I did some testing of my own with the motor, It seems that my results are consistent with yours. I was hoping we can get more power from this motor. I have a Hengli W3542 KV850 motor, which is virtually of the same weight and dimensions, to compare. I am surprised the Sunnysky KV920 doesn’t draw more power with the same prop. (Once again, it looks like you cannot totally trust KV values)
I’ve got a few thoughts out of my testing: The 13×6.5 prop + 3S + Sunnysky 2820 KV920 set up is very safe. The amp draw peaks at 40A or so. Using a 44A ESC, or even a 40A one, with this set-up should be adequate. The motor doesn’t get hot at all. I got 1.2 to 1.3 kg static thrust with about 20A current draw, which means you can hover your little edge at about half throttle. At full throttle, you can get around 2kg static thrust.
I think this motor has more potential. The manufacturer says the motor uses high-quality Japanese magnets, which can stand temperature up to 180 degress Celcius. I am going to get some KV1100 Sunnysky 2820 motors for testing.