HP vs. Torque

A co-worker and I had a discussion the other day. He says Torque wins races. I have always heard HP wins races. What do guys think?

 

I think torque is the only real number and horsepower is a number figured by multiplying torque by RPM divided by 5252.

 

Torque man, id take torque over hp anyday.

Id rather have 250hp and 500ft-lbs, than 500hp and 250ft-lbs.

Of course id have to have good rear-end and all, but u get my point.

 

Thanks for the formula on that. I always wondered how that worked. It appears that torque does play the bigger part here. My car puts out like only 170HP but about 255 foot-pounds of torque. I thought it felt faster than a 170HP would indicate. I found a great article on this:

http://www.edmunds.com/ownership/tec...4/article.html

 

Well, if you want to know the truth, neither is the deciding factor. Force is the only thing that makes the car go forward. Frictional force generated by the tire onto the road. Frictional force is instantaneous wheel torque divided by tire radius. Wheel torque is equal to gear torque. Rear gear torque is equal to the drivshaft toque times the rear gear ratio. driveshaft torque is equal flywheel torque times trans gear ratio. There is no torque loss through the drivetrain. There is power loss though. In an ideal world the power at the flywheel would equal the power at the wheels. There is a loss through friction though. Power is the amount of times a certain torque can be applied in a given amount of time. Power is also the amount of work that can be done in a given amount of time. Work is defined as a force applied over a given distance. So as you can see they are all related. Newtons second law mathematically is defined as: Force is equal to mass times the acceleration of that mass. So, what wins races is actually the biggest acceleration which is attained by the largest frictional force you can generate divided by the smallest mass(or weight) of the vehicle. From that you can find out how far you have traveled by using the equation d=1/2at^2+vt+d Then you also have to know the coefficient of friction of the tire to find the force propelling the vehicle. Then you have to calculate in wind resistance. I posted those equations under another thread. From that you can determine who wins.

Boil all that down and you get that a high power engine can use a larger rear gear which multiplies that torque. A high power engine also generally has a narrow torque band, you need more gears to keep it in that band. More gears rob more power and it takes more time to shift gears, even if it is only .05 secs in an F1 tranny. From that you have to determine if you power loss can make up for the extra torque multiplication you get from the rear. Then you need to see if your high torque engine, which is generally low speed, so it has a lower rear gear, has a higher wheel torque than your high speed engine. If you have an engine torque curve then you can use Excel to make a spread sheet to find out all of that fun stuff. After 4 years of school I can confidently say that it depends.

 

:hail:

Thanks man!! That was the best description yet. It'd be even better if I could follow all of it, but it defenitly helps!

Andy

 

torque for the 1/8th mile is best but we all need a little bit of horsepower when torque begins to be irrelevant at higher speeds...thats y civics run high traps but low ets...a HIGHLY MODDED civic

 

a lot of that has to do with it being FWD

they get a lot of wheel spin and can't launch hard off the line.... traction is a good thing to have for E.T but doesn't really affect traps





as far as hp vs torque I am a hp guy

I like to rev the engine and use gears to help me out

I have no torque down low peak torque stock is only 138 lbs/ft @ 3800rpms

but I also run lots of gear using a 4.10 to help out on that torque factor


I also just wonder why the F1 cars use little motors that might only put out 200 lbs/ft at there peak hp but around 800 peak hp
they have the gears to back it up though.....

 

Yep, at 18,000 or near there RPM it doesn't take a lot of torque to make a ton of power. I was watching a TV show and they had an F1 Cosworth engine on a dyno way back in the day. It was 22,000 RPM!! Now that was crazy. They have to use air bags instead of valve springs. I don't know how an engine even operates at those kinds of speeds.

 

Torque gets you going, HP keeps you going, simple as that

 

Are fieros rwd??? I know the fwd is bad for launches, i guess i coulda used a better example...btw im horsepower guy, i love those 281 Cobra engines.

 

The way i always explain TQ and HP is like this


Say I can carry 5 boxes of stuff and you can only carry 3 boxes. I have more Torque than you since i can carry more.

BUT

Say you can make 4 trips to the car in the time i can make 2. You make more HP since you carried 12 boxes outside while i only carried 10 boxes.

 

Yep.

 

Here's my version of TQ and HP:

The higher your horsepower the higher your top speed, therefore the faster you go.

The higher your torque the faster you accelerate, therefore the quicker you attain your high speed.


About F1 engines, since they spend most of their time maintaining high speeds, not really accelerating they dont need a lot of torque, but the do need a lot of horsepower.

 

F1 baby. Alright. 22000 RPMs is insane. But with 7 gears you can use it all. When my dad raced 3/4 midgets they used 4 cylinder 750 honda engines (yes honda). Those things could not be broken. It was a SOHC motor,4 carbs, header, balanced, no flywheel or tranny. It could do 12000 RPMs, then the valves would float. They made cams that would actually shut the valve too. They are expensive, but theoretically it has an unlimited RPM range. It made about 180HP with .75 liters of displacement!!! Crap for torque though. F1 uses all kinds of fun stuff, like ceramic pistons, plastic connecting rods, voodo variable timing.

 

my daddy and uncles and cuzins always said and i like the saying. hp sells engines but torque wins u the battles the races and gets tire companys happy :hail: :hail: