You ask too many questions :) The batteries should be treated like 1.0v per cell underload when doing your calculations. 1940 motor will be plenty, and you can can plumb in the different gear ratios / motor turns into the speed calculator to come up with some answers. Just remember that 40,000 rpms is the target motor speed, and 40mph is plenty of speed vehicle wise- adjust gearing/ voltage to match really.
Just saw his thread. The 1950/6 on 14 cells is a nice combo. My 100amp ESC got hot, but was fine. So did the batts, when I still had NiMH cells, now I use it on 4S (with a MM).
On 14 cells it's plenty fast, Serum can attest. Had it in my MBX5 once, with a 9920.
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