also, a 3 bladed prop sized to the equivilent 2 bladed prop will NOT have the same power. 3 blades are always going to be less efficient, both due to reynolds numbers but also the fact that more of your prop blast is now directly hitting the fuselage, causing increased drag. so in other words, only run 3 blades if you have a little extra power to spare. if you want the absolute most out of your engine, run 2.