I only use 380Size black Big Motor(No Water Cooler because it is no space to input it)
And TP Mini ESC. Use 2 A123 (3.6V X 2) = 7.2V. ($100)
Mini Servo 9g ($35)
Flysky GTR3B 2.4 receiver.
First thing use Bushless Outer Runner to build, but the motor shell will damage inside the shark.
And think use the Bushless Inner Runner, but no low KV motor (e.g KV1000 380Size) to choose.
So just use 380Size black Big Motor, and near 6.8V A123 to build in, I think it will not very hot
but the speed will not fast.
I can't type chinese ya! Ching you use 11.1V to play the shark before?
Because if you use 11.1V to play the 380Size Motor, it will over the motor limit and will get very hot.
So now i use A123, fully charge it will go to 3.60V, but in play, it will drop to 3.40 one cell.
Only 3.40V X 2 = 6.8V. The motor will not hot but the speed not fast.