Hi All ... Ok, I have spent better than 30 years designing and bui;ding controlline stunt airplanes. Now it is time to move up into the world of R/C. Recently I have seen some pretty impressive 4-stroke engines preform. Since my prior experience is with 2 strokes ... WHAT IS THE CONVERSION BETWEEN 2 AND 4 STROKE MOTORS?? That is to say .. .if I have a 35 - 40 - 50 or 60 size 2 stroke plane ... what size 4 stroke should I be looking to buy?

Also .. who is the "top dog" in four stroke engines ... Saito? OS? Magnum?