Engine is an OS .46. I noticed when flying that there isn't much difference between 1/2 throttle and full throttle, but at full there is plenty of power to do most any non-3D manuever. I am not sure if the engine is performing up to snuff, however. It is 20 years old, but had only 10 hours or so of time on it when I took it out of my last glow plane. I took it apart and cleaned it, and am still fine-tuning it.