Sev

You should shift in a way that you are closest to your torque peak on the gear after the shift since that is when the car accellerates hardest, if hitting redline is the way to do it...

Luis

nope. You should upshift if

1) torque AT THE WHEELS is less than what it would be were you to shift at that moment,

OR,

2) if you're stubbornly bouncing against the rev limiter,

which ever comes first.

This is the general rule for all cars.

In the case of the S2000 you can ignore rule 1). It never happens.

cdelena

Luis, you haven't explained the 'forward force' chart on this board. Is it time for it?

Luis

Should I build a softbot that posts answers to these questions periodically?

Ok, I'll give it another go...

An analogy:

Imagine your car is pulled (not driven, it happens, it happens...) by a horse instead of an engine. What that graph shows is how much force the horse is exherting at various speeds in various gears. You have to realize that if the horse pulls harder, the car accelerates harder, right?

Now, how do you read the chart?

On the left vertical axis (Y axis) you read the amount of force the horse is applying.

On the bottom horizontal axis (X axis) you read the speed at which you're travelling.

The wavy lines represent the different gears.

To know how much force the horse is applying at a given speed you draw a vertical line at that speed.

Where it intersects with the wavy line that represents the gear you are on, you draw an horizontal line.

The point at which the horizontal line intersects the Y axis is the force being used to pull the car forward.

Example:

at 100 km/h in 2nd, the horse is pulling a bit over 600 kgf (it's a damned strong horse!). If at that point you decide to shift to 3rd, then the horse starts pulling about 450 kgf. If you were looking for best acceleration times, you would be better off to remain in 2nd til you run out of revs as the chart clearly shows.

Luis

You have read how Randy installed an ATS secondory reduction gear that gave him a 10% overall ratio reduction.

The chart shown above is no longer valid for his car. The wavy lines will now be taller (shifted up) by 10% but also compressed (not shifted) to the left by 10%.

RT

Luis, what are the 7 straight lines with decreasing positive slopes?

Luis

That's the gear ratios. For a given speed (horizontal axis) you find the corresponding RPM on the vertical right axis.

Now, someone else answers "what are the curved percentage lines?".