I have a single speed on a stock chassis and want to run the 9920 with a 8xl on 5s. I tinkerd with the "motor selector" and "Random Parameter Solver" and found that an 8xl with 5s and 18/54 gearing is "good" for a for a top speed of +/- 40mph, 20/54 for 45mph and 22/54 for 50mph without any overheating warnings.
Does this sound about right to you guys?