Quote Originally Posted by daliad100
What do people think to lego power functions as drive motors?

According to here the Xl motors have 40 Ncm stall torque, 220 ish rpm (no load, 9V), draw 1.8A when stalled and weigh about 70g and the medium ones have 11 Ncm stall torque, turn at about 400rpm (no load, 9V), draw 0.9A stalled and weigh about 35g.

I think they are both under 2 in all dimensions and you can probably do something about mounting them using the holes or glue/solvent (pretty sure the majority of lego is made from abs.)

Ah, you should check out my videos!
www.youtube.com/ochayedonald

incidentally, with the rechargable batteries from Lego the heaviest weighs 805g-ish.
Thought I'm not sure an entire lego construction would stand up to metal constructions!