Volts/resistance of motor=Amps motor pulls
(Amps*Volts)/745.699872=Horsepower

So you need to measure the resistance of your motor via multimeter and the volts is the voltage of your pack.

So to simplify the equation
((Volts/Resistance)Volts)/745.699872=Horsepower
Then the total hp of the full system (2 motors) should be somewhere around 2x the hp of one. I say somewhere around because the esc has its own resistance adding to the confusion to me...