Calculating Shift Points
#1
Calculating Shift Points
I dusted off an old software project today. A year ago I wrote a small app that given tire size, gear ratios, final drive, and a redline, would calculate such things as top speed in each gear, as well as rpms in the next gear after a shift. Not rocket science; it was more of an exercise to make sure that I understood the principles.
I broke out the code today, and wrote a quick import routine to suck in DynoJet run files that have been exported to CSV. I then wrote a simple shift calculating function. It takes a gear, and loops through the rpm in that gear up until redline. At each rpm increment, it multiplies the measured horsepower from the dyno file by the gear ration. It then calculates the rpms for the next higher gear. From there, it looks up the horsepower for that rpm in the next gear from the dyno file, then multiplies the horsepower by the next gear's ratio. If the horsepower in the next gear is greater than the horsepower in the current gear, then that's the shift point.
Using that algorithm and my latest run file, my shift points are 7100, 7100, 7050, and 7100. That's based on a dyno where 7100 rpms was the highest measured value.
So for those smarter than me, does this calculation make sense?
I broke out the code today, and wrote a quick import routine to suck in DynoJet run files that have been exported to CSV. I then wrote a simple shift calculating function. It takes a gear, and loops through the rpm in that gear up until redline. At each rpm increment, it multiplies the measured horsepower from the dyno file by the gear ration. It then calculates the rpms for the next higher gear. From there, it looks up the horsepower for that rpm in the next gear from the dyno file, then multiplies the horsepower by the next gear's ratio. If the horsepower in the next gear is greater than the horsepower in the current gear, then that's the shift point.
Using that algorithm and my latest run file, my shift points are 7100, 7100, 7050, and 7100. That's based on a dyno where 7100 rpms was the highest measured value.
So for those smarter than me, does this calculation make sense?
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