What engine would you all consider is the most versatile? That is, it can be used in diferent type sizes/style planes?

Of course everyone has a 2 cycle 46 in the hangar, but what else are you finding is a super versatile engine that will fit in a lot of stuff? Maybe a 90 size 4 stroke? I see those go in just about anything including 40 sized 3d'ers.

I am looking for a 4th plane (looking at possibly a sig bipe) and already have 2 46 2 strokes and a 40 2 stroke and was wanting to broaden my engine collection. Wanting something that can be versatile for various planes.

Of course this is all personal preference, but I would have to say that a .90 size 4 stroke is a very versatile engine. There are a ton of airframes for it so you can be flying something new all the time! Also that size engine gets you into a larger sized plane and as you know, bigger planes fly better than small planes. If I was told that I could only buy 1 engine for the next 5 years of flying excluding gassers, it would be a 90 sized 4 stroke. BTW, I have an Enya .90 on my Sig Astro Hog and it flys it great. It should do a fine job on a Hog bipe.

I'd have to agree with the next most versatile being a 91 four stroke. (The first being a 46 two stroke.)

But be aware, once you buy and run a four stroke, you may never want to run a two stroke again!
Dennis-

It all depends on you priorities. I consider my .45 4 stroke to be very versitle. I just put it on a .25 low wing plane. A while ago I used it on a plane with floats. Can also mount on a bunch of different high wing planes such as a Piper Cub, etc. I think it's a great size. I also consider a .25 2 stroke to be very versitile. If I put it in a quick .15 size plane, I have a little rocket. Mounted on a standard .25 size, can run all day on little fuel. In case you haven't noticed, I like small planes. I've got two in flying condition right now. I can put them both in the back of my truck, with the wing on. Needs no assembly or disassembly at the field. Others prefer larger, or smaller, engines. If I built a rack for the truck I could probably get 4 or 5 .25 size planes in there.

What about a 70 sized 4 stroke? Is there a pretty wide range of uses for one, or would you all stick with the 90 4 stroke?

I would say a 90 size four stroke. If I could only fund one engine I would buy a Saito 100. It would fly a 40 or 90 size Funtana, Ultra Stick 60, any number of warbirds,scale aerobatic (extra 300, Edge 540 etc. and many sport models like a 4 star 60. These size models fly good but are still easy to transport to the flying site.