On 08/04/2016 12:03, Dave Plowman (News) wrote:
Have said this countless times. But didn't stop others saying this was
wrong - or introducing countless red herrings and moving of goal posts.

It's what started the original thread and caused Vir to start this one.

But it seems he's not alone in having little understanding of basic
mechanics.

I am reading this, and I'll try one last time.

Torque is irrelevant to performance. I know it's hard for you to
understand, and it doesn't agree with your prejudices, but it's true.

For a car with a gearbox - and that is all of them - to get highest
performance you ignore peak torque, and keep the engine at maximum
power, or as close as you can get.

You can easily see this if you just work out the torque at the gearbox
output for these two cases
400nM at 2000RPM
200nM at 5000RPM
with ratios chosen to give the same speed at the output shaft - the
higher revs, lower torque will give you 25% more torque at any given
output speed of the gearbox.

It's true that if you can't change gear you'll get the highest
acceleration at peak torque. But that is not relevant to getting the
highest performance.

If you compare cars with similar peak torque outputs, but different
power outputs the performance won't match. But if you look at cars with
similar power outputs, but different torque outputs the figures will match.

Look here - BMW's 5 series
http://www.bmw.co.uk/en_GB/new-vehicles/5/saloon/2013/technicaldata.html

Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy