ZoomZoom-RCU

Anybody in here familiar with how to build a muffler for a Surestart. Any designs or ideas/suggestions? After watching this vid I know it's possible.

TIA ZZ.

http://www.youtube.com/watch?v=zrgbUFCzt_g

propjobbill

This is a post for making a throttle control, and it also works for a muffler. http://www.rcuniverse.com/forum/m_2874106/tm.htm I will take some pictures of mufflers I have made for sure start and post them a little latter. But the question is are you looking for something that looks like most other mufflers or for something easy and inexpensive to make?

KidEpoxy

I just went to the local Home Depot to grab 3 or 4" of tubing to help quiet a Wasp061,
and they no longer had the reels of hose/tube.
I refuse to by a 10' package of 5/16 or 3/8 tube just to use 4" of it
and have yet more leftover crap cluttering up my workarea.

Why do we have to spend $4 to get the 20cents of hose we need, +9.5' extra

propjobbill

Here is a picture of two different design mufflers I have made, both are cheap and easy to build. I am currently working on a couple of ideas I have seen here on RCU they include a round type muffler along with a sleeve for speed control. When I am finished I plan on posting results.

The square muffler is just that a muffler and works OK. the round muffler is made something like the throttle control listed above. I tested the rpm for the round muffler by restricting the exhaust, with an APC 7x3 Prop on 25% Sig fuel It is adjustable from 7800 = 12200 rpm

lildiesel

That two machine washer and exhaust extender tubing muffler/exhaust throttle idea was ingenious.

ZoomZoom-RCU

I like the one to the left in the first shot thats just a muffler, not a throttle as well(sorta looks like its made of metal tube or pipe similar to a larger glow type). Did you say cheap and easy.....why yes that does have a certain appeal as well. So do you have to be a machinist to produce one? Thanks by the way for all the helpful responses.

ZZ.

PS. So can the round one be used as just a muffler, without throttle control? And how heavy is it?

Thanks again!

lildiesel

The old Cox annular mufflers seemed to work best. They are basically an oversized collector ring with a 1/16th hole in the side. The QZ version of this with the spring steel slide over a large radius around the collector outlet was basically on/off for muffling after you opened it more than a crack.

Soon I'll post an OK Cub collector ring "muffler" [ha! ha!] I've been working on based on some OK original exhaust deflector parts. This is going to get a glow Cub .049 onto the flying field where I take my larger planes, by rule if not by db meter. The problem so far has been getting enough unburned castor and fuel out of the collector ring to keep it from bogging down on its own exhaust. Bigger exhaust stack holes are great for that, but there goes any muffling... right now I'm down to 3/16th ID with no discernable muffling or rpm loss. If I have to go down to 1/16th and start losing rpm I'll back up and put a small can muffler on the exhaust stub.

ZoomZoom-RCU

That looks neat too lildiesel. What are you using to connect the two halves of the muffler? I expect it has to be pretty heat resistant.

ZZ.

propjobbill

I have taken some pictures of materials used for making ring type mufflers. If you could find 9/16" washers that were thin say 25 thousands thick they would work best. I was unable to find washer like those in the link above where they were a throttle for Cox engines. I have learned you can use one snap ring at the top and one at the bottom with a 3/4" spacer washer top and bottom with a pipe spacer between for Wen-Mac engines to make a muffler.

I do use a drill press and a belt sander to make my mufflers. If you can't find thin washers you can make your own out of thin metal like valley tin. I drill a 9/16" hole in the middle of the piece of metal. In the case of Cos you will need to slightly over ream the center about 4=5 thousands so it fits snugly on the piston sleeve. Cut a piece of copper or aluminum tubing about 1/4' long. I use a pipe cutter to cut the tubing. Drill a 1/8" hole in the piece you cut off then you can push a piece of 1/8" copper, brass, or aluminum into the hole to make the exhaust port. I use JB Weld to cold the ring and washer in place.

You lay a washer over the sleeve drop the ring into place put on the second washer. I put JB Weld on the washers toward the ring. I then take a 1/2" snap ring slip it over the sleeve and push it down tight and let it dry. Once it has dried you can remove the assembly and glue it better from the inside to make it air tight. If you are going to make a throttle you need air tight or close.

It takes me the better part of 30 minutes to make one of these muffles plus epoxy drying time. Buying a Cox muffler is much easier and less time. But I know of no place you can buy new Cox muffler except some times on Ebay. I did buy a couple here on RCU a while back, but they are getting harder to find.

lildiesel

Just J-B Weld epoxy from the tubes applied with a toothpick to one side of the joint between the two exhaust deflector rings after they have been filed to size for top insert diameter and thickness. Then a thin coat around the outside when the exhaust stub has been fixed in the hole. It will look a lot better when filed and sanded clean and sprayed with hi-temp valve cover red.

ps: This works fine with diesel fuel. Not sure about prolonged exposure to 25% nitro, though.

lildiesel

fritzke

My Feedback: (1)

I'll see if I can scare up a batch of those Hillman "machine bushings" that fit so well.
Perhaps the clear vinyl tubing would work in place of the expensive blue silicone stuff I used a few years back.
I hear it may be getting hard to find as well???
I will also check the auto parts store for those grommity looking things, add an extension tube and Bobs your uncle.
Dave

ZoomZoom-RCU

Wow...lotsa cool ideas guys....guess I'll have to start gathering some components. : ) Thanks for all the info!

ZZ.