On 05/04/2016 21:40, michael adams wrote:
"Roger wrote in message
...
On 05/04/2016 15:35, michael adams wrote:


Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin. As many boy racers at traffic lights know
to their cost, never mind many stars in reasonably prices cars*.
And the same would presumably also apply in wet or icy conditions*
at much higher speeds

Not that the same doesn't apply equally well to torque.

Well yes, of course. But I think we're assuming we have a dry road with plenty of
adhesion.

Indeed, but how would those two conditions prevent wheelspin between
say 1mph and 5mph ?


They wouldn't. The argument about whether you get max acceleration by
using max torque from the engine or max power with a lower gear only
applies when there is sufficient adhesion to use full throttle without
wheelspin. If there isn't, you get maximum traction when the wheel is on
the point of slipping but not slipping. To achieve this you need to
reduce the power output and/or apply the brakes to the driving wheels.
Many modern cars do this automatically by integrating engine control
with the (anti-lock) braking system.
--
Cheers,
Roger
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