Ball bearing motor
(Update II: New video, we managed to make it run on a standard racing pack 7.2V (no clue to how many amps - but not enough to kill a large elephant, only enough to melt wires slowly))
(Update: A SlowMo edit of the video, especially for "mogul" - that's lack of intelligence for you, frame by frame :D)
A ball bearing motor needs a lot of amps.
We knew that.
We estimated that this one would do well with 10-15 amps.. But the LiPo battery I had around was a 6600 40C (Estimated 264 amps in the burst).. which turned steel into flying plasma.. a little faster than expected.
Note how close I am to severe burns - the table, floor etc got badly burnt - sometimes I am just lucky :)