Quiet Generator

[Phoebe3]

Originally Posted by Lindt

Phoebe3
Just saw your post. Did you install the Onan resonator or something else? Do you feel you had a significant noise reduction? Did you measure dB before also? Onan claims only a 1 dB reduction but You Tube video I saw sounded like more.

I did not test before installing the resonator and I used a NIOSH app on my iPhone to perform the test so the readings might not be very accurate. To my ears, I'd say it cut the volume by about 20%. Additionally, the tone was lower so somewhat less irritating.

The resonator/muffler came from Amazon (Cummins Power Generation 155-2449). The cost was about $46 and we paid a welder to put it on so total came to less than $100. Negative Amazon reviews seem to stem from folks who used the slip-together technique rather than welding.

10 Feet away = Onan 65 db; Van engine 62 db

50 feet away = Onan 51 db; Van engine 48 db

Recorded 12/2017 after putting resonator on. Readings taken from passenger side. Onan exhausts from driver’s side but our neighbor's house is there so I couldn't get a reading.

We are considering adding another one or a baffle on the end of the generator tailpipe. Would be great if it was no louder than the van engine.

[Lindt]

Phoebe3
The resonator seems to be part of the solution. An Onan rep. I recently spoke with said much or most of the noise is mechanical from the engine thru the green housing. The sound insulation installed in the Crossfit seems to do a good job inside the van compared to others I've checked out, but proper sound insulation around the housing under the van seems unlikely. Others have beat they're heads against this wall. i wonder if some version of what's done at https://www.sounddeadenershowdown.com/ would work.

[Phoebe3]

The only reason I would run the Onan is to run the A/C, microwave, or blowdryer. EACH of those items is louder inside the Crossfit than the Onan. Therefore, my main concern was how it affected my campground neighbors and I only took exterior sound readings.

[Lindt]

Originally Posted by Phoebe3

The only reason I would run the Onan is to run the A/C, microwave, or blowdryer. EACH of those items is louder inside the Crossfit than the Onan. Therefore, my main concern was how it affected my campground neighbors and I only took exterior sound readings.

Understood re: inside noise. The noise thru the housing is also a contributor to outside noise - as much or more than the tailpipe per the Onan rep. I was just commenting that the sound insulation on the Crossfit works and if something could be put on the inside or outside surface of the generator housing it might also work. I realize that it is a much harsher environment than the inside of the van. These surfaces get hot and wet.
One, very expensive, Class B with an LP generator that I test drove was almost as bad as putting a pot over your head and hitting it with a spoon, yet otherwise was quiet on the road.

[Phoebe3]

I think one or two of the frequent posters on this forum have insulated their generator housing for noise-dampening purposes and I hope they will notice this thread because i can't remember who they are.

My thinking was that if I could make the Onan no louder then the van engine (on my budget), that I was doing as well as can be expected. We hardly use it. We ran it all night in a truck stop once because we couldn't get to a park with hookups, but mostly if it's so hot we can't sleep without AC, we'll go to an RV park.

[booster]

Mojoman was one of the folks that insulated for sound, but he did a ground up install in his home built. He claimed it was very quiet when done. If you look up his thread for his van build, he has all the details of the genny install IIRC.