Adding muffler to generator

[Rainier70]

I thought this was an interesting and inexpensive approach to quieting a noisy generator. Welding an adapter to the spark arrestor and adding a small car muffler.

http://www.alpharubicon.com/altenergy/gensetquiet.htm

[KennethW]

How would it work with HF 800 watt generator.
http://www.harborfreight.com/900-peak80 ... 60338.html
Or would the back pressure on the 2 cycle kill the engine.

[jgrote]

It actually works very well. The back pressure is no problem because the car muffler is designed to allow much more gas through it than your HF genny will put out. I have tried this, and experimented with different mufflers just to see how quiet I could get an old 5hp genny. I found that a muffler from a Honda Civic or a Toyota Corolla worked best. (I chose these cars because they are nearly silent when idling, so I figured I'd get the same result) I also did it to my riding lawnmower. Give a hillbilly a welder and you never know what he'll do. P.S. I found out of my lawnmower that replacing the stock muffler with a larger one did not make that much difference. I put the stock one back on and welded my modification to the "tailpipe" of that muffler.

[Rainier70]

I am glad someone had tried this, because I have no clue how well it would work. I just saw the article and thought it might help someone out.

[Shadow Catcher]

The exhaust is only part of the equation, the cylinder/engine banging away is a large percentage of the sound. My question would be what is the % db drop?

[MtnDon]

Yes, I added a muffler to a generator once. It did silence the exhaust. The quietened exhaust revealed the loud mechanical noises I never heard before. It was quite unnerving; sounded like it was beating itself to death. I did take db readings. I don't recall the exact numbers but the added muffler did get the noise down to where it could pass the National park test. Still not as quiet as a 'quiet model' Honda or Yamaha.

[M C Toyer]

The exhaust is only part of the equation, the cylinder/engine banging away is a large percentage of the sound. My question would be what is the % db drop?

I bought a 1400/1800 W Champion and built a box from 1-1/2" foil faced polyurethane then covered with aluminum sheeting. The box also provides weather protection as the whole setup is mounted to my trailer tongue.

The gen sits on a piece of 1/2" foam rubber floor mat over plywood framed underneath with 2x2 and insulated in between. Another 1/2" foam rubber mat is between the box and trailer frame.

I put an air intake on one side and cooling outlet on the other using standard register vents. I have a 12V radiator fan mounted in front of the outlet. I also made a 4" double wall opening for the muffler exhaust and once the cover is on can screw on a stock cylindrical muffler from an 18HP Briggs and Stratton to the spark arrestor on the gen muffler. I added an external kill switch to stop the engine without having to unscrew a hot muffler.

With just the box I estimate a reduction of about 20-30% and the muffler another 10-20% so overall 1/3 to 1/2.

I'm satisfied with the effort and the cost was minimal. There is a small vibration detectable by the metal breadbox that sits on top of my refrigerator with magnets so may change that to Velcro.

[working on it]

There's an upward pointing exhaust pipe attachment, designed for use on motor homes with generators, to direct sound and exhaust fumes up and away from adjacent campers. I think they require them in the infields at major racing events. And, to quiet the sound of the engine itself, some use "sound blankets" set up surrounding the generator. Both cost more than I'm willing to spend. I made an upward pointing exhaust for one of my generators, but it sounded more like a Ford Mustang exhaust than I liked (GM all the way), so I scrapped it. I made a "sound blanket" to cover my TTT generator, of the Ultratouch insulation (blue denim mulched insulation with Mylar facing), and it worked ok, but I never made a good mounting for it. Now that I will have to use the truck to haul the TTT, I may copy MC Toyer's design, and make a collapsible hard-sided sound cover, and transport it in the truck bed.

[M C Toyer]

. I made a "sound blanket" to cover my TTT generator, of the Ultratouch insulation (blue denim mulched insulation with Mylar facing), and it worked ok, but I never made a good mounting for it.

