can't find any numbers on the website, but my 80 oz/in motors are capable of 120 rpm so I can't see yours being slower. Check that your screws are not binding at either end of travel, as that has in the past caused just buzzing with no turning. You'd have to turn 400rpm to get 20 ipm, right? Huh...don't know how that math works out then, cause Steve Manzer is getting 20ipm and I think he is useing the the same cheap motors. I'll do some reading on his site today, post later.