[suicideneil]

Length and diameter both make a difference, since a fatter rotor has as much of an effect as a longer one, so to does the number of magnetic poles the rotor has; hence why a 4 pole 43mm x 74mm motor is nearly twice as powerful as a 36mm 2 pole motor the same length. It's impossible to give exact figures because there are far too many variables.

Kv rating & voltage you intend to use will make a big difference too- for 4s lipo a ~1800-2200kv motor is great, for 6s lipo more like ~1400-1600kv is ideal. For your needs, something like the 40x82 leopard motor would be fine baring in mind kv rating & voltage choices..