DOnt understand how the S performance is the same as other cars with high Torque values higher than the S when wighter roughly the same, eg subarus wrx etc etc.

I though if a car had more torque and about the same weight it would be car x up a hill or in a straight line?

I know BHP is porportional to torque, and it the force upon the wheels make on the ground.

 

It's due to gearing.

Look at a bike engine, massive BHP per liter, but no torque. They get over this with high revs.

(Torque x Engine speed) / 5,252 = Horsepower

 

http://www.epi-eng.com/BAS-PwrTrq.htm

 

nice thanks

I have never really understood the relationship before!

 

Nice link Learn something every day here

 

Wise words

 

Or in a picture:



That's me crossed of the Christmas party list then

 

I've never used this formula, the one we always used to use was:-

2 X Pi x n x T = p where n = engine speed & T = torque
33000.00

This does work.

 

The key consideration that everyone forgets is that when we talk cars we talk engine figures. The S2000 has 240bhp and 161lbft of torque at its engine. A classic shape impreza has an engine output of 220bhp and 214lbft of torque and both cars weight about the same. Run these side by side from 40mph (to overcome traction advantage) and the S2000 will pull away.

The reason for this is that looking at the engine output in isolation is flawed because all the force it produces has a system of gearing to go through before its applied via the rubber to the road. The S2000's gearing is designed to specifically take advantage of the high reving f20c engine. The impreza also has to run it's engine power through more power sapping differentials before it gets to the road.

The key place to measure the force that an engine produces is at the wheels and preferably across the useable power range. On that note I'd bet my gran that the S2000 can achieve a greater overall wheel torque figure than the standard classic impreza despite the powerplant trailing by a significant margine. The ironic thing is that we take our cars to dyno's where wheel torque accross the useable power range of one of the higher gears is measured. The graph produced can tell us pretty much everything we'd ever want to know about the performance capabilities of our machine. However, we then extrapolate (i.e. guess) this information to generate an engine horsepower figure and that's what gets posted on the forums and touted around in the pub.

So in short a powerplant is just a component part of the overall machine and to gauge how that machine will perform you can't look at any component in isolation - crank torque, rpm, gearing, drivetrain, weight, drag co, etc all count towards final performance.

 

[QUOTE=mattlad,Nov 28 2006, 11:36 PM] I've never used this formula, the one we always used to use was:-

2 X Pi x n x T