I made a loud generator less loud. $30 fix.

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[ARCHIVED THREAD] - I made a loud generator less loud. $30 fix.

Posted: 7/27/2010 9:17:21 AM EDT

A while back there was a thread about hooking up a car muffler to a loud generator to tone it down. I put it on the back burner as a rainy day project... About a month back we had a 24hr power outage, it was very easy to tell we were running off generator power by the noise level so I decided to fit it.

I took the "muffler" off of my Coleman 6k gen and took it to a muffler shop. I told the guy what I wanted and he welded a 1 7/8" pipe to the exhaust outlet of the muffler for $20. I went to the autoparts store and got a section of stainless 1 7/8" flexipipe and stainless clamps for $9. A friend gave me a stock muffler off his HD 1200 sportster to connect it to.

Results: It went from being really loud to being able to talk loudly over the sound, a fantastic improvement. Even better the noise was the same at idle as it was under load, I started my 2hp air compressor and it never got louder. I ran it under load for about 45min to test it out, no issues as I cold tell.

For reference: The exhaust directly out of the engine is about 3/4", the stock "Muffler" is just a spark arrestor, it has no packing material in it. The stock HD exhaust handles one 600cc cylinder, the same size as the gen but with a much higher compression and higher rpm.

Posted: 7/27/2010 9:22:03 AM EDT

[#1]

Very nice. Hey do you mind posting the muffler part number from the coleman 6K gen set?

Posted: 7/27/2010 9:42:52 AM EDT

[#2]

One small step for man, one giant leap for OPSEC!!!!

Well Done!

stasiman

Posted: 7/27/2010 10:26:29 AM EDT

[#3]

Quoted:
Very nice. Hey do you mind posting the muffler part number from the coleman 6K gen set?

Tractor Supply Company has a nice selection of mufflers intended for small tractors. I run one on my small diesel generator.

Posted: 7/27/2010 11:15:49 AM EDT

[#4]

Now clamp the muffler across the back of the frame and shorten the flex to fit. Now it is set to go without assembly.

A lot of the noise on these gennys is mechanical noise. That is a harder problem to fix.

Posted: 7/27/2010 12:23:50 PM EDT

[#5]

Quoted:
Now clamp the muffler across the back of the frame and shorten the flex to fit. Now it is set to go without assembly.

A lot of the noise on these gennys is mechanical noise. That is a harder problem to fix.

A doghouse around it (ensuring plenty of cooling air) will take a lot of that noise out. I once made one out of 1" blue foam insulating board duct taped together, it worked great.

Posted: 7/27/2010 12:44:36 PM EDT

[#6]

Quoted:

Quoted:
Now clamp the muffler across the back of the frame and shorten the flex to fit. Now it is set to go without assembly.

A lot of the noise on these gennys is mechanical noise. That is a harder problem to fix.

A doghouse around it (ensuring plenty of cooling air) will take a lot of that noise out. I once made one out of 1" blue foam insulating board duct taped together, it worked great.

I've always though a well insulated shed would not be a bad idea for keeping the noise down. It would also give you a place to store fuel as well. In bad times, the noise of a gennie will bring all kinds of unwanted attention!

stasiman

Posted: 7/27/2010 12:48:39 PM EDT

[#7]

Quoted:

Quoted:
Now clamp the muffler across the back of the frame and shorten the flex to fit. Now it is set to go without assembly.

A lot of the noise on these gennys is mechanical noise. That is a harder problem to fix.

A doghouse around it (ensuring plenty of cooling air) will take a lot of that noise out. I once made one out of 1" blue foam insulating board duct taped together, it worked great.

iirc, there was a thread a while back about building an enclosure to reduce the mechanical and exhaust noise of a genny. essentially a wood enclosure lined w/ some kind of foam about 6' tall seemed to be the ideal (although unsightly) fix. the heighth help to get the remaining noise directed above people's ears.

Posted: 7/27/2010 1:23:17 PM EDT

[#8]

I put a car muffler on my generator and it made no difference at all. It was loud as hell both ways. The muffler started to turn blue from heat so I put the original back on to avoid damage.

