I am unfamiliar with the notion of an 'air watt'. But wikipedia tells me that it is the mechanical power developed by the motor (not the electrical power).
Regrettably that alone is not sufficient to predict the pressure differential that such a motor might create. One can imagine a terribly wide throat, a large flux of air, and for a given 'air wattage' you would have very small pressure drop.
Equally, if one were to constrict that throat, the mass flow of air would be reduced, and the pressure drop would be large.
I think that we need to know the pumping rate (kg/s) of the motor.