Well,

*technically* speaking, from a mathematical point of view, you want to maximize the area under the power curve during the total acceleration time. The integral of power is work and so, by maximizing the area (integral) under the power delivery curve, you maximize the work done (maximize the car's speed after a "race".)

Though it's hard to believe, the power delivered to the wheels is roughly the same in each gear, ignoring loss differences between the gears. For example, a stock KL03 will turn roughly 135 peak HP to the wheels in 1st, 2nd, 3rd, 4th or 5th (or even reverse) gear on the dyno. Most people run in 3rd or 4th but the results don't vary that much. So to analyse this, you need to know what the power curve of the engine (FS, KL...doesn't matter) looks like (especially either side of the power peak), where the power peak occurs and what the gear ratios are for the transmission.

At the risk of oversimplification, you want to shift at the point the power delivery in you current gear falls below what it would be in the next gear. As you climb the RPM scale from the power peak in a given gear, the power output is dropping. When you shift, you'll end up dropping the engine RPM again, likely below the power peak. What you want is, if possible, to ensure that the power at the next gear's RPM (which will be RPM * nextratio/currratio) will be equal to or greater than the power at the RPM you are at now.

Imagine a dyno plot showing the HP at the wheels. Now imagine overlaying that with a "window" that can slide along the RPM scale. This window will vary in width for each pair of gears (1-2, 2-3, 3-4, 4-5) and will be this wide:

Width (RPM) = StartRPM * gear_a/gear_b

where

*gear_a* is the lower of the gear pair (1, 2, 3, 4) and

*gear_b* is the higher of the gear pair (2, 3, 4, 5). StartRPM describes where, RPM-wise, the window starts on the curve and indicates where the engine will land, RPM-wise, when you shift. The other end of the window, which is

*StartRPM + Width* wide, represents the current RPM in the current gear.

So... Let's take the 1-2 shift. 1st is about 3.35:1, 2nd is about 1.85:1 (I'm guessing here...can't recall the specs off the top of my head here at work.) So:

Width = StartRPM * 3.35/1.85 = StartRPM * 1.81

If you shift into 2nd gear and the RPM lands at, say, 3500, then you shifted from 1st at 1.81*3500 or 6335RPM. Does this shift maximize the area under the power curve? Probably not, because the power above 6335 is around 140HP and down at 3500, it's all the way down to 92HP (I'm using

my dyno run as the model for this example.) This is shifting too early since more power was available to scoot the car in the remaining RPM till redline in 1st then there is now in 2nd.

In cases like this, the RPM you shift at should be redline - or whatever you feel comfortable with up to the fuel cutoff. 1st-2nd is tough to idealize because the ratios are quite far apart. 2-3 and 3-4 are easier to get realistic numbers for since those ratios are quite close.

Having said all this, I think for the first two gears, redline or higher shifts are best for outright acceleration. For the higher gears, something just less than redline is best.

Corrections welcome