Posted: 7/27/2010 2:19:54 PM EDT

[#9]

Nice set up, need to do this to my gen set.

Posted: 7/27/2010 2:34:37 PM EDT

[#10]

nice riggin. May look at this for the gen I purchase from TSC.

Posted: 7/27/2010 3:03:06 PM EDT

[#11]

if you elbow out of the engine to the front of the gen you can clamp the muffler onto the upright rail on the genny - i use a hose clamp on my muffler so i can remove it when i put it back in the shed - but since i have it pointing towards the front of the genny it is not necessary to remove the muffler nor do you need something to hold the muffler up - any muffler shop can bend or cut you the right length to the front of your genny so you can tie it on to the genny upright.

Posted: 7/27/2010 7:22:13 PM EDT

[#12]

Quoted:
I put a car muffler on my generator and it made no difference at all. It was loud as hell both ways. The muffler started to turn blue from heat so I put the original back on to avoid damage.

Had the same experience. Don't know where I went wrong.

Posted: 7/27/2010 7:50:22 PM EDT

[#13]

Quoted:

Quoted:
I put a car muffler on my generator and it made no difference at all. It was loud as hell both ways. The muffler started to turn blue from heat so I put the original back on to avoid damage.

Had the same experience. Don't know where I went wrong.

some genny have more sound from the workings vs the exhaust

Posted: 7/28/2010 1:52:55 AM EDT

[#14]

I saw a threead one time where this guy did the same sort of modification to his coleman genny, but he used a car muffler. He claimed it was very quiet after that.

Posted: 7/28/2010 3:50:51 AM EDT

[#15]

If this is a reed valve engine I would be concerned that additional backpressure would lead to additional heat in the cylinder head and likely damage the valve. There is a reason that the stock exhaust is configured the way it is, and it is not because the manufacturer is oblivious to the noise it makes. At the very least I would read temperature at the exhaust port with and without the modification just for peace of mind. A loud genset that runs is better than a quiet one that doesn't.

Posted: 7/28/2010 3:56:07 AM EDT

[#16]

If I understand correctly, this is what you have:

Engine > Coleman 6K muffler > 1 7/8" pipe > 1 7/8 flex pipe > HD muffler

that makes two mufflers in series?

Posted: 7/28/2010 4:11:08 AM EDT

[#17]

You can get an amazing amount of sound attenuation from a berm or some evergreen bushes as well.

Posted: 7/28/2010 4:33:57 AM EDT

[#18]

Nice work

Quoted:
A friend gave me a stock muffler off his HD 1200 sportster to connect it to.

The stock HD exhaust handles one 600cc cylinder, the same size as the gen but with a much higher compression and higher rpm.

I kind of got a chuckle thinking of a HD muffler and making something quieter in the same sentance

Posted: 7/28/2010 4:39:02 AM EDT

[#19]

You can permently mount that in your basement and run 3/4"stock out the wall and up to the roof just dont for get a cap

Posted: 7/28/2010 4:41:02 AM EDT

[#20]

Quoted:
You can permently mount that in your basement and run 3/4"stock out the wall and up to the roof just dont for get a cap

That is a very dangerous idea. Please do not attempt. One crack in a pipe and you have a dead family.

Posted: 7/28/2010 4:50:06 AM EDT

[#21]

Quoted:

Quoted:

You can permently mount that in your basement and run 3/4"stock out the wall and up to the roof just dont for get a cap

That is a very dangerous idea. Please do not attempt. One crack in a pipe and you have a dead family.

LMAO oh with the drama

how do you think they run the school genny? where your kids go to school ? its in the basement with a pipe to the roof And who is going to mount a cracked pipe anyway?
BUt for arguments sake you should weld the fittings ...

Posted: 7/28/2010 4:53:07 AM EDT

[#22]

That muffler looks cool!

Posted: 7/28/2010 4:54:42 AM EDT

[#23]

Quoted:

Quoted:
I put a car muffler on my generator and it made no difference at all. It was loud as hell both ways. The muffler started to turn blue from heat so I put the original back on to avoid damage.

