SameerP

so all things being equal which would be the better 0-60 car, and the better 1/4 mile car:

300hp/260 ft-lb
260hp/300ft-lb

Cheers,
Sameer

xr4tic

hp and torque are related, just depends on what RPM.

Torque is what does all the work.

If the peak HP > TQ that usually indicates a high RPM power band, whereas if peak TQ > HP, it usually indicates a mid RPM power band.

The two RPM bands require two different kinds of gearing to be optimized.

The fastest car will be the one with more area under the TQ (or HP) curve.

SameerP

let's go with the torquer making its torque at 3000 rpm, the hp car making its peak at 6000?


Cheers,
Sameer

Audi2ptzero

since your going to need to rev the car above 3000 to get going. Now if the 300 tq was at a peak of about 4500 it would be much better and have a much quicker 0-60.

Merkin

0-60 in 2nd gear hp would win

top end, HP would win

Alastor

<center><img src="http://pictureposter.audiworld.com/60072/powercurve.jpg"></center><p>I put this spread sheet together over lunch because I always enjoy HP vs. Tq debates. The information is in no way "the answer" but it does show a very simple solution. The primary problem with the spread sheet is the torque curve and resulting horsepower curves. Just knowing the peak HP or Tq is not enough, because the shape of the curves can have a drastic impact on results. I tried to make them as linear as possible. I only did 0-60 because it is not unreasonable to ignore friction and it can be done realistically in a single gear. The quarter mile is a completely different analysis. Anyway check it out and play with the numbers ;-)

xr4tic

let's say the HP peak is 5000 RPM for low-end torque example.

At 5000 RPM, you'd still have 273 ft-lbs of Torque

xr4tic

0 to 5200 RPM, low end TQ wins
5200 to 7000 RPM, high HP wins

<img src="http://pictureposter.audiworld.com/12130/hp_tq.jpg">

But in the end, it depends on how you gear your car.

SameerP

I guess i understand torque as twisting power, and HP as turning power.

So its torque's magic simply that it is an accelerating force developing at low rpms, and that more power at lower rpms best help standing starts?

Cheers,
Sameer

Kevin K2

in table, appears velocity is based on 18" dia tire, and force based on 24" dia tire?

also, torque is assumed to be at max value during each 1k interval .... would be more accurate to use average torque over the interval.

car2 with 24" effective tire dia

For 0-1000rpm interval:

ave torque = 50 ft-lbs, ave force = 300 lb

velocity at 1K = 17.45 ft/sec

average acc'n = 3.22 ft/sec^2

0-1k time = 5.4 sec

bottom line on initial Q, for given box and rpm range, it's basically the area under torque curve in usefull rpm range that matters.