Ironic, or serendipity, I was just thinking of using some sort of sound blanket to supplement. Don't know if thick enough to do any good but I've got some old moving pads I could cut up and wrap around the outside of the box.

I also considered using flexible exhaust pipe and placing a motorcycle or small car muffler below the tongue, but as others have noted the mechanical sound is louder than the exhaust and the small muffler I have now is doing a pretty good job.

I'll post some pics of the box tomorrow. Was pretty simple but I had some space limitations. It is mounted at the very front of the tongue leaving just enough space to turn the jack crank and had to fit within the frame rails so as not to interfere with the weight distribution hitch mechanism.

I have a fairly long tongue and already have a box at the back but was saving the space in between for my bike or maybe a small dual-sport cycle.

[d120]

just remember the moving blankets(pads) are flammable

[Corwin C]

A friend of mine takes a full size generator when he goes camping. He places a special made box of 1.5" foam board over/around it. It has a box fan on one end to provide cooling/combustion air to the generator. The air has to turn several curves to get in, and several more to get out. Most of the time the fan seems louder than the generator. The major drawback is that it is BIG.

[Junkboy999]

If you check YouTube there a lot of mufflers and boxes home made to try to quiet down a generator.

[M C Toyer]

Insulated generator box on tongue showing cooling outlet:



Cooling inlet and muffler extension at back:



Cooling exhaust fan:



Interior of box. I left the foil facing on to protect the polyurethane but may remove in places for better sound-proofing.



The faux stone behind the generator box is for tool storage and at the top covers the air conditioner. It is made to resemble a chimney and has an extension (not shown) that sits on the roof with magnets and hides my TV antennae:



The space between the chimney and generator box is for firewood and/or my bike or mc. I moved the bike/mc mount back to install the generator box.

Re the insulating blankets, if used would be placed over the box with cutouts for the air vents and muffler.

[dratkinson]

Random generator thoughts acquired as I've wired my house to use a portable generator as a manually connected/switched backup. In hindsight wish I'd bitten the bullet ($) and installed an automatic whole-house solution.



Adding a better muffler to a B&S generator doesn't do much except reveal the other internal noises that the exhaust noise was hiding---it's still loud. Ditto what others have said.

Flexible exhaust pipe is not gas-tight. If you need gas-tight, you must use the bellows-type of exhaust piping.

One brand of acoustical deadening material is made by Acoustiblok. Never got around to trying their material as it was where I stopped looking when I decided to switch to a quieter generator.
http://www.acoustiblok.com/

The little HF800 generator is way louder than the little Honda. Easy to find YouTube videos demonstrating this. Don't think a bigger muffler would help it much. (I don't know. But it doesn't make sense to me that anyone would put a loud muffler on a quiet generator... so assume generator is not inherently quiet.)

You can buy pre-built generator enclosures, or retrofit an existing shed for generator use from No Outage. Or seeing what they offer, can give you some ideas to roll your own.
http://www.nooutage.com/portable_gen_ac ... ccessories

Bottom line. The easiest way to have a quieter generator, is to start with a quieter generator ($).

[Dave S]

Boy do I like this subject............One of my frequent camping events with a generator is at the NASCAR racing in PNix AZ. I bought a honda1000 and 2000 to use an "occasional" power and got the Honda because of NOISE......or lack of. While serious research indicated the Honda one of the quietest units in the market, I was still concerned about my neighbors. I stole an idea from the commercial RV units which deflect not only the noise, but the fumes upward. I capture the exhaust with something as simple as a funnel connected to PVC pipe. The funnel is connected to more PVC pipe to make a "t/y" unit with about 4" connected to the funnel (horizontal) and a 4-5" section with a footie on the bottom and about 4-6' of PVC pipe going skyward..............probably doesn't make sense, but it not only deflects my fumes upwards, but also quiets the already quiet Gen down a bunch. Further noise issues (the generator, not exhaust) are handled by pieces of insulation board and..........duct tape.........yah. Everything breaks down to a small bunch of piece easily stored........works for me, for about 25 bucks at Home Depot...............