HP/torque
- Thread starter havoc
- Start date
The standard formula to calculate horsepower - at least the formula I've always known and used - is torque times rpm divided by 5252.
This would mean that multiplying the torque figure by 5252 and then dividing it by 5252 to arrive at a horsepower figure would result in the torque figure we started with - the multiplication and division canceling eachother out.
Steve
YOU back there in the back - yeah you -- you just earned yourself detention little mister. Another word and it's straight to the Principal's office...ahh i forgot my calculater oh and my pocket protector
Steve
Mikey D
Registered
Ummm
NO!
Horse power and torque have little or nothing to do with each other.
Mr. D steps up to the podium:
Horse power is the total amount of energy converted to work by the bike. Horse power is seeing the needle swing as far to the right as possible. Horse power will give you the top speed.
Torque is the twisting force. Torque is how hard the bike can accelerate. Torque is the push you back feeling you get when you twist the throttle.
Any questions?
Mr. D steps down.
NO!
Horse power and torque have little or nothing to do with each other.
Mr. D steps up to the podium:
Horse power is the total amount of energy converted to work by the bike. Horse power is seeing the needle swing as far to the right as possible. Horse power will give you the top speed.
Torque is the twisting force. Torque is how hard the bike can accelerate. Torque is the push you back feeling you get when you twist the throttle.
Any questions?
Mr. D steps down.
Mikey D
Registered
Torque is usually (in America) measured in foot pounds. the easiest way to picture it is to picture a wrench that is 1 foot long held horizontally on a bolt. If you put a 10 pound weight on the end of the wrench you have generated 10 ft/lbs of torque.
Horse power is derrived from the average strength of a draft horse. It was found tha the average draft hourse could lift 330 lbs, 100 feet in one minute. (I think I have my #'s correct) Picture a horse tied to a rope that is thrown over a pully, hanging off a cliff. Hang a 330 lb weight from the rope and smack the horse on the azz. The horse could pull the 330 lb weight up 100 feet in one minute. This equals one horse power.
33,000 pound feet (not to be confused with ft/lbs) in one minute. = 1 hourse power. This could be 33 lbs moved 1000 feet in one minute or 3300 lbs moved 10 feet in one minute. All equals one hourse power.
Hope it helps.
Mikey D
Registered
Horse power is expresses as a number (162 HP) derrived from the above system.Yes, well we're getting there in a roundabout way...
We know how torque is expressed (force applied by 10 lb hanging off the end of a 1 ft bar -or- 1 lb hanging off the end of a 10 ft bar = 10 lbs/ft) - how about horsepower? How is horsepower expressed??
Steve
~~sigh~~Horse power is expresses as a number (162 HP) derrived from the above system.Yes, well we're getting there in a roundabout way...
We know how torque is expressed (force applied by 10 lb hanging off the end of a 1 ft bar -or- 1 lb hanging off the end of a 10 ft bar = 10 lbs/ft) - how about horsepower? How is horsepower expressed??
Steve
Yes, and that number is arrived at how??
Geez Mikey, you push the Socratic Method to the very edge, doncha...
Steve
Mikey D
Registered
The # is arrived at by taking the force applied, times the distance moved, by the time it took.~~sigh~~Horse power is expresses as a number (162 HP) derrived from the above system.Yes, well we're getting there in a roundabout way...
We know how torque is expressed (force applied by 10 lb hanging off the end of a 1 ft bar -or- 1 lb hanging off the end of a 10 ft bar = 10 lbs/ft) - how about horsepower? How is horsepower expressed??
Steve
Yes, and that number is arrived at how??
Geez Mikey, you push the Socratic Method to the very edge, doncha...
Steve
330 lbs X 100 feet / 1 minute = 33,000 pounds/feet in 1 min = 1HP
330 lbs x 100 feet / 2 minute = .5 HP
Remember, the force applied over the distance moved is vertical (against gravity) That would be an acceleration of 32 feet per second, per second.
Are we getting closer?
So, in context, we're talking force applied - torque figure - and the distance moved/time it took - rpm - divided by 5252 - conversion - equals a horsepower number.
Grab a calculator, take a look at a dyno chart and you'll see that it works.
As far as the semantics of 'same' goes, I agree - torque and horsepower are not the same, but the number used to express both quantities correspond at 5252 rpm.
Now go outside, sit in the shade and have a cold beer...
Steve
<!--EDIT|Aughtsix
Reason for Edit: "okay now, let's try this again..."|1090188316 -->
Grab a calculator, take a look at a dyno chart and you'll see that it works.
As far as the semantics of 'same' goes, I agree - torque and horsepower are not the same, but the number used to express both quantities correspond at 5252 rpm.
Now go outside, sit in the shade and have a cold beer...
Steve
<!--EDIT|Aughtsix
Reason for Edit: "okay now, let's try this again..."|1090188316 -->
Mikey D
Registered
Sorry 06 I cannot agree with yer calculations. It may accidently corrospond on certain Dyno chart, but they're all different.So, in context, we're talking force applied - torque figure - and the distance moved/time it took - rpm - divided by 5252 - conversion - equals a horsepower number.
Grab a calculator, take a look at a dyno chart and you'll see that it works.
As far as the semantics of 'same' goes, I agree - torque and horsepower are not the same, but the number used to express both quantities correspond at 5252 rpm.
Now go outside, sit in the shade and have a cold beer...
Steve
There is no direct conversion for torque to horsepower.
Torque is a twisting force and has no time component.
Horsepower is a measure of work and does include a time component.
I do however agree with the cold beer and shade thing!
Sooo....how do we convert shaves per minute?
You know, I've been thinking about the purpose behind the '5252', and I honestly can't recall. The formula was given to me years ago (mid 70's) by a high-performance engine builder. It's always seemed to work so I've stuck by it. I'm evidently not the only one who's heard it...Sorry 06 I cannot agree with yer calculations. It may accidently corrospond on certain Dyno chart, but they're all different.
There is no direct conversion for torque to horsepower.
Torque is a twisting force and has no time component.
Horsepower is a measure of work and does include a time component.
I do however agree with the cold beer and shade thing!
I agree that there is no time component for torque alone - in fact, the 10 lb/ft of torque given in the example above is still 10 lb/ft of torque regardless whether the nut moves or doesn't. Hang that 10 lbs from the 1 foot long wrench for all eternity and it's still 10 lb/ft of torque. But horsepower is an expression of work done, and that work required torque, so horsepower is an expression of what torque has accomplished over a given period of time - a function of torque and time.
Using your numbers let's work this out - help me out where I'm off:
33,000 lb/ft per minute = 1hp x 162 (for 162hp) = 5,346,000 lb/ft per minute divided by 10,000 rpm = 534.6 lb/ft per revolution.
Since in our 4 cylinder engines only 2 cylinders would have had power strokes in one revolution we divide 534.6 by 2 = 267.3 lb/ft per cylinder per revolution.
So in terms of horsepower we have one cylinder moving 267.3 pounds 1 foot per revolution.
A 2.4" stroke is only .2 of a foot, so divide 267.3 by .2 and we have one cylinder moving 1336.5 pounds .2 foot per revolution.
Then in terms of torque, we're hanging 1336.5 pounds off of our 2.4" shaft in order to move that 267.3 pounds 1 foot - so why doesn't the dyno reflect this huge torque figure?
Steve
Mikey D
Registered
YOu cannot divide lb/ft per min by RPM.
RPM has no linear or surface feet component. You would have to use the circumfrence of a diameter and change it to surface feet per minute.
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