I'm looking at starting to fly pattern planes. Not for competition but just to see if I like. Anyway, I picked up a new in the box 90 size ( I think it's 90 size. It's got a 66" wing span) and I have a Saito 91 to put on it and plan to route the exhaust out through the bottom tunnel area. Will a 91 work on a plane of this size or is it too much engine? What type prop should I get for it? Thanks

Saito 125 would be better for the verticals.

Will the 91 work though?

What plane is it?

I don't know what plane it is. The box doesn't have any markings and there's no manual. I think it's basically a type that you'd find on ebay. Not a great one I'm sure. But one that I can get started with and see if I even like flying pattern and then I would like to move up to an Excelleron 90.

Without knowing some specifics, (such as weight etc) it is hard to guess for sure. With the 66" Wing span the 91 should fly it OK. It certainly won't be "too much" engine (I don't know if that's possible anyway) It won't be overpowered but as a practice plane to get started it ought to do the basic sequences just fine. As rl56 mentioned a larger engine would be better.

For the prop a 14 x 6 Zinger or APC is a good starting point.

If I was buying a new engine for that size of pattern plane today, I would look at either a YS 110 or Saito 1.25 (With the YS being my preference in such a model).

The trick to enjoying pattern is to just start flying it, preferably with another interested party calling for you and assisting. The feeling when you look back after a gallon or 2 of fuel and realise that you are starting to fly with more accuracyis great - It sure helps when sport flying too. We've all started at the beginning of this sport and we all aspire to be better, I'm sure. I try to practice at least some of my pattern routines to some degree with every flight that I do, regardless of the plane that I am flying.

Thanks aussiesteve, That really shines some light on what I'm needing to think about. Great information. Thanks. I do have a Saito 125 in another plane that I can use down the road if pattern flying is interesting to me.
There isn't any pattern flying contests in the area and only one guy that I know that flies pattern so I probably won't be able to get anyone to call for me. I'll weigh the plane parts and find out what I'm looking at for total weight. Thanks again.

Can you manage some sort of a picture?
Somebody might recognise what your plane is.

I'll have to wait untill Thursday when I pick it up from my friend.