I have four 4 stroke engines and I love them all. I have a Saito 91s that is my strongest engine, OS 70 Surpass and 2 Magnums (70 & 91) My OS and Magnum engines are on par with each other. I have posted a video here of my Magnum 91s four stroke flying my 1/5 scale SE-5a that weighs in at 10.5 lbs. The plane flys very scale like and everyone at the field connect believe my Magnum has the power to fly this plane. But seeing is believing. I have a APC 14x6 prop on it and I run it rich using Omega 15% fuel.
If I had all of the money I needed for this sport I would be using Saito and YS engines only. But I have to work for a living and the best engine for the Money is the Magnum 4 strokes, bar none.
Enjoy the video.
http://media.putfile.com/Jim-Flying