[RC-Monster Mike]

There would be no way of me knowing what you put the motor through. If you bought the 10L and it failed, I would replace it, unless there were obvious signs of abuse. The motors can handle the rpms. The bearings are the main reason for the rpm limitation. And yes, as the cells go down, so does the potetntial runtime. 18 3800 cells would give a very nice runtime and the power would be pretty insane. If it were me, I would dial the power out on the radio to make it more driveable (It will be a brute!).