Had the same experience. Don't know where I went wrong.

Hurricane Ike hit here in Ohio and my Son was out of power for 2 weeks on a well. He borrowed an open frame genny and the muffler mod made NO difference either. The mechanics stethoscope told us that most of the noise came from the intake and valve train.

Some of the open frame gennys like in the OP are just plain noisy. Only a doghouse will shut them up.

Posted: 7/28/2010 5:12:22 AM EDT

[#24]

Quoted:
If this is a reed valve engine I would be concerned that additional backpressure would lead to additional heat in the cylinder head and likely damage the valve. There is a reason that the stock exhaust is configured the way it is, and it is not because the manufacturer is oblivious to the noise it makes. At the very least I would read temperature at the exhaust port with and without the modification just for peace of mind. A loud genset that runs is better than a quiet one that doesn't.

The only reed valve 4 stroke I've ever seen was the old XR 650 honda, and that was a fix to put a high duration cam in a large one lunger. I'm not concerned about it making much more back-pressure as it is essentially going from a 3/4" pipe to a 1-7/8" pipe and then to a muffler designed to handle a lot more airflow then this engine will make.

Quoted:
If I understand correctly, this is what you have:

Engine > Coleman 6K muffler > 1 7/8" pipe > 1 7/8 flex pipe > HD muffler

that makes two mufflers in series?

Two mufflers in series, yes. Although the first one isn't really a muffler.

Posted: 7/28/2010 9:26:02 AM EDT

[#25]

Quoted:
I put a car muffler on my generator and it made no difference at all. It was loud as hell both ways.

The original muffler on some generators is a lot louder than on some others. If your original muffler is doing a decent job, most of the remaining noise is from the engine's valvetrain, cooling fan, carburetor air intake, etc. - and that won't change no matter what aftermarket muffler you install.

Simple way of reducing noise:

The "enclosure" is made of fan-fold 1/4" thick foam insulation - It's often used under vinyl siding, and is available at Home Depot, Lowe's, etc. Leave one side open to provide air flow, pointing it away from your house, neighbors, etc.

It's been tested, and knocks a solid 5 dB off the noise from all three closed sides.

(images courtesy of professor95)

Posted: 7/28/2010 11:22:05 AM EDT

[#26]

That is really impressive. Or better yet because it is a Harley muffler ...positively badass.

H-D ad

Posted: 7/28/2010 11:57:08 AM EDT

[#27]

Quoted:

how do you think they run the school genny? where your kids go to school ? its in the basement with a pipe to the roof And who is going to mount a cracked pipe anyway?

BUt for arguments sake you should weld the fittings ...

Usually they use schedule 40 pipe, not exhaust tubing. But as long as it doesn't rust out.. Usually you enclose the generator room and vent it under power which flushes out any leaked exhaust, as well as making the room slightly negative which stops any leaks into the rest of the house/hospital/building.

I wouldn't put a generator in the basement with out some sort of air exchange system.

Comm

Posted: 7/28/2010 2:48:00 PM EDT

[#28]

Quoted:

Quoted:

how do you think they run the school genny? where your kids go to school ? its in the basement with a pipe to the roof And who is going to mount a cracked pipe anyway?

BUt for arguments sake you should weld the fittings ...

Usually they use schedule 40 pipe, not exhaust tubing. But as long as it doesn't rust out.. Usually you enclose the generator room and vent it under power which flushes out any leaked exhaust, as well as making the room slightly negative which stops any leaks into the rest of the house/hospital/building.

I wouldn't put a generator in the basement with out some sort of air exchange system.

Comm

By the time you got done building the air exchanger and all the sealing up of the room and multiple redundant CO detectors to make it safe a Honda EU series looks cheap indeed.

Posted: 7/28/2010 3:12:53 PM EDT

[#29]

Got the parts, gotta get the project done.

[ARCHIVED THREAD] - I made a loud generator less loud. $30 fix.

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