Ive been playing with props. I want to try a 14X4w. I currently use 15% cool power. Its good cause I can use the same fuel for all my engines. I really dont want to get on the 30% heli but i have one gallon and will try it if it wont swing that prop on 15%. I just wanted to avoid buy two types of fuels and switching them out of my field box. Plus how much money that stuff cost. I have two 1.80s and both have plenty of power on 15%.