If we increase turns
Idle current and HP will decrease in proportions to the square of the change in turns. Locked rotor current and starting torque will decrease in direct proportion to the change in turns.
If we decrease turns
Idle current and HP will increase in proportion to the square of the change in turns, Locked rotor current and starting torque will also increase in direct proportion to the change in turns.
Decreasing in turns leads to core saturation. For example, a 5hp motor, and that core (rotor and stator), are not going to do well if you try to make it a 10hp motor.
We can’t decrease turns much unless you want to make a hot motor with say a 10-minute duty cycle (10 minutes per hour).
If we have capacity margin in motor
If you had a motor made before 1950 you could probably increase the HP by 25% because they had large frames, low flux density, and low design temperature.
Your starting and accelerating torque will drop a little unless you change the start winding too.
