How Close
 

How close can a muffler be mounted to a cowl ring? I am installing a gas engine and as it sits right now I have a bout 1/8" clearance between the muffler and ring. It won't hit the ring but I am concerned with the ring being burnt due to the closeness of the muffler......any helpful ideas?????

RE: How Close
 

Sounds like you may be caught betwen a rock and a hard spot between centering the engine in the cowl and clearance for the muffler. Understand the quandry all too well. If you have the ability, it would be better to change to a muffler that would give you another 1/4 to 3/8 inch of clearance. Barring that, there would not be problem with what you have if constant moving airflow was maintained between the muffler and the cowl, but that will be a problem during run ups and such.

So you're down to two choices. Change mfflers or keep engine runs to the absolute minimum when the plane is standing still. You're pretty close, but unless it's a PVC cowl you should be barely ok.

RE: How Close
 

One other thing you might consider.......I have had the dame problem with a Spitfire, and I just inserted a small piece of "ASBESTOS," between the muffler and Cowl. Never a problem

RE: How Close
 

I can move the engine out if needed but I need to know the minimum clearance.....3/8", 1/2"? I haven't connected a fuel line or smoke line or set the throttle linkage so adjusting is an option...I have already changed from a rear pitts style muffler to a side muffler due to clearance so I have no other options....

RE: How Close
 

Buteos: Every installation creates own problems. There are a lot of variables such as, how restrictive the muffler is that you are using, how much escape do you have for the exist flow. those things have a bearing how much temperature you'll have. In my case, my muffler touching the cowl loosely, but I had no problems. I wish there was a simple answer but there isn't. Good luck with your dilemma.

RE: How Close
 

Buteos: Every installation creates own problems. There are a lot of variables such as, how restrictive the muffler is that you are using, how much escape do you have for the exhaust flow. those things have a bearing how much temperature you'll have. In my case, my muffler touching the cowl loosely, but I had no problems. I wish there was a simple answer but there isn't. Good luck with your dilemma.

RE: How Close
 

Buteos: Every installation creates own problems. There are a lot of variables such as, how restrictive the muffler is that you are using, how much escape do you have for the exhaust flow. those things have a bearing how much temperature you'll have. In my case, my muffler was touching the cowl very loosely, but I had no problems. I wish there was a simple answer but there isn't. Good luck with your dilemma.

RE: How Close
 

This muffler is mounted on a 3.2 which is installed on a Kangke Waco.....

RE: How Close
 

I have a 2.4 on my Kangke, Waco. I have the straight down muffler with about a 1/4" clearance. I've had no problems after six 10 minute flights. Click on the bottom of this post, on "MY MODELS," for a picture of my WACO.

RE: How Close
 

What you seem to be looking for is an absolute, hard, empirical, perfect, minimum tolerance type of number to go by. Sorry to tell ya, but there just ain't none like that to be had. Hobby, not rocket science.

In this hobby, quite a bit of it is trial and error, done from prior experience with a similar product/installation, or just "looks right." Basically you either change mufflers and use something that lets you feel comfortable, move the current engine/muffler combination, or become one of us ol' time pioneer hobbyists and give it all a shot to see how it works out. You never know what you can do until you try.

RE: How Close
 

HERE HERE

RE: How Close
 

No, I came here to seek the wisdom of the Elders with their infinite knowledge. Since wood is a combustable material it will burn if left exposed to high heat for a long enough time. If the muffler is 1/2" from the ring and 3/4" from the firewall and there is air circulation I can see no reason for having a problem. I'm not asking for a definate answer, just some help.

RE: How Close
 

You're probably good where you're at, but a taste more would be better. If you have an eighth, see if you can get another and run with it.;)

As far as the wood is concerned, if you paint all of the exposed wood flat black you'll never be able to see when it starts to charcoal.[8D] Out of sight, out of mind as they say.[X(]

I'm sorry, I couldn't resist that:) 3/16 to 1/4 should be fine.

RE: How Close
 

Would it help to add some aluminum tape to the area closest to the point where the heat would be, to reflect some of it????

RE: How Close
 

I agree with silversurfer. Besides..........If it catches on fire, what a glorious crash it will make.

RE: How Close
 

"3/16 to 1/4 should be fine"....thank you silversurfer, it took a while but I finally got an answer.

RE: How Close
 

I have a muffler nearly touching the fire wall on my yak. so I put a pice of "heat tape" between the muffler and firewall. A pice of a plumbers fire blancket will work also.

RE: How Close
 

I wouldn't be as concerned in it was the firewall but its the cowl ring which is thinner material. I order 1" stand-offs which should give me between 1/2" and 5/8" clearance.