I had thought about placing a saito 5-cyl. in this one, but I have looked at the fitment, and found it to be tight...
The other issue would be the wing loading... and It would seem that if you can keep it light, I have a os 1.60 that would work well...

I don't see how I could get a plane down 4-lbs from what others were getting there planes at..
but who knows... I have not the time to work on mine....

My saito 5-cy will be going in the Topflite Fw-190 .....
IT will not be crazy power but I know that the saito 325 5-cyl engine did very well in aeroworks 50-60cc Stearman biplane and had plenty of power.

I would love to get the new saito 80cc gas radial that will be out in the near future....as it pulls around a H9 Carden yak54 like a 50 or 55cc gas single 2-stroke....

Here is some video of it running...

http://www.youtube.com/watch?v=lwCd7...ure=plpp_video