2.4 or 2.6,either is too heavy for this plane.This plane is not as large as other 1.20 size planes.The H-9 Cap or Edge dwarfs this plane.While it is an awesome flying plane,it will be too heavy for good 3D with the gas engine.I had one with a Brison 2.4 and it flew great but would not 3D well at all.If all you want to do is spins,snaps,etc.it will be fine,but if you want really good 3D,it will suffer,hover will be OK at best,but the other stuff,elevators,harriers,,etc.will not be there.The OS 1.60 is a much better engine for this plane.I know you want Gas,but this is not the plane for it.I used to argue with all the guys who said that the 1.20 planes were too small for gas,but I did it anyway,and was convienced it was me why they wouldn't 3D,it wasn't until I finally flew a H-9 Edge with a 1.60 that finally convienced me.There will probally be plenty of guys who will reply and say that I am crazy,that their planes do fine with gas,but I bet they consider a 15 second vertical position a hover!I don't mean to be cocky,but I've been there,on both sides,trust me.
Mike.