Advice finetuning generator exhaust noise

[wildwest2]

I own a Onan Microquiet 4000 which I am extremely happy with. I have it roof mounted in a custom soundproof enclosure and for a generator it's size, I'm pretty sure this is the quietest unit I've ever "not" heard. The only noise that can be heard from more than 20 feet is the popping noise and general exhaust coming from the stock muffler and tailpipe. Now, I understand this is totally acceptable by most standards, but being that I'm some sort of anal retentive perfectionist (and an engineer by trade), I would like to find a way to reduce this tailpipe noise so that the final product is the same coming out of the back end of most any automobile. So here's my question: Seeing as I have enough room on my roof-rack to mount anything I like, is there any reason that adding a new automobile muffler off the tail end of the generator's exhaust pipe wouldn't eliminate this noise? I had two thoughts. One, simply fabricate an adapter so that the auto muffler would bolt to the end of the tailpipe or, weld a 16" section of 1-3/8" perf pipe to the end of the Generator's 1 3/8 tailpipe to break up the popping percussion and then mount the auto muffler over the perf pipe so that the perf pipe fits inside the muffler, sealed behind it. If anybody has had any experience with this, I'd sure love to hear your thoughts and/or ideas! Thanks.

[MegaJohn]

lawtonglenn wrote:

mikestock wrote:

Happy Prospector wrote:
The best way to quiet this machine is to install solar and hit the off switch.

Great Idea. How many solar panels and batteries would it take to keep a 15k air conditioner running around the clock?

You guys crack me up... too funny!

Happy Camping!
John.

[wearenh]

mikestock wrote:

Happy Prospector wrote:
The best way to quiet this machine is to install solar and hit the off switch.

Great Idea. How many solar panels and batteries would it take to keep a 15k air conditioner running around the clock?

[mikestock]

Happy Prospector wrote:
The best way to quiet this machine is to install solar and hit the off switch.

Great Idea. How many solar panels and batteries would it take to keep a 15k air conditioner running around the clock?

[christopherglen]

You could have the exhaust dump into a vented box, with the inside lined with high temp sound absorbing material.
On an air compressor I found most of the noise was the intake, putting a pipe on it with large and small diameter sections tended to smooth out the popping. Similar idea to a resonator.

[Devocamper]

back pressure will damage the engine. being on the roof there is nothing to block the sound from travling in all directions . at least when it is on the ground or in a compartment the sound will travel but not everywhere. Why is your gen on your roof? You dont say the roof of what?

[Dakzuki]

If you have the room, go for it. An auto muffler will have minimal back pressure (due to it being massively oversized compared to a generator one) and you have the room.

or-

You mention your generator is up on the roof. Depending on where the exhaust exits you might just be able to put some small "walls" around it with sound deadening. The top can be open as nobody is above it. Pretty simple and you could mock it up before committing to the real thing.

[Happy_Prospecto]

The best way to quiet this machine is to install solar and hit the off switch.

[John_Wayne]

Had a friend put a motorcycle exhaust on his and I added a old VW tailpipe exhaust tip on mine.

[Chris_Bryant]

Onan makes an add on resonator for this purpose- there have been positive remarks about them here.

[jwicker]

Could pointing the trailing end of the exhaust pipe upwards help?