I have a YS 91 AC, installed in a BRAVADO F3A ([URL]www.acrobatico.com.br[URL]), that is with one weight of 4005 grams. Currently flying in Brasil. Already I tested some type of props. Between them APC 13x12(-----RPM), 14x10(8500RPM) and 14x8(9700RPM) and the flight of it was not good, summarizing, was very fast in level flight and with poor force during the ascents. To know of the reached friends whom this exactly motor also has the RPM's with these props and with others for example, APC 15x6, APC 15X8, APC 14x6, APC 13x11, APC 13x13, APC 13x14, APC 14x12, APC 14x10, APC 14x14, Thank´s so much for help.

P.S.: Always run with WildCat Fuel 20/20