explanation please
Discussion
The How Things Work website can probably explain it better than I can.
http://auto.howstuffworks.com/horsepo
http://science.howstuffworks.com/fpte
Hope those links are helpful...
http://auto.howstuffworks.com/horsepo
http://science.howstuffworks.com/fpte
Hope those links are helpful...
Edited by Trooper2 on Sunday 25th February 09:31
Perhaps this explains the torque/HP relationship a little better.
Extract with thanks to Wikipedia http://en.wikipedia.org/wiki/Torque
In the equation above there is the constant 5252 and this will be noticed in any graph of HP and torque plotted at the same scale. Both lines will always cross on the graph at 5252rpm.
Torque is grunt. Torque spins wheels and breaks drive shafts. When revs are added to the formula you get the work or HP.
If you play with the formula you can see that an engine producing good torque but lowish rev limit (typically a V8 with a long stroke) can be beaten on HP with an engine producing less torque but with high revs (Typically a bike engine).
The adage 'no replacement for displacement' comes from the Americans need for torque in order to shift 2 ton cars. On the other hand is the BEC where the HP at high revs works just fine as the car is so light but does not have that 'grunt' at low revs.
Steve
Extract with thanks to Wikipedia http://en.wikipedia.org/wiki/Torque
In the equation above there is the constant 5252 and this will be noticed in any graph of HP and torque plotted at the same scale. Both lines will always cross on the graph at 5252rpm.
Torque is grunt. Torque spins wheels and breaks drive shafts. When revs are added to the formula you get the work or HP.
If you play with the formula you can see that an engine producing good torque but lowish rev limit (typically a V8 with a long stroke) can be beaten on HP with an engine producing less torque but with high revs (Typically a bike engine).
The adage 'no replacement for displacement' comes from the Americans need for torque in order to shift 2 ton cars. On the other hand is the BEC where the HP at high revs works just fine as the car is so light but does not have that 'grunt' at low revs.
Steve
that's a good one I've not heard it before!torque times speed = power
more torque = more power (american V8's)
more speed = more power (Honda Vtec, F1)
intergrate the area under the curve between gear shift is the true measure of an engines power then average
some people think having more torque is better as you dont have to convert as much but that is what gearboxs are for
more torque = more power (american V8's)
more speed = more power (Honda Vtec, F1)
intergrate the area under the curve between gear shift is the true measure of an engines power then average
some people think having more torque is better as you dont have to convert as much but that is what gearboxs are for
steve_d said:
Torque is grunt. Torque spins wheels and breaks drive shafts. When revs are added to the formula you get the work or HP.
If you play with the formula you can see that an engine producing good torque but lowish rev limit (typically a V8 with a long stroke) can be beaten on HP with an engine producing less torque but with high revs (Typically a bike engine).
If you play with the formula you can see that an engine producing good torque but lowish rev limit (typically a V8 with a long stroke) can be beaten on HP with an engine producing less torque but with high revs (Typically a bike engine).
...but remember that torque can be multiplied and divided by gearing. An analogy that I've used before:
It takes a certain amount of work (horsepower) to move a pile of bricks from one place to another...
A little skinny guy might do it by picking up one brick at a time running to the destination, then running back to collect another one. He's the motorcycle engine... his rate of work (horsepower)relies on speed rather than strength.
A big powerlifter might move the bricks by picking up the whole pallet at once, then stomping slowly and deliberatly to the destination with them. He's the american Big Block... his rate of work relies on strength rather than speed.
Put both guys on bicycles, with gears, and their top speed (which is basically dependent on horsepower) might be the same, but the little guy would be pedalling like fury in a low gear, whereas the powerlifter would achieve exactly the same speed by pedalling slowly but forcefully in a much taller gear.
It becomes a bit more complicated with acceleration, 'cos you've got to take into account things like the inertia of rotating components, but as a general rule torquey engines have an advantage because they can 'pull' harder in a given gear... high speed, low torque engines need lots of gears to make sure they don't drop out of their narrow optimum rev range.
Bike engines in cars - even light cars - only work well when they are given absurdly short gearing to compensate for their relative lack of torque.
chassis 33 said:
Does anyone agree with this very simple analogy ...
Torque is a measure of how strong your engine is.
Power a measure of how fit your engine is (or how well you can use your strength)
Torque is a measure of how strong your engine is.
Power a measure of how fit your engine is (or how well you can use your strength)
I can see where you are coming from, but I'd say that BMEP is a better measure of how 'fit' your engine is.
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