On Tue, 05 Apr 2016 10:52:36 +0100, Dave Plowman (News) wrote:

Just to see if I was missing something that others found so obvious, I
asked this question on a forum designated to engine building and tuning,
etc.

'At what point on an engines output do you get maximum acceleration?'

And the answers were near unanimous. Peak torque.

I'll take the views of those guys over the bar room mechanics here any
day.

Ah! I see your problem now. If, as you've seemingly posed the question,
we're discussing, "When does the maximum instantaneous acceleration over
the operating rpm range of the prime mover occur in any *one* gear ratio
at a time?", then the answer to *that* question *will indeed* be at
maximum torque rpms.

However, since you used this little factoid to claim that the fastest
acceleration of a car can therefore only be achieved by making each
successive up-change at peak torque revs rather than at peak power revs,
you've immediately posed an entirely different more complex question
which now involves best gear selection choice versus engine revs to
maximise the acceleration of the whole vehicle.

I'm sure that, if you care to pose this completely different question to
the engine building and tuning forum, you'll get a different response,
one that matches what most in this NG have been trying to tell you,
seemingly to no avail over the past 8 days ever since you posted these
statements:

"And you'd get even more force at peak torque in that gear..."


You get the best acceleration with the maximum torque *at the wheels*. And
in any given gear, this will be when the engine develops maximum torque."

Whilst, on careful examination, both statements *are* strictly true, the
implied maximum acceleration requiring the engine to be held to its max
torque rpm as you progress through the necessary gear changes is patently
*untrue* since accelerating a mass involves raising its kinetic energy
which means its acceleration depends on the how swiftly you can increase
its kinetic energy which in turn is a function of energy rate or power.

I've been re-reading your subsequent posts and you seem to be purposely
avoiding this particular aspect of your implied question over best use of
gear changes versus max torque or BHP rev points to accelerate a car to
speed. Indeed, I spotted a statement where you seem to be trying to limit
the discussion to the engine alone sans the complications introduced by
the pesky transmission system.

Whether you were merely trying to introduce a confusingly phrased
assertion to stir things up or were confused yourself still isn't
entirely clear but I do have my suspicions that you were trying to 'Stir
up a Lively Debate' between mostly just yourself and the rest of the
group. If my suspicion is correct, may I be the first to congratulate you
"On a Job Well Done". :-)

--
Johnny B Good