Errrrr....

Joelansing, I think you fall under the old school of flight where we stuck the biggest motor that would fit in there and thought it made performance better. And in this case the weight of a .60 is not an issue nor is the weight of a .90 sized motor.

However, just to set the record straight a 3D bird needs plenty of umph but you also have to worry about wing loading. Also B.H.P can be a very deceiving thing. For 3D flight you need vert. pull power. Generally static thrust is a better indicator than B.H.P. For a 3D plane you want the motor to be at the min. of 1 1/2 times the amount of static thrust in compairison to the planes overall weight. When looking at the stats on paper (B.H.P for the most part) the 2 stroke motor will seem like the obvious choice. However, many times the 4 stroke of the same engine class (.46 2 stroke, .72 4 stroke) is better for 3D do to the ability to sling a larger prop without reducing RPM's, this gives the 4 stroke the advantage of more vert. pull power as well as the ability to throw more air over the control surfaces for 3D flight.