I have a Saito .72 in mine. I wanted a four stroke sound and an inverted engine as I didn't want to chop that beautiful cowl. The balance came out perfect on it. I have the battery mounted right at the back of the fuel tank and surprisingly everthing worked out great weight wise. The .72 moves it plenty fast, at least for me. Never clocked it but it seems faster then the WM T-34's which have been clocked (radar) at 90+ . Great looking, great flying plane well worth the money IMHO