There are probaly umpteen threads on this question, however maybe somone can give some advice. Many years ago I flew Profiles with side-mounted engines. For regular stunt and scale the engine was always inverted or in some cases upright. That's the way it was! 

Now as I am about to get back into CL I am building a Sig Clipped Wing Cub for Scale. It will have a side-mounted engine with head pointed outside. Already set in stone.

My big question is my resurrecting of one of my original stunt designs which had an inverted engine. I am thinking that a side mounted engine will be a better choice. It works fine on the Ringmaster so why not a full blown stunter. Why do I not see many of such? 

It's not as pretty.  If it has the typical engine bearer arrangement, then the engine mounting is integral with the fuselage.  This provides a lot of strength for the weight, which is prized in stunter construction.

Thanks much for the reply.  I thought that looks just may be the main reason.
The engine bearer is a good point, however so few airplanes use that anymore, I think I can do just as well with properly supported firewall mounting. While Stunters do use many high "G"s in the maneuvers both positive and negative, so do a lot of other models, especially Pylon Racers. When I did that, I broke a few wings, but never had a firewall come off.
Of course there are some of these RC ARFs that have engines come off the front, firewall and all. Too bad some of those guys know so little about stress and G loads, but they learn fast when the fingers and hand parts depart the body. 

WOW! WOW!  That side mounted engine is in one beautiful machine. Far too advanced workmanship for me. Thanks for showing it, Mr. Wescott.

The pic, came on great, but the Tank picture would not increase enough to read it.

 Oh sorry, I did not notice that.
 I don't know how to make it bigger but please give your Email adress, I'll send it over there. L

Well side mounting can give a better run with diesels (they also become easier to clear a flooded engine that way) and four strokes.

And it will also give more weight to the outboard side of the model and this in turn can reduce the amount of tip weight that is needed to be carried.

Also lends itself to inline designs very well - all inline means the thrust  line, wing chord and tail plane are all on the same line but it can look a bit plain and ordinary unless you have the finishing skills of Lauri! (Having the thrustline, wing and tail plane on different lines tends to be the more visually interesting in my opinion.)

The 'look' thing is very subjective, some modelers like the engine to be visible - some do not, some modelers like the horizontal lines broken up and to others it doesn't  matter but with all inline models you will need slightly longer landing legs as the thrust line will be lower than an inverted setup and that's the only negative I can think of really.

I do have a profile Cardinal that has a side mounted engine and it has the thrust line raised just like its full fuselage cousin and it does indeed look more appealing.

Cheers.

The trick to side mounting an engine in a built up fuselage is to use an RC engine mount mounted to a 1/4 inch firewall. This eliminates the hardwood engine bearers and gives you a tank compartment without obstructions. I have built 3 airplanes running Saito 56/62's this way and all 3 have worked out well, the last one was good enough to win Advanced at Brodak this year. For four strokes I like the two piece SIG mounts as they allow the carb to be positioned all the way back to the firewall.

The trick to side mounting an engine in a built up fuselage is to use an RC engine mount mounted to a 1/4 inch firewall. This eliminates the hardwood engine bearers and gives you a tank compartment without obstructions. I have built 3 airplanes running Saito 56/62's this way and all 3 have worked out well, the last one was good enough to win Advanced at Brodak this year. For four strokes I like the two piece SIG mounts as they allow the carb to be positioned all the way back to the firewall.

Another 'trick' is seen on the last side mounted version of the English Freebird, 1/2" square bearers set for 2º out thrust will taper them back hard against inboard side of the fuselage so its plenty strong.

This will leave 35 mm between the bearers for a tank and this should be large enough for most engines.