Quote:

125lbft of torque at 20,000rpm will give you 480hp. this is how F1 engines produce such ridiculous amounts of "WORK DONE" that can continue to accelerate long after a car of the same amount of power would have had to shift. there for more work is done and less time is wasted. I.E. turns into faster times.

I think this is missing a key opportunity to introduce gearing, and being able to put more torque to the axles than you have at the flywheel. It's not only saving shift times that makes high revving engines fast.

Quote:

lets break a formula engine down to it's numbers...i believe it was a BMW engine that produced 950hp but that's all that was advertised. why? to make people think it was an amazing thing. what's really at work here is the power done. if we were to take it's numbers and find out the torque it produces at its rated peak HP rpm we'd stumble onto this...

at 19,000rpm (which is the advertised peak HP rpm) the BMW made 950hp...throw it through the math of 950x5252(a constant used in this calculation)/19000 we get

262.6lbft

do what? that's exactly right. 262lbft of torque...not much oomph is it? not compared to its hp, but in a light chassis like an F1 you get supremely fast acceleration because such a light chassis would accelerate like that with that amount of force.

Gearing comes into play here as well. If you gear that 19000 RPM down to 9500 RPM you're now getting 525 ft.lbs of torque ...

Quote:

since the car is light...you just played with the first equation too. F=ma...or F/m=a.

Maybe a note that torque at the wheels is related to force on the road by the wheel radius?

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