On 02/04/2016 01:56, Johnny B Good wrote:
On Fri, 01 Apr 2016 17:16:40 +0100, Dave Plowman (News) wrote:

In ,
Roger wrote:
Indeed they are. The rate of acceleration is dependent on gearbox
*output* torque - not on engine torque.

And the two are directly related.

Why is it impossible to see this? A gearbox simply multiplies the torque
of the engine.

I think we can all accept that as "A Given". However, for a given road
speed where the selected gearbox ratio matches the peak engine power
revs, you will gain a modest increase in torque applied to the driven
wheels compared to a ratio selected to allow the engine to run at peak
torque revs.

If we assume the theoretical case of a perfect stepless gearbox which
can automatically adjust the ratio to hold the engine to its peak torque
rpm as the road speed increases, you'll find that the resulting
acceleration will be less than one configured to hold the engine to its
peak power output rpm (it will operate at a larger reduction ratio in
this case which increases the torque applied to the road wheels compared
to the ratio range used to keep the engine operating at its maximum
torque rpm).


I couldn't have put it better myself!

In fact, I invited Mr Plowman to consider these two scenarios - with a
stepless transmission holding the engine either at its max torque point
or at its max power point - but he ruled it invalid because such
transmissions don't exist. My likely because it proved a point against
which he had no valid argument.
--
Cheers,
Roger
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