Exhaust How to make a muffler that is super quiet / max stealth - pics

professor

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The first pic is to show this particular muffler that is in 2 sections. it is made out of a small electric motor weather enclosure. It does not have to be in two sections. This is what I had on hand. A used fire extingisher or any cylinderical light steel tube would be fine. In my case I had to fill a couple of small holes and adapt a tube to one end:

IMG_1498.jpg


The white you see is what makes this a lot quieter than a normal muff. It is fiberglas wrapped around a heavy wire screen. Any kind of fiberglas will do, even old window curtains made of the stuff.
Here is a pic of the insert:
IMG_1497.jpg



Each end tube has holes drilled around the part of the tube that goes in the muffler housing and the end capped:

IMG_1496.jpg

The drilled pipe could be one straight piece with a divider in the middle(maybe 2 dividers to separate the noise a bit rather than my offset style with 2 pipes.

This one is going on my 24 inch FS 6hp mountain bike. Just playing around and yelling into it- this thing is great.
Maybe I'll do a sound meter check at the rear of the bike later on.
 
Hi Fabian, the muff is mounted on my 6 horse (a work in process shown in the "Wild in the streets" section) and I gave it a shot of ether and some oil-pulled the rope and it sounds like a mellow, stock old 350 honda. Only gave a couple of power pulses. Not as quiet as I had hoped for (dead silence?), Waaay quiter than the goofy system toro had on the snowblower it came off of.
As soon as I get it done I will bring the sound meter home and check it.
 
nice

Good work.
Wonder if i could take my SBP expansion chamber and modify the muff.
 
As long as you place the muff on the end of the ex. chamber, you will be fine. This way it doesn't interfere with the reflected waves in the chamber.

An xtra note on exhaust in general-the longer the system - the quieter it becomes. More than one muffler= quieter yet.
I once ran a v-8 Ford with one glasspac in the middle and one on the end in the tailpipe. Though the whole system was straight thru, it was very quiet.
 
I really mean it would be nice to modify the existing muff.
Is it too small or is it possable.
 
Just remember to replace the fiberglass every 3 months or so, otherwise it will not muffle.


You would also drop a large amount of decibels, (and i mean a large amount) by modifying your exhaust to have an interior stinger, instead of an exterior stinger. just make sure you countersink it in past the beginning of the baffle cone, or youll lose power.
 
Maybe it's the material I use, but I have never needed to replace the fiberglas in the inserts I have made which I use in my dunebuggy. They get a good coating of black from the exhaust,but the material stays fine.
Good tip on the interior stinger.
 
the glass will never actually burn. Put real nice quality glass (even the cheap homedepot stuff is relatively burn proof) in a fire, the next day it will still be intact. The problem is that it gets clogged with 2 stroke soot and gunk. Once the cloth clogs up it no longer absorbs much sound.
 
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