diff between torque and HP

[mrbacardi]

ok, i've searched it on the net, but no real good explanation.

The only thing that i kinda got was that the numbers for HP were kinda useless and they depend on the torque, and torque is the independant factor.

But the question i am asking is, what gives you better acceleration, HP, torque or both. How? Why?

Thanks,
Dan

[rezzle]

F=ma
Force = mass x acceleration.

Torque is amount of 'twist' the engine puts out ... the force.

P=Fd
Work (power) = force X distance

Horsepower is a measurement of the application of the torque.

[mrbacardi]

Originally posted by rezzle
F=ma
Force = mass x acceleration.

Torque is amount of 'twist' the engine puts out ... the force.

P=Fd
Work (power) = force X distance

Horsepower is a measurement of the application of the torque.

your force formula is correct, however your power formula is incorrect.

Power is the rate of doing work, they aren't the same thing.

Work = Force x distance
Power = (Force x distance)/time
Torque = (Force x (perpendicular distance))

these are the correct formulas, i know they are correct cause i am in university and finished a mechanics course last year.

But anyways, anyone have a formula or something for calculating the acceleration of a car knowing the mass, torque and HP levels. (We'll assume ideal conditions, ie horsepower at the wheels = HP at the crank)

Thanks,
Dan

PS please use SI units like the rest of the world does...

[Nick]

Originally posted by mrbacardi
PS please use SI units like the rest of the world does...

in that case you should be asking about Kilo watts/hour then... not hp.... :p

[mrbacardi]

Originally posted by Oldman


in that case you should be asking about Kilo watts/hour then... not hp.... :p

dammit you got me there

now i feel stupid cause i thought i was so smart in the previous post, but whatever, you are still wrong, there's no such units as Kilowatts/hr

Kilowatts = KJ/s

usually power is expressed in Kilowatts

hehe whatever, anyone come up with a formula or something yet?

[Nick]

i've got it in old physics books somewhere, but they're packed away in boxes with most of my stuff...

[Phi]

Interesting read;

http://www.isimpression.net/forum/viewtopic.php?t=1570

[alltrac165]

Well, the formula for hp is
HP=(Torque x RPM)/5252
So HP is a function of torque and rpm. On any dyno chart, at 5252 rpm, the torque and HP should also be the same as a side note.
Go here for an online calculator you can play with.
http://www.speedworldmotorplex.com/calc.htm
Torque moves the car. HP tells us our accelleration capability to a degree. Generally speaking, higher torque at lower rpms feels faster and is more fun on the street as the power is in a range you spend more time in. When you can run whatever gear ratio you want, and aren't worried about spinning the crap out of your engine, then only HP matters.
Here's another link to more calculators than you will ever need.
http://www.csgnetwork.com/automotiveconverters.html

Or you can just read the link Chris posted above. That explains it better and in much detail.

[rezzle]

Originally posted by mrbacardi


your force formula is correct, however your power formula is incorrect.

Power is the rate of doing work, they aren't the same thing.

Work = Force x distance
Power = (Force x distance)/time
Torque = (Force x (perpendicular distance))

these are the correct formulas, i know they are correct cause i am in university and finished a mechanics course last year.

But anyways, anyone have a formula or something for calculating the acceleration of a car knowing the mass, torque and HP levels. (We'll assume ideal conditions, ie horsepower at the wheels = HP at the crank)

Thanks,
Dan

PS please use SI units like the rest of the world does...

Caught me sleeping .. thanks.

I know of two programs.

This one ... very simple it assumes RWD and is VERY close for RWD cars.
http://www.nismo.org/test/quartermil...bs=2450&hp=345

and this one ...

http://www.geocities.com/extrememr2s/mr2main.htm
Download the dos app at the bottom of the page the numbers are close, about a 1/4 second off.

Sorry they are both in imperial units.

[mrbacardi]

thanks everyone, cleared it all up and that program kicks ass

[Chris Corolla S]

These links should be in the master sticky...