Optimum shift points for performance

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Originally Posted by seangti

Anthony, from my understanding, the outcome to your approach would really only be applicable to reach that arbitrary figure or distance. So for quarter mile, shifting at optimal points for 1st and 2nd gear would accelerate faster than holding onto them till cutout, but holding 3rd to cross the line may be faster. Reason being, that once the gear is beyond it's efficient power delivery, the next gear WILL accelerate faster. This is probably best explained in the g-force graph, post 5800rpm for me, 3rd gear pulls more g's, which is accelerative force.

Also perhaps worth bearing in mind that each manual shift takes an average of 0.8 seconds which is also backed up from some runs I've done and Ben (aka Machine in his Golf R). If you run similar tests to me in gears 1-4 stretching them out to cut out using gtech (I'd need the raw data so must be the RR version), I could reasonably easily model the differing quarter mile times pending shift points. Though I'm not keen revving my car into/beyond red line, though your mods and tune may/could likely yield differing results to my entry stage 1 level of mods.

I had some discussion on the mkVl forum comparing DSG to manual (specific to R's), DSG shifting in about 0.1 secs. That doesn't mean you lose 0.7 off your time per shift, just 0.7 of full throttle per shift, I.e. robbing 1.5+sec of foot to floor board over a ~14second run.

Food for thought hey. (PS, if Im interpreting any of the data incorrectly, please correct me)

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No you're correct. I shift first at about 5500-6000 in first on the 1/4 and 6-7000 for the 2nd - 3rd. But as you stated a gear shift can rob you of .7 seconds so my logic for the quarter with the SQS gear set is save the time loss from the 3rd to 4th gear change but continue velocity over the line in 3rd by revving out to 7000rpm and therefore hitting a trap speed at that point of around the 179kph mark.

As opposed to 160kph and coasting over the line :emo_baghead: There has to be a few 10ths in that I would think.

Hey guys, I will put my non-scientific but personal experience into this. I am honestly finding for qtr miles runs even with mods there is no point revving beyond 6grand. Obviously I am not quick enough to do this in first, but every other gear change I try my damndest to keep it under that mark and seems to work ok.

Power and torque curves have to be read very carefully.

Generally, the curves are obtained at wide open throttle. The curves will change depending on the percentage of throttle used, and so you have to look at them to work things out properly. The part throttle curves can be very different to the wide open throttle curves.

yes. understood. torque peak shifts lower down the rev range with less throttle due to pumping losses being constant vs power produced per stroke decreasing.

This thread is about maximising acceleration so unless the car has very bad tuning of some sort so it's stumbling at some point of the rev range, then WOT is a given.

Back on topic, for peak performance, you generally want to shift past the power peak so that the engine has delivered the most that it can and you would like to shift into as high in the power curve as possible so the engine keeps driving as hard as possible. The torque peak (where the most energy is delivered per stroke) is basically irrelevant as it is the RATE of energy delivery is what matters (the actual definition of power) and this is the product of the energy is delivered per stroke x number of strokes (torque x rpm).

Operational impediments are the only reason the don't do this when trying to maximise acceleration.

Going beyond the redline is a bad idea from the engine longevity point of view and also many engines will drop power dramatically beyond the power peak any way (be it naturally or with rev limiters).

jasn78, at what rpm does your engine deliver peak power?