Making a standard Gen Quieter

jkam

nomadic man
I would think an enclosure is the best at quieting down one that isn't already in one.
The Onan QD 10k in my buddys Winnebago is surprisingly quiet. It's completely enclosed.
 

dbhost

Member
Assuming running the exhaust into water will make a lot of difference, which I doubt - 12 hours running is likely to evaporate a few gallons of water so the level will need to be automatically maintained. May need to augment storage capacity to cope.
I live very close to marinas with lots of boats and I can assure you, water does very little to quiet engines down unless it gets sucked into the intake.
 

robert

Expedition Leader
Holy thread resurrection. A glass pack is one of the worst mufflers since they were designed for muscle cars. Some of the small engine manufacturers make a quieter muffler for their engines, you have to check with them though. As noted, a lot of the noise is from the rattly contraption itself (Hondas for example are much tighter tolerances and quieter). Put sound adsorbing pads on the inside of any body panels, use rubber or urethane bushing to isolate the motor from the metal frame, coat the metal frame with bed liner, and install a better muffler. Back when I did environmental work part of that was electrofishing. We cut the muffler off the Coleman generator and welded on a bit larger one which helped- remember, sound is a logarithmic function, not linear. I've seen several people remove the muffler and install a flange on the exhaust port. When they got to camp they would dig a hole and run a flexible hose from the generator exhaust to the hole. It actually helps some.
 

Mwilliamshs

Explorer
I live very close to marinas with lots of boats and I can assure you, water does very little to quiet engines down unless it gets sucked into the intake.
Being out on the water makes sound carry very well. Two boats moored a few hundred yards apart can converse between them quite normally if the water is calm and ambient noise is scarce. It acts like an amplifier. It's why Jesus gave sermons from a boat to crowds on the shore. That trait of water has nothing to with its ability to quiet exhaust forced through it. It's a dense, cheap, readily available liquid that works well as a muffler. My two-stroke 9.9hp evinrude run with water hose earmuffs (exhaust open to the air) is over 3x louder than the same engine run in a barrel of water.

So a boat that's using say 250hp can be very quiet to those near it but if the exhaust breaks the wake it's gonna be loud on the shore. Likewise, the high-winding seadoos zipping around on 50hp can be obnoxiously noisy as their exhaust is constantly breaking the wake as their hulls noisly bounce across the surface. If water wasn't a very very effective muffler, every lake would sound like a nascar race. Bear in mind, boats use no muffler other than the water so if it didn't work, it wouldn't be debatable.
 
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dbhost

Member
Being out on the water makes sound carry very well. Two boats moored a few hundred yards apart can converse between them quite normally if the water is calm and ambient noise is scarce. It acts like an amplifier. It's why Jesus gave sermons from a boat to crowds on the shore. That trait of water has nothing to with its ability to quiet exhaust forced through it. It's a dense, cheap, readily available liquid that works well as a muffler. My two-stroke 9.9hp evinrude run with water hose earmuffs (exhaust open to the air) is over 3x louder than the same engine run in a barrel of water.

So a boat that's using say 250hp can be very quiet to those near it but if the exhaust breaks the wake it's gonna be loud on the shore. Likewise, the high-winding seadoos zipping around on 50hp can be obnoxiously noisy as their exhaust is constantly breaking the wake as their hulls noisly bounce across the surface. If water wasn't a very very effective muffler, every lake would sound like a nascar race. Bear in mind, boats use no muffler other than the water so if it didn't work, it wouldn't be debatable.
Fair enough. Good explanation too.
 

DzlToy

Explorer
LOTS of engineering goes into NVH or Noise, Vibration and Harshness, in the automotive world. For these reasons, you barely hear a modern car at idle or when coasting down the road.

When you stand on the right pedal, some sound comes from the intake, some from the exhaust and some from mechanical actions, i.e. pistons, valvetrain, etc. New diesel engines (pickup trucks) have received HUGE improvements in mechanical noise reduction over the last 5-7 years, so much so, that they now sound like gasoline cars at idle.

