Henke Torphammar

You really should go brushless and li-po. atleast brushless! (there are good nimhs these days too)

the avarage motor handles 3-4 times its weight(grams) in watts. so you are looking for a ~100gram motor that handles 400watts, better safe then sorry. there are the AXI 2814/12. It will swing a 10x6 @ 30amps on 10cells or 3li-po. (don´t want to go 12cells as BEC works best up to 10 [:-] )

You could also use one of the cheap sp400 sized brushless inrunners and fit a gearbox 3:1 or 4:1 to swing a 13x7 prop or so.