RE: Need.40-.50 Engine recommendations for 3D
The best combination of power and reliable transition will probably mean one of the following three:
OS, ThunderTiger, Webra.
The OS 46AX or 55AX are good motors but the Webra is also good and quite a bit lighter.
My choice however, is the TT46Pro fitted with a Tower/GMS47 muffler. This combo will give you gobs of power, superb transition and a very long-life.
But any of the three above won't disappoint.
Just steer clear of some of the Chinese 40-56 sized engines. They often make good power and idle fine but I've yet to find one that doesn't get a bit loaded up in its midrage -- which isn't so good for 3D.