hi guys i hope u can help me out.. mouted the engine mout and the engine(w/o muffler at 1st) 90 deg later to find out.. the muffle wont fit coz the fire wall is too long.. i would have to shift to engine mount to the left to sucessfully fit the the whoel package. my last option is to mount it inverted..

can you sand the firewall down a bit??
If you do need to turn the engine, a little bit wont do much,
just some rudder trimming, if you must move it alot, DONT!

How much space do you need. I would recommend fitting some plywood spacers behind the engine mount before I would change the thrustline.

Duke

Best to do what Dukester says.

If you shift the engine left, even though it is pointed dead ahead (thrust line parallel to the AC long axis), it will effectively introduce right thrust. This may, or may not be good, depending upon whether or not the model needs (or will tolerate) right thrust.

Moving the engine vertically will have very little effect, in fact no noticeable effect at all on most models.

Moveing the engine to the side on most models won't make much difference, but might cause some odd rudder trim issues. Some models will be affected more than others though. On a tail dragger that is prone to ground looping (like a cub), it could make take off and landing really exciting. It will look funny, and will get "attention" at the field if you fly with other guys though.

Personally though, I wouldn't move the engine side-to-side, I'd do something else.

You could go buy a pitts-style muffler, which is meant for this kind of thing.

You could get an exhaust extension. This is a bit of metal that fits between the stock muffler and the engine to move the muffler farther from the engine specifically to handle this kind of problem.

You could also cut clearance in the firewall, and make the necessary structure changes to seal up that area. That depends a lot on how the plane is built and how much trouble you want to go through.

I don't think you'll notice any difference if you mount it a little to the left. Most planes can stand a little right thrust anyway.

30 years ago, when engines were much less powerful, many airplanes came with right and down thrust. Then, with smaller props and higher rpms, everyone gravitated to 0-0 set-ups. Now, you are seeing right thrust again, in particular in 3D planes.

You didn't say what engine you were using, but if it matches a popular OS engine in muffler mounts, they have muffler extensions for the .46, .61 & .91 that I have used. They may have them for the smaller sizes. Go to Tower and search for them.

hmm.. looks like i have no other choice but to mount it inverted. i am using a TT46pro on it.. got really messy with the cowling job... haizzz. and guys thanks a lot for u help .. i realy appreciate it.