Optimum shifts

[Helge Wunderlich]

On Sat, 20 Apr 2002 18:49:59 +0200, gerard wrote:
>I might be wrong here, but one has to consider the fact that race cars
>usually have all the torque and power way up in the rev range and
>they're usually quite close together

In any engine, the power peak will *always* be at a higher rev than
the torque peak. While it would be theoretically possible to design an
engine with the power and torque peaks close together, a practical
combustion engine is never like that.

People who race completely stock street cars also go all the way to
redline when they want max acceleration.

If you were to try an F1 car or a GP1 bike, you'd be *amazed* at the
extremely wide and smooth power band of the engines. Power is
worthless if the driver/rider can not make use of it, so sacrificing
some peak power to get a wider power band makes complete sense.

>and the cars run some close ratio
>boxes.

It is correct that if you have a transmission with extremely close
ratio gears, you would shift somewhere between power peak and redline
to get max acceleration, but in practice, you'd waste so much time
changing gears that the advantage would be more than outweighed.

>I'm sure they don't think of where to shift exactly all the time,
>they just gun it until it's dead as the cars have been built with all
>the power and torque way up there.

They don't think consciously about it, it's completely "in their
bones". They also have lights to help them decide when to shift. I
watch F1 sometimes, and occasionally, when a driver has a very safe
lead towards the end of the race, they shift a couple of hundered revs
lower to protect the engine. When they do, you can see the lap time
increasing by several tenths right away. I'd say a race driver shifts
with extreme precision.