Home made muffler help please

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Etpm
Posts: 4
Joined: Sat Mar 29, 2014 12:28 am

Home made muffler help please

Post by Etpm » Mon Mar 31, 2014 12:49 am

It appears that I will be able convert a small engine from air to liquid cooling. I've received good advice so far on that subject. I will also need a good muffler. After an admittedly cursory look on the web I have not found the info I need to build a compact muffler that significantly reduces the noise coming from a small engine. Anybody here done that type of thing? Or know of resource that will explain how to design and build one? I need one that is as compact and as light as possible. For a 4 stroke engine. I am trying to build a small engine power source that is very quiet and light the engines to be converted are a Ryobi and a Honda. Both engines are nominally 1 HP.
Thanks,
Eric

dly31
Posts: 1042
Joined: Sun Jun 27, 2004 11:29 pm
Location: Northeast Alabama

Re: Home made muffler help please

Post by dly31 » Tue Apr 01, 2014 8:49 pm

The only suggestion I have is to either make the muffler also water cooled or substantial enough to deaden the noise of the exhaust pulses coming through the sides of the muffler itself. With the same mufflers and exhaust system, I was amazed at how much louder under the hood exhaust headers were as compared to cast iron manifolds.
Don Young

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ronm
Posts: 765
Joined: Sun Jan 05, 2003 9:32 am
Location: Colorado

Re: Home made muffler help please

Post by ronm » Tue Apr 01, 2014 10:19 pm

You can buy a 1/2" pipe lawn mower muffler for less than 5 bucks...run it through 2 of them...

jpfalt
Posts: 982
Joined: Sun Jan 05, 2003 12:55 pm

Re: Home made muffler help please

Post by jpfalt » Sat Apr 05, 2014 7:48 am

I worked as a design engineer for Shindaiwa and worked with some quiet versions of mufflers.
The Shindaiwa engines are similar in size t the engines you are working with.
Typically the mufflers were roughly rectangular and laid flat against the side of the engine. Regular mufflers were typically all etal with a baffle plate that ran around the exhaust from the muffler. The quiet muffler had sheets of ceramic fiber material attached to the muffler wall directly opposite the engine exhaust port and had a divider plate about half way down the muffler with additional sheets of ceramic fiber mat. The divider plate had a few small holes to restrict the flow of exhaust between the upper and lower muffler chambers. The muffler exhaust exited from the bottom of the lower muffler chamber.

The design goal of the muffler appeared to be to put the exhaust through several expansions and contractions, put ceramic fiber so that the flow of exhaust through each restriction was directed at a ceramic fiber mat and to put the exhaust gas through as many 90 degree turns as possible.

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