WW, does the motor pull well past peak power? I have found that running closer to the engine rev limit in the lower gears places you closer to the powerband in the next gear and ultimately allows you to go faster.
It pulls good up to the rev limit. The engine was kept at full throttle in 4th until it hit the rev limit and then it was shifted into 5th. This seemed to work best. Like you say, the late shift resulted in placing the shift into 5th gear higher in the power band.
I would "late shift" them all... the faster you get through the front part the faster you will finish
We generally shift near the rev limit in all but first gear, first will generally break traction at peak power and zoom to the rev limit.
OK, here are some visual graphics on why this works . . . . .
A/ It is the AREA under the portion of the bhp curve BEING USED, that determines how quickly a vehicle can be accelerated,
2/ Every vehicle requires some "range" of useable rpm, say 1500 to 2000 or so, rpm. This range can be "less" when the gear splits are closer together. But it is the "width" of the power band requirement, that defines the area under the curve for that particular engine or "tune",
d/ IF, the engine can be safely and reliably operated several hundred rpm above the peak power rpm, the above graph illustrates how a net "power under the curve" increase can be achieved. By shifting beyond the power peak, the resulting rpm drop then is higher on the power curve, resulting in faster acceleration, AND, potentially higher speed. UNTIL, power available = drag power being expended. Ie, drag hp in all forms.
z/ Obviously, taller, wider power bands should always be the goal. It's called "flattening the aspect ratio". Sometimes it is easy, mostly though, it is a challenge on reasonably well developed racing engines.
Bhp increases produced, are roughly equal to to the square of dollars spent. Early bhp gains are always the most cost effective. Later expenditures can become very expensive per bhp produced. Just the way it is . . . . . . F/b