direct relationship between horsepower and torque
07-09-2005, 01:34 AM
#1
Registered User
Thread Starter
direct relationship between horsepower and torque
I just found this and could not believe how truely close this comes...
I guess I just had to much time on my hands tonight. I know most of you know at what RPM you are hitting peak power, But, Based off of my Dynos in my gallery that showed MPH instead of RPM, I decided to give it a shot: I wanted to know my RPM vs. Power
889.49 * 2844 / 5252 = 481.665
TRQ-----RPM---------- HP
There is a direct relationship between horsepower and torque. You can convert torque to horsepower with the following equation:
HP = Torque * RPM / 5,252
That 5,252 number, by the way, comes from dividing 33,000 by (2 * pi).
Imagine taking 33,000 foot-pounds and walking it around in a circle rather than a straight line. For example, if you took a 10 foot pole and attached it to a vertical axle, the circumference of its circle is: circumference = 10 * 2 * pi = 62.8 feet
If one horse is pushing on the pole with 100 pounds of force (1,000 foot-pounds of torque), it can move the pole at 5.25 RPM. Torque and horsepower are directly related to each other.
You can see from the horsepower equation that high RPM values favor horsepower. If you take an engine with a certain torque and run it at very high revs, it can generate lots of horsepower even though its torque hasn't changed at all. A racing engine can produce relatively low torque, but because it can rev so high it gets a great horsepower rating. A big diesel has huge torque, but "gets no respect" in terms of horsepower because it cannot ever get above 2,000 RPM. This "makes sense" -- if two engines produce the same torque, the one that can do it more times per minute does more work and therefore has more power.
The difference in maximum RPM ratings also tells you why trucks need so many gears. A race car engine might idle at 1,000 RPM and can accelerate to 15,000 RPM -- a multiplier of 15. A big diesel might have a multiplier of only 2 or 3. Because the RPM range between minimum and maximum is so small on a diesel, there needs to be lots of different gears to keep the engine in its productive RPM range at any speed.
I guess I just had to much time on my hands tonight. I know most of you know at what RPM you are hitting peak power, But, Based off of my Dynos in my gallery that showed MPH instead of RPM, I decided to give it a shot: I wanted to know my RPM vs. Power889.49 * 2844 / 5252 = 481.665
TRQ-----RPM---------- HP
There is a direct relationship between horsepower and torque. You can convert torque to horsepower with the following equation:
HP = Torque * RPM / 5,252
That 5,252 number, by the way, comes from dividing 33,000 by (2 * pi).
Imagine taking 33,000 foot-pounds and walking it around in a circle rather than a straight line. For example, if you took a 10 foot pole and attached it to a vertical axle, the circumference of its circle is: circumference = 10 * 2 * pi = 62.8 feet
If one horse is pushing on the pole with 100 pounds of force (1,000 foot-pounds of torque), it can move the pole at 5.25 RPM. Torque and horsepower are directly related to each other.
You can see from the horsepower equation that high RPM values favor horsepower. If you take an engine with a certain torque and run it at very high revs, it can generate lots of horsepower even though its torque hasn't changed at all. A racing engine can produce relatively low torque, but because it can rev so high it gets a great horsepower rating. A big diesel has huge torque, but "gets no respect" in terms of horsepower because it cannot ever get above 2,000 RPM. This "makes sense" -- if two engines produce the same torque, the one that can do it more times per minute does more work and therefore has more power.
The difference in maximum RPM ratings also tells you why trucks need so many gears. A race car engine might idle at 1,000 RPM and can accelerate to 15,000 RPM -- a multiplier of 15. A big diesel might have a multiplier of only 2 or 3. Because the RPM range between minimum and maximum is so small on a diesel, there needs to be lots of different gears to keep the engine in its productive RPM range at any speed.
07-09-2005, 12:04 PM
#6
Registered User
Join Date: Apr 2005
Location: Surprise, AZ
Posts: 131
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by mikmaze
ok, next question on the quiz.... how many btu's are in a HP? extra credit: KW in a HP?
ok, next question on the quiz.... how many btu's are in a HP? extra credit: KW in a HP?
Trending Topics
07-09-2005, 01:45 PM
#8
Registered User
Thread Starter
BTU's in One Horsepower for one hour is I believe 746 watts. Which is about 2,545 BTU's.
Now how many calories would a horse consume if used 100% efficiently in 1 hour?
Totally Needless info....
Now how many calories would a horse consume if used 100% efficiently in 1 hour?
Totally Needless info....
07-09-2005, 02:17 PM
#9
Registered User
Originally posted by CrashCade
BTU's in One Horsepower for one hour is I believe 746 watts. Which is about 2,545 BTU's.
Now how many calories would a horse consume if used 100% efficiently in 1 hour?
Totally Needless info....
BTU's in One Horsepower for one hour is I believe 746 watts. Which is about 2,545 BTU's.
Now how many calories would a horse consume if used 100% efficiently in 1 hour?
Totally Needless info....
