I've flown two different Phoenix Models SeaBee .46 Sport/Pattern ARFs. The first I flew had an O.S. Max .46 FXi 2-stroke in it and it flew great with that engine. The second one I flew had a Magnum XL .52 RFS in it. The Magnum 4-stroke was turning an MA K-Series 12x6 prop at 10,000 RPMs and it flew just as fast as the .46 FXi turning an 11x6/11x7 APC prop.

Based on this experience, I am comfortable using a .52/.54/.56 4-stroke in place of a .46 2-stroke. When tuned and propped correctly, they're just as powerful for sport applications.

Four Stroke shoppers would do well to consider also the Thunder Tiger F-54s, F-75s, and F-91s. The F-54s is a solid value at $179.99, but with the F-75s selling around $169.99 to $174.99 at many TT dealers, it's not surprising most shoppers are opting for more displacement. Both of these engines are very similar in weight to other four strokes of the same displacement, only the TT F-91s is noticably heavier than offerings from other manufacturers.