that's very true about being back where you began with the power measurement.thanks for the link to the tach, and i found a link that might be helpful

http://www.simcotech.com/formulas/hp_electronic.htm

seems as though they have quite a few formulas, i'm not sure if this is redudant with micromo's website, but it could help. right now i am experiemnting with the 180 size motor and different winds, i'll keep you updated on how it goes