A cheap or off name brand generator will see NONE of this NVH engineering. So, while you may be able to add a better exhaust or install some generator box liner from a company like Cascade Audio, you will not be able to do anything about the noise that the engine makes.

There is a reason that Honda generators are the quietest and most reliable on the market: Honda dumps millions and millions of dollars into making them that way.

Honda EU2200 costs about $1000

Cong Shen 2000W generator costs $400.

Why do you think that is??

If a 3500W genset is not enough, I would suggest two 2000W Honda or Yamaha generators, thereby offering flexibility, redundancy, and most importantly quiet.

As you probably know, used Honda generators hold their value very well, but can be picked up for $600 - $800 with some shopping. To quote an old commercial, "Buy it once, buy it for life."

You will be time and money ahead making a long term investment, instead of trying to make a cheap, loud generator, quiet.

If you insist, a large volume muffler will absorb the most sound, probably not something that you want on your generator and an in-your-face example of why most small engines, i.e. weed trimmers, chainsaws, etc., are so damn loud.
 

dbhost

Member
LOTS of engineering goes into NVH or Noise, Vibration and Harshness, in the automotive world. For these reasons, you barely hear a modern car at idle or when coasting down the road.

When you stand on the right pedal, some sound comes from the intake, some from the exhaust and some from mechanical actions, i.e. pistons, valvetrain, etc. New diesel engines (pickup trucks) have received HUGE improvements in mechanical noise reduction over the last 5-7 years, so much so, that they now sound like gasoline cars at idle.

A cheap or off name brand generator will see NONE of this NVH engineering. So, while you may be able to add a better exhaust or install some generator box liner from a company like Cascade Audio, you will not be able to do anything about the noise that the engine makes.

There is a reason that Honda generators are the quietest and most reliable on the market: Honda dumps millions and millions of dollars into making them that way.

Honda EU2200 costs about $1000

Cong Shen 2000W generator costs $400.

Why do you think that is??

If a 3500W genset is not enough, I would suggest two 2000W Honda or Yamaha generators, thereby offering flexibility, redundancy, and most importantly quiet.

As you probably know, used Honda generators hold their value very well, but can be picked up for $600 - $800 with some shopping. To quote an old commercial, "Buy it once, buy it for life."

You will be time and money ahead making a long term investment, instead of trying to make a cheap, loud generator, quiet.

If you insist, a large volume muffler will absorb the most sound, probably not something that you want on your generator and an in-your-face example of why most small engines, i.e. weed trimmers, chainsaws, etc., are so damn loud.

While well outside of any available budget I have at this time, I agree with the concept of, if you absolutely need more than 2KW, using 2 of the 2KW Honda, or similar gensets with the pairing cables.

Now while I agree to a certain extent that there is time, money and R&D involved in NVH on the Honda, there is no lack for other, quiet generators on teh market that have gone under similar NVH R&D in their engineering / design process that cost considerably LESS than the Honda. I know there are plenty of folks that will disagreee with me on this, but you are definately at least partially paying for the name and marketing for Honda. Nothing wrong with that, it just is what it is. I mean you always hear about Honda Reliability, but the people I know that for example have owned Honda Odyssey vans have to the last person wished desperately they never bought them, prone to major transmission failures and air conditioning failures that cost a fortune to fix... While most likely a fluke, it just shows that just because you have a brand XZY product doesn't mean that manufacturer won't put out duds. For example Aston Martin who is known for beautiful and at least reasonable high end performance luxury cars, produced the Aston Martin Lagonda, which is consistently rated one of the worst cars ever built, in the same category as the Ford Pinto, Trabant, and AMC Pacer.
 

plh

Explorer
For example Aston Martin who is known for beautiful and at least reasonable high end performance luxury cars, produced the Aston Martin Lagonda, which is consistently rated one of the worst cars ever built, in the same category as the Ford Pinto, Trabant, and AMC Pacer.

Its back:

 
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