Generator mufflers

Has anyone had their generator muffler replaced with a better, more quiet, muffler? The factory installed genset has a straight inline muffler, and I was thinking about having a shop take a look at it see if they can come up with something better. I have plenty of space for something better,,,gregg

Brokeass Boater said:

Has anyone had their generator muffler replaced with a better, more quiet, muffler? The factory installed genset has a straight inline muffler, and I was thinking about having a shop take a look at it see if they can come up with something better. I have plenty of space for something better,,,gregg

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Many years ago on a Class C Tioga with a 4KW genset, I went to a muffler shop and had them add a Ford Falcon muffler inline with OEM, chosen strictly for size and the fact that it flowed probably 10 times the air as OEM so no concern with back pressure. Huge difference. Then I fashioned temporary, removable air baffles to deflect engine noise while being aware to not restrict cooling air, that made an even bigger differnce than the muffler. In the end the genset was quiet enough you couldn't hear it over others that were running three times further away.

Thedifference between a good genny and a bad genny is the muffler - buy a Honda or Yamaha muffler take it to a shop ( or friend) and weld it on . It can easily make a $500 champion genny purr,

Ps make friends with the Honda guy cause unless you know the right people its an expensive muffler

You didn't say what sort of genny you have so none of this may apply to you.....

I did...sort-of
Mine is an Onan, not very loud in the big scheme of things but it's an annoying sound in my opinion.

I installed an Onan optional part they call a resonator I believe.  I ordered it and was disappointed to find that it was an open flow through design.  I went ahead with it anyway.  The OEM muffler is inside the "box" with a tailpipe  coming out with two 90 degree turns to get it outboard.  I took the exhaust pipe to a local muffler shop and had them weld the resonator into place, and at the same time weld up an adapter bushing for a store bought Genturi pipe.

I don't remember specifics, regarding the empirical measured sound difference.  I'm sure I posted it and if I can get some time to find it I'll post a link to that thread...  but summing up as I remember it.
The dB levels as measured on my phone and not a "real" instrument were affected, but not by anything significant.
But the quality of the sound changed.  It sort of mellowed it out a bit, made it ...well a tiny bit more pleasant for the lack of a better word.  It wasn't a significant change.

Incidentally I say that the Genturi, when installed, has a similar affect, and it is accumulative.  Together it's really an almost negligible change but I'd say it is different.

Many folks will tell you that the mechanical noises are more significant than the exhaust noise.  That is likely true...but I would argue that if the exhaust noise was eliminated completely the result would be a significant improvement. 

Before I did this I considered finding an automotive muffler that would work.  I didn't look very hard but I didn't find anything.  Then after I had done this, I found a tractor muffler at a Tractor Supply store that was about the same size as the Onan resonator, but not an open flow through design like the Onan part is.  I'm fairly certain it would be better.

here's a couple photos of my install, and one of the muffler in Tractor Supply

edit:  one more thought I've had was maybe trying to wrap that whole pipe and resonator with header wrap.  i don't know what the real name would be.  I read a post by someone, I don't know where, but they had said they did it more for the heat issues, but did see some change in sound levels...  I'm guessing it would be a small affect too.

I found my old post with more info.

http://www.rvforum.net/SMF_forum/index.php/topic,88060.msg855485.html#msg855485

steveblonde said:

Thedifference between a good genny and a bad genny is the muffler - buy a Honda or Yamaha muffler take it to a shop ( or friend) and weld it on . It can easily make a $500 champion genny purr,

Ps make friends with the Honda guy cause unless you know the right people its an expensive muffler

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factory installed onboard Onan 2.5 propane,, with only 38 hrs on it,, not going to haul a second gasoline genset, plus the gas.

Onan 2.5 propane,,,We don't depend on the genset for the majority of our power, mostly for the microwave and coffee in the morning. I did use it this past weekend to run the a/c for a couple hours in the afternoon, that was a first because of the location of where we camped.  Looking at the set up, I think Onan has compactness and cheapest in their selection of exhaust components. I agree there is a secondary noise coming from mechanical sources. Thanks for the post link, I picked up a few ideas from those that have step on the same sticks ahead of me,,,gregg

Brokeass Boater said:

factory installed onboard Onan 2.5 propane,, with only 38 hrs on it,, not going to haul a second gasoline genset, plus the gas.

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I have the same generator on my Era. My DW hates the sound of it, so I was investigating options. Onan makes a resonator specifically designed for their generators. I bought one (only about $30-$35 if you search for it), but have not had it installed yet. However, I am able to fit it over the end of the exhaust pipe which should yield about the same exhaust sound level change. The result is disappointing. About all it does is soften the cracking sound of the exhaust when heard outside. Better for the neighbors, perhaps, but there was little detectable change inside the RV.

Has anybody tried the SuperTrapp mufflers? I hear they work really well, but don't know anybody personally that's used one. For as low as $100, it might be worth looking into.
https://supertrapp.com/shop-products/universal?p=2

I was curious about the onboard generators. I was looking to get one installed on my motorhome thinking that they were quieter than most external generators. This thread is making me 2nd guess it. I found a Kohler and an Onan at a local RV salvage yard. I am waiting to hear back on the price, but we are also considering a Honda EG2800 to just carry around. I have an old marine gas tank that I can use as an external fuel source so I don't have to keep filling it up.

Currently, I have an old Agtronic 4500w generator with a 10hp flathead briggs. I used 2 lawn tractor mufflers to quiet down the motor, but those flatheads have a LOT of mechanical noise and it is still super loud. That's why I am considering a different generator altogether.

when I was doing my project I did look at the supertrap (or something just like it anyway).  To spendy for me, not knowing what sort of result I'd get.