HP and Torque

[99Camaro99]

I know what they are but how do they affect a race or a 1/4mi run.

What's the difference if you have lots of torque but no horsepwer

or if you have no torque and tons of horsepower.

Explain please!

[carldev96]

This page is the bomb...

http://www.vettenet.org/torquehp.html

check it out

carldev

[Skullcamaro]

Horsepower is a derivative/part of torque. Their is an equation that determines how much horsepower you have based on the amount of torque you have. I can;t remember what the equation is off hand. I'll see if I can find it later.

[Shadly]

I remember something about small block Chevys. Hot rodders used to make 383ci engines out of old junk yard engines for racing. Depending on the application, they would match up a 350 block with a 400 crankshaft to give lots of HP and match up a 400 block with a 350 crankshaft to give lots of torque. I think I have this right.
Big bore + small stroke = Torque
Big stroke(huh,huh)+ small bore = Horsepower

You would build a really lightweight, high horsepower machine for drag racing, but for street or racing doorslammers, you would build a torque monster.

[Dominic]

you're backwards.

The longer the stroke, the lower the redline (for a given material), and the more lowend torque less highend racing horsepower.

The shorter the stroke, the more highend horsepower due to increased redline, and the less bottomend torque.

Bore affects MANY many things... the larger the bore, the more valve area the cyl can have and the better it can breathe. However, increasing bore increases the contact-surface area of the engine, which increases the internal friction of the engine, and robbs horsepower. So, there is a range of piston bore to stroke ratio you must make an engine be in in order to maximize efficiency.

Too much bore, not enough stroke, and you wont even burn rubber until 15,000RPMs.

too little bore, too much stroke, and she'll move a lot, break easily due to the movement, be difficult to balance and wont breathe worth a damn [img]smile.gif[/img]

[Shadly]

Yeah, that sounds better. I've got a book on all this crap at home. I think, with all these new engines out now, I won't really have to worry much about boring a block.

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by 99Camaro99:
What's the difference if you have lots of torque but no horsepwer

or if you have no torque and tons of horsepower.
<hr></blockquote>

The difference is one is a Chevy pickup, and one is a Formula 1 racecar.

carldev96 posted the best article you can get if you want to know about HP v ftlbs.

For lazy people, the equation is HP = Torque*RPM/5252

EDIT: I orriginally used the S2000 as my example, but it doesn't make "tons" of hp, so I changed it to F1.

[ April 09, 2002: Message edited by: HAZ-Matt ]</p>

[Shadly]

<blockquote>quote:</font><hr>Originally posted by carldev96:
This page is the bomb...

http://www.vettenet.org/torquehp.html

check it out

carldev<hr></blockquote>
I love this article. I stumbled across this a few years ago on an Olds 442 site. When that went away, it somehow made it to vettenet and an Impala site.

[V6Bob]

FWIW, let me try a short version.

1. The only thing that ever matters is torque AT THE REAR WHEELS, or how hard you're twisting the rear wheels. Torque ATRW is engine torque multiplied by transmission ratio, multiplied by rear end ratio.

2. You can design an engine to make power at lower rpm or at higher rpm. The first is what is usually called a "torque" motor. Its' torque number will be impressive and it will be at a low rpm. The second is called a horsepower motor. Its' torque number will be a little less, but it will be at a much higher rpm.

3. At any given speed, say 60 mph, you can run a much lower gear with a horsepower motor. Its' torque ATRW will be greater than that of the torque motor.

4. So why isn't a horsepower motor always better? The thing people tend to forget is you can't always run the motor at one rpm, it has to run at a range of rpm. And a horsepower motor has a narrower range where it puts out power. The ultimate in horsepower motors were the old 50cc GP motorcycle engines. 3 cubic inches, 15HP, and they needed 15 speed gearboxes to keep the engine where it could work. Modern F1 cars have seven speeds, same reason.

5. The NASCAR boys, not wanting to shift, build different motors for different tracks. Michigan, narrow speed range, horsepower motor. Darlington, big speed range, torque motor. The speed range is what counts, not the actual speed.

5. Getting back to the original question: for the street, horsepower motor, goes fast, needs big rear gears to work, needs to be shifted a lot. Torque motor, slower, but doesn't need as many shifts or to be revved as high (high revs cause noise, vibration, bad gas mileage).

Probably more than you wanted to know :D .

[ April 09, 2002: Message edited by: V6Bob ]</p>

[99Camaro99]

so I guess it's good the L36 makes max torque at 4,000RPMs [img]smile.gif[/img] (not 2,800rpm like the LT1)