This seems like a rather basic topic, but I could not find where it has been addressed on these forms.

Question:

When pumps are operated on electric motors, the motors never operate at synchronous speeds due to the principle inwhich they work. (Back EMF demands current draw to compensate for load).  Because this effect varies from different types of motors, don't manufacturers need to take into consideration the specific motor that will be used when manufacturers are trying to determine impeller trim?  If they do, are impellers trimmed based on full load motor speed, or on some interpolated speed based on motor load at either pump runout or operating point?

I hope this was clear.  Thanks for your time.

Due to the nature of electrical field interactions, assuming common number of poles, cycles, voltages ... , the net effect is that motors are more similar than different, resulting in the fact that there is probably no more than a 3% difference in motor speeds between full load and no load.  

You should use the speed shown on the reference pump curve.

 Are you going to eliminate 2 poles or something?