have a look at car fan motors. any type. also car heater motors are good but they usually have a thin shaft.

your bound to get at least a 240w at 12v motor and ive seen a 1hp at 12v motor. they have serious power and they often come with a flat plate straight out of the armature with a mounting point for 3x m6s.

they are also real durable. that should do the job for you