The power from the pump, the hydraulic motor, the snowblower and the driving motor/engine must all be the same (taking into account their respective efficiencies). Power is conserve throughout the system.
Equations and calculators available http://www.surpluscenter.com/Hydraulic.htm" .
Torque needed by the 16 hp snowblower @ 1000 rpm is 1008 in.lb (Power = Torque X RPM / 63025).
Assuming 0.85 efficiency, the characteristics of the motor are (you need to know the operating pressure or the GPM):
GPM = Torque X RPM / PSI X 2 X pi / 231 / 0.85
GPM and PSI will be the same for the pump. Power and torque for the pump are (assuming 0.85 efficiency):
Power = PSI X GPM / 1714 / 0.85 --> according to the website: «HP is for electric motors, double this for gas engines.» Multiply by 746 to convert into Watt (electric motor).
Torque (ft.lb) = 5252 X Power / RPM
Displacement of the pump and motor (with their respective RPM):
Displacement (in³/rev) = GPM X 231 / RPM