Can you post a picture, Frank? (Is it like the photo attached?)

I think you are talking about an early "flow thru" style muffler. "Open face" is generally meant to describe the engine stack with no muffler installed. If you look in rule books, there are events that require you to run open faced, meaning no tuned pipe, no mini-pipe, and no tuned mufflers. This limits performance when needed.

There is no question that the noise is coming out the front--even in flight. The speed of sound is waaaaay faster than any air coming in the front of your muffler! And looking at the geometry of the picture I found (which may not be the one you have) you practically have a megaphone on the front end.

If you decide to try modifying the muffler, just be careful of making it too restrictive and overheating the engine. I would think you could make it work.

MECOA lists a muffler for the Silver Star: part number 30-2101, but does not show a photo. It may be the same as you have, or it may be a later factory muffler. They appear to be sold out. But they might be out there to be found.

Even a hardwood plug in the front is good enough for a test. JB Weld would hold up for quite a while if you don't cut/sand/trim it. The skin formed during cure seems to provide the fuelproofing.

How big is the muffler exhaust dimension? You will probably have to close this down a bit also--perhaps down into the .350--.310 range once you cap the front.

A nice little project, but if it does not give good results, what other mufflers might fit? Does Randy Smith offer one, ready to go? I understand these engines were used for stunt, so I'm sure someone has found a muffler solution.

Good luck,

Dave

I've got a legacy aftermarket Kavan muffler for my Enya .35-V TV. It is venturi style but has slits formed by the larger nose to allow air in. For noise reduction, it came with a quarter (coin) sized milled circular plate that was inserted in the front of the muffler to blank off the slit opening where greater muffling was required. It's weight makes it only suitable for RC.

For yours, it would require closing off the venturi opening up front, but of course anything done might require modifying it, changing its exterior appearance (extra screws, etc.). I'd think one would be better off spending a little and buying a suitable tongue muffler for it.

Frank,

Have you tried blocking the muffler air inlet to see if the sound level is acceptable? If the noise level drops to something you can live with, then I would go ahead and modify it and see if you like the way it runs.

Here's a quick way to test it out. Cut two 1/8" plywood disks. One just bigger than the front of the muffler, and one that just barely fits inside. Glue together like a wedding cake. Hold it on by stretching an o-ring from behind the manifold over the front of the plug in the center. Glue on a couple of cleats to the front to keep the o-ring from rolling off. Tune and fly.

Admiral Spencer left a caution that there are internal baffles in this muffler. I couldn't tell that from the outside photos, so altering those may be part of the overall solution. I can't think of a baffle configuration that would require mods for it to work, but if the original muffler had so much back pressure that it actually had to "leak" out the front, then if you block the front, you have to improve flow to the rear.

Also, I am a bit lost regarding the configuration of the Enya and aftermarket mufflers that George discussed. I see no evidence in the photo of air slits or even blocked air inlets. A bit more info would help...?

If you don't want the weight of the stock (or modified) muffler, then a tongue muffler or a Dinger-style can muffler would be a good compromise. It's the All-American choice of farmers:  either fix it yourself for no coin, or pay somebody to fix it. Or buy a bag of earplugs and hand them out to anyone within a 1/4 mile....

Good luck!

Dave