Talk to me about torque
 

Reading the EVO write up about the new GT3.

It weighs within 100kg of an STi. It has over 400bhp. It gets to 100mph in less than 9 seconds yet the torque figure is less than 300Ibft. Max torque is 5500rpm, pretty much the same as my old scoob, yet the scoob had more torque...... :wonder:

It has a much larger engine than the scoob, but no turbo.....So the turbo on the scoob would be increasing torque but I would have thought that would be offset by the extra displacement of the GT3 :wonder:

The GT3 is undoubtably a quicker car than the scoob, probably killing it in all in gear acceleration times, but without the torque how can that be?

I look forward to your wild and varied answers :lol1:

Gary

No heatsoak!! ;) :D :D

PS The GT3 ain as fast as me max'd Nova!! ;) :lol1:

Ns04

Dont forget its rwd and so does not suffer from 4x4 power losses

Im not talking about which is quicker .....far from it, just interested in why a bigger displacement engine with large BHP doesnt have a larger torque figure.

They [Porsche engineers] meant to put more torque it in, but got intoxicated on warm beer and sausages the nite before the launch??? ;) :D

Ns04

Its all about the turbo really.

A FI engine will always have less of a disparity between torque and BHP figures. Everyone bangs on about BHP but turbos really give you torque.

Probably easier to think of a similiar displacement / tuned NA engine. Say a civic type R. 200 BHP (so not a million miles off a scoob) but way down on torque.

If you look at supercars, all the AMG mercs, mclaren mercs etc that have foot/lb figures close to BHP figures are all blown. Look at a NA ferrari 430 for example and the torque again looks weedy.

So if you set up a test with both cars at 5500rpm and then put foot down would the one with more torque pull away or is that when BHP comes into the equation. That is assuming both have peak torque at 5500rpm

Also Aerodynamics?

Assuming they have the same figure for that also

Yep, you can't beat being blown!! :norty: ;) :D :D

BTW To extend the argument above: the 911 GT3 isn't too far away from the 911 Turbo in terms of BHP (IIRC), but significantly down on torque. How does the performance differ between the two?

Ns04

I also wondered that.

And shock horror the auto TT is quicker than the manual 0-60 & 0-100.

The 997 GT3 also looks nicer than the 997 TT imo.

So if you had two identical cars ......... One with 2 ltr engine 300/300 and a turbo. One with 3ltr engine 300/250 NA how would the figures compare I wonder?

Correct, as long as all the other things (wieght, tyre/road friction co-efficients etc) are the same.

In the same vein 2 cars with identical peak BHP figures and differing torque figures (but all other things equal) will have the same top speed.

As long as the car with the lower torque figure has the guts to pull it into the higher RPM range of course!

Torque is a function of BHP, so if 2 cars have identical peak BHP at the same revs, then the torque at that revs is the same!

Its the spread of power that counts. A turbo'd car may have a higher peak torque, but it can be in a part of the rev range where the power it produces isn't near max power.

At the end of the day a cars acceleration is a function of power available at the wheels, not the torque.

For example the F1 cars of last year were making 900 BHP at 18000 rpm, which equates to about 260 Lbft at the same revs!

The gearbox and well chosen ratios has alot to do with the acceleration of a vehicle.
A high reving, high hp, high torque engine with a flat torque curve from 0rpm to the red-line is what you need. Trouble is that is called a DC motor.

dipster

If you've got time to read it then this page tells you what you need to know about torque and horsepower:

http://vettenet.org/torquehp.html

Everyone goes on about torque being the b-all and end all for acceleration, so why aren't all sports cars diesels???

You also don't find alot of sports cars that only rev to say 5000rpm.

They do have a high power to weight ratio tho, (not necessarily a high torque to weight ratio) high power being easier to get from high revs