Torque vs Power viz-a-viz gearboxes

[domV8]

I wonder if any of the PH massive can help me understand gearboxes...

I have heard 2 statements which appear to me to be contradictory - and I am unable to resolve them..:

1. Engine (without gearbox) accelerates fastest at peak torque
2. Torque at the wheels is what accelerates the car

So firstly, it may well be that one of these is not correct..?

It is my understanding that a gearbox with take BHP (ie.torque at given revs) from the engine, reduce the revs by a factor of X and output the equivalently-factored amount of torque. This is what you would measure as torque at the wheels... (?)

So from that, I would take away that my highest torque-at-the-wheels value would be my highest BHP value..?

That does not agree with the first of the 2 statements above...

So can someone tell me how this works - with regards to torque at the wheels, fastest acceleration point in the range, and torque vs. BHP...?


Thanks!


Dom

[domV8]

Hi Benjamin, thanks for the reply
Unfortunately, I am still none-the-wiser

So we know that power is a function of torque, as a fraction of 5252 rpms - ie. Torque at given revs.

Now a gearbox takes torque at revs, and then adjusts revs to output an adjusted torque value...

This adjustment of revs & torque sounds to me like BHP, but a RR measures torque at wheels not BHP - so what's actually happening here?

If a gearbox in fact adjusts BHP, then am I best changing at max BHP (hence motorbike engines, high revving 2l engines etc) - or if it adjusts torque, should I be changing at max torque?

Or if it in fact changes BHP into torque (ie. multiple engine resolutions into a single measured output rotation), then what? Aaaaagh! Confused!

What is happening in a gearbox, and how do I make best use of it?

Thanks,

Dom