a 24/10 for the gt80 . its a heavy engine that really lacks power for that size plane . for unlimited 3d a 100 110 is the tric pic for it . it will pull it out of a hover and that type of stuff . i power my planes on the extreme end of things so a little less that i think will be fine . i want to be able to flutter when i punch out of da hover those are a sweet flying plane i don't own one but have flown one waiting for the 50% when i find a big enough engine