On 04/04/16 23:09, Roger Mills wrote:
On 04/04/2016 21:42, Vir Campestris wrote:
On 04/04/2016 18:59, Roger Mills wrote:

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.

I thought the idea was to run so far past peak power that when you
changed up you were at the same power output the other side of the peak?
So no steps?

Andy

That would be the ideal, and may be achievable if you have a lot of
closely spaced gears. Otherwise you're likely to reach valve bounce or,
in the case of a diesel, hit the governor before reaching the point
where the next gear up will allow the engine to produce the same amount
of power.

In all the calculations I did when I was doing this for a living -
albeit a few decades ago - the next gear up always dropped you further
down the power curve. When doing a practical road test, you could
counter that to some extent by not letting the engine revs drop during
the gear-change so that you got an inertial 'kick' when you let the
clutch in.

That reminds me of one factor which we had to include in performance
calculations which hasn't been discussed here - namely the effect of the
engine's own moment of inertia. In a low gear, quite of lot of engine
torque is used up accelerating the engine itself - reducing the amount
available for accelerating the vehicle. The "effective mass" of the
engine, which was different for each gear, had to be added to the
vehicle mass when calculating acceleration.

Balanced lightened flywheel/crank lightened pinions..BTDTGTTS


--
Bureaucracy defends the status quo long past the time the quo has lost
its status.

Laurence Peter