And don't forget to add the calories burned for the shovel work afterwords
07-09-2005, 09:19 PM
#14
Registered User
Join Date: Jul 2004
Location: west central Florida
Posts: 566
Likes: 0
Received 0 Likes
on
0 Posts
Horsepower is a measure of work done over time such as moving 17,000 lbs 70 miles in an hour. In our application we use torque and rpm to make horsepower. The high torque low rpm Cummins makes the necessary hp at around 1800rpm. My Hemi powered Ram needs to run about 3,200rpm to produce the same hp and uses gear reduction to multiply torque to the rear wheels equal to that of the Cummins powered Ram. I would need to change my gear ratio to 4.56 like the PowerWagon to do this. At about 65mph the following power is available.
610ft/lbs X .69 O/D X 3.73 = 1570ft/lbs at the rear wheels
610ft/lbs X 1800rpm/5252 = 209hp
The Hemi at 3200rpm
350ft/lbs X 1(direct drive) X 4.56 = 1596ft/lbs to the rear wheels
350ft/lbs X 3200rpm/5252 = 213hp
Of course the obvious is, the Cummins will be just broke in good when the Hemi is about to retire, it does it at a far more relaxed rpm and uses about 30% less fuel to do it. That's why most normal people prefer the Cummins for towing. But the relationship between horsepower and torque is simply, horsepower is torque X rpm in our application.
HID, Here's wishing you and yours a safe Sunday with Hurricane Dennis heading your way. We just left DeFuniak Springs Friday and came home to Tampa. Our daughter lives a few miles out of Florala. That's waaaaayyyy out in the sticks...
610ft/lbs X .69 O/D X 3.73 = 1570ft/lbs at the rear wheels
610ft/lbs X 1800rpm/5252 = 209hp
The Hemi at 3200rpm
350ft/lbs X 1(direct drive) X 4.56 = 1596ft/lbs to the rear wheels
350ft/lbs X 3200rpm/5252 = 213hp
Of course the obvious is, the Cummins will be just broke in good when the Hemi is about to retire, it does it at a far more relaxed rpm and uses about 30% less fuel to do it. That's why most normal people prefer the Cummins for towing. But the relationship between horsepower and torque is simply, horsepower is torque X rpm in our application.
HID, Here's wishing you and yours a safe Sunday with Hurricane Dennis heading your way. We just left DeFuniak Springs Friday and came home to Tampa. Our daughter lives a few miles out of Florala. That's waaaaayyyy out in the sticks...
07-09-2005, 10:39 PM
#15
Registered User
Thread Starter
[QUOTE]Originally posted by Hannibal
Horsepower is a measure of work done over time such as moving 17,000 lbs 70 miles in an hour. In our application we use torque and rpm to make horsepower. The high torque low rpm Cummins makes the necessary hp at around 1800rpm. My Hemi powered Ram needs to run about 3,200rpm to produce the same hp and uses gear reduction to multiply torque to the rear wheels equal to that of the Cummins powered Ram. I would need to change my gear ratio to 4.56 like the PowerWagon to do this. At about 65mph the following power is available.
610ft/lbs X .69 O/D X 3.73 = 1570ft/lbs at the rear wheels
610ft/lbs X 1800rpm/5252 = 209hp
The Hemi at 3200rpm
350ft/lbs X 1(direct drive) X 4.56 = 1596ft/lbs to the rear wheels
350ft/lbs X 3200rpm/5252 = 213hp
Of course the obvious is, the Cummins will be just broke in good when the Hemi is about to retire, it does it at a far more relaxed rpm and uses about 30% less fuel to do it. That's why most normal people prefer the Cummins for towing. But the relationship between horsepower and torque is simply, horsepower is torque X rpm in our application.....
As originally stated...... I think..... But wow, apparently this is a slow Saturday. This one lost me.
Horsepower is a measure of work done over time such as moving 17,000 lbs 70 miles in an hour. In our application we use torque and rpm to make horsepower. The high torque low rpm Cummins makes the necessary hp at around 1800rpm. My Hemi powered Ram needs to run about 3,200rpm to produce the same hp and uses gear reduction to multiply torque to the rear wheels equal to that of the Cummins powered Ram. I would need to change my gear ratio to 4.56 like the PowerWagon to do this. At about 65mph the following power is available.
610ft/lbs X .69 O/D X 3.73 = 1570ft/lbs at the rear wheels
610ft/lbs X 1800rpm/5252 = 209hp
The Hemi at 3200rpm
350ft/lbs X 1(direct drive) X 4.56 = 1596ft/lbs to the rear wheels
350ft/lbs X 3200rpm/5252 = 213hp
Of course the obvious is, the Cummins will be just broke in good when the Hemi is about to retire, it does it at a far more relaxed rpm and uses about 30% less fuel to do it. That's why most normal people prefer the Cummins for towing. But the relationship between horsepower and torque is simply, horsepower is torque X rpm in our application.....
As originally stated...... I think..... But wow, apparently this is a slow Saturday. This one lost me.