!! a Saito .91 on a SE !!

Well, let's see.

With the stock landing gear you'll be lucky to use props over 11". 12" can be managed if you make *very* short takeoffs and only three-point landings. Yuo will break a lot of props, though.

You'll have to use a steeply-pitched prop in order to load the engine properly. I run a Saito .91 on my WM Mustang, and have had great luck with an APC 11x12 prop.

It will be difficult to balance, but not impossible. I've read reports here from people that have used OS .70 four-strokes on these - the big Saito only weighs 2 oz more.

OK!
Now that I've said the above...

Don't do it!

If you put that Saito onto your SE it will have the flying characteristics of the Space Shuttle. Great vertical performance... very fast... not terribly forgiving on landings...

This plane is meant to be kept light! A good .46 is sufficient, if propped correctly (for thrust, not speed.) This plane works really well with big diameter low-pitched props - try an 11x5. If you replace the stock shorty gear with the taller one sold by TNT you'll have plenty of clearance for up to 13" props - at this point you can try a 12x4 or 12x5. You can also use a tuned muffler to bump the performance up a bit.

FYI - I have a YS .53 4C on my SE and the previously-mentioned taller landing gear. This engine weighs about the same as a .46 2C but swings 12x6 and 13x5 props with authority. This is a Wonderful combination - lots of power with low wingloading. Its like a butterfly