dangit. My MAP sensor won't show up till Thursday and I'm gonna be out of town till Sunday....not that it really makes a difference because I have no way of turning motor RPM into actual pressure

@
jamesm - I hope it's close-to-that-simple. I mean...it could be. It would just have to know how often to adjust the ESC.
Off topic, but Ruby looks weird as balls. Your code reminded me to make a proper object out of my motor. I usually code procedurally. I'm about 20 years behind programming-wise.