Author Topic: My Attempt At Quieting My Generator  (Read 10600 times)

Offline Dirt Rider 3006

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My Attempt At Quieting My Generator
« on: October 22, 2008, 06:41:54 PM »
I've had this B&S Powered 4250 watt generator for about 15 years now. It has about 150 hours on it now. Most of that is from just running it for an hour or two every other month. Just to put a load on it and make sure it runs. I've changed the oil every 6 months and rotate the "Stabalized" gas on the same interval. But the thing is LOUD !!!!

I found this webpage

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

Then decided to give it a try.



(Above) Here's the standard soup can muffler. It has a 3/4" npt thread on the end.
Note the two 1/4-20 tapped holes for using a flange instead of the NPT hole. I'll use a flange when I plumb in my new muffler.

So I put a few tools to work here. My bandsaw, drill press, my small cnc mill, cordless drill, beltsander, tin snips, etc. you get the idea.



(Above) My bracketry in it's original form. I had to skeletonize the brackets because all they did was absorb and hold heat. I made a plate that bolts to the bottom of the motor and another bracket which bolts to the generator. Those hold a vertical plate up which the muffler cradle mounts to.



(Above) Here's a pic of the exhaust end of the muffler. You can see the muffler cradle and generator bracket pretty well here. As it is pictured, the bracket that bolted to the generator blocked the airflow over the generator.

I mounted everything to the motor/generator assembly rather than using the frame. There is just too much travel in the rubber mounts  connecting the motor and generator to the frame to even think of using some "flex" tube and mounting the muffler to the frame. It would just wind up cracking from flexing and vibration.



(Above) Here's the brackets, again, that I skeletonized in order to reduce thier mass and add some more surface to radiate the heat. I also machined around the tapped holes to reduce surface contact between each of the brackets. It's funny, these brackets started as cardboard templates that I cut out and taped to the generator and to each other in order to obtain the dimensions for everything. They certainly have come a long way from ragged cut outs of carboard.



(Above) Here's all the bracketry installed. Now I have unobstructed air flow from front to back of the generator. What I found really amazing was that after 60 minutes of running under load I could comfortably touch all the brackets, except top half of the bracket that holds the muffler cradle.



(Above) My header pipe with an angled baffled on the inside. My previous header pipe did not have an angle on the inside and in turn, after 30 minutes or running under load, it was glowing red. The exhuast gas had to go around a 90 degree turn. I'm sure I was getting some serious back pressure and the was contributing to the heat in the area.



(Above) Here it is all installed ready to rock. One thing to note. On the clamping bands which hold the muffler in the cradle I added a nylock nut as a lock nut to keep the bolts from backing out. I did not tighten the muffler in the cradle. I just snugged it up and the used the nuts to keep everything secure.



(Above) Here's my Gentran in my basement. This whole set up will run my furnace, refrigerator and a few lights at less than half load with plenty of power reserved for startup of the fridge and the circulator fan for the furnace. Need to get that woodstove installed...

Once I got it all set up and running the results were not too bad, but if I had spent $150.00 to $200.00 having the brackets made and such I would not be too happy. I am happy with the results of my time and the minimal amount of money I put into the project. Oh heck, I had a ball making this stuff and also shared some quality time with my son while doing it.

The exhaust noise was quieted significantly. You could hear the whirl of the generator and internal engine noise very clearly now. My wife came home and her first remarks were "I can still hear it, it's not any quieter!". With that said, just the fact that she was talking to me and not raising her voice above a normal tone was evidence that it was significantly quieter. Before you could just about hear the individual bangs from every time the cylinder fired and you had to yell to be heard over it. Now it's just a low tone. Very low, you feel the exhaust more than you hear it. It makes less noise than my 5 hp B&S powered lawnmower.

After 30 minutes of running under load I checked the spark plug. Looked perfect. No color change from running lean or build up from running rich. I checked it again after 90 minutes of running and it was the same.

After running for 90 minutes I shut it down and quickly unscrewed the oil filler cap and inserted a thermometer into the oil. It read 153.3 degress F. I can live with 153 degrees for an operating temp!

Conclusion:

I love to make stuff out of metal. I do it for a living. I had fun, as did my son. I have cutting oil in my blood.

I wanted to keep everything within the frame of the generator to keep it portable. I am happy with the results, it's far from being silent, but it's a definite improvement.

All in all if you want a real quiet generator, buy a HONDA..... If you like to make stuff and tinker around, dig out that Coleman you have stored under a shelf in your garage and do what I did...

Hope this can help somebody out.


Regards,
Tim



millerized1

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Re: My Attempt At Quieting My Generator
« Reply #1 on: October 22, 2008, 06:59:01 PM »
Nice job.
Damn, you really make me miss my mill..... I wonder if that job is still open.

Offline ElyasWolff

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Re: My Attempt At Quieting My Generator
« Reply #2 on: October 22, 2008, 09:15:33 PM »
Sweet! Wish I had a few thousand to buy an old table top mill.

Offline 19kilo

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Re: My Attempt At Quieting My Generator
« Reply #3 on: October 23, 2008, 12:05:23 AM »
excellent post. You have a very useful talent. 


tash

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Re: My Attempt At Quieting My Generator
« Reply #4 on: October 23, 2008, 07:15:24 AM »
Very nice! Great post.  :)

Offline johnh2os

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Re: My Attempt At Quieting My Generator
« Reply #5 on: October 25, 2008, 09:19:23 PM »
I like your set up, VERY nice job!

Offline TimSuggs

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Re: My Attempt At Quieting My Generator
« Reply #6 on: November 12, 2008, 07:26:42 PM »
Super cool muffler setup!  A++ on the fab job too.  I'm gonna swallow my pride here and let my ignorance show a little and ask for a definition for CNC.  I've heard the term for a long time now, but never heard the definition.  TIA!

I too have one of the big cradle generators and "noise" is an understatement.  It's so noisy I had to stop using it for work after numerous complaints from the bums in the city parks I frequently work in (Special Events Contractor).  But the noise issues did get the hamsters up and running on the wheel betwixt my ears, and in a survival scenario I subscribe to the Mr. Meagi (Karate Kid) doctrine that the only way to "win" a fight is to "no be there".  Having a quite generator setup allows me to "no be there" as far as being discovered and then having to possibly defend me and mine. 

Here's what I was thinking.  Something along the lines of an outboard boat motor with a water muffled exhaust.  It could be ran without a "muffler" at all and branched off into several buried 55 gallon drums with water.  Sort of like an exhaust "bubbler".  One of the functions of a muffler is too cool as well as dissipate the hot exhaust gasses.  If you ran it without a muffler and just plumbed it out through the wall into a sand packed covered trench to the buried "muffler" drums, I think you'd get quite a db reduction.  You'd have to run your pipe into the drums from the top so it acted like a trap, but I can see several variations. 

My other idea was if you had a pond, you could lay out your exhaust pipes like a septic tank's field line and bubble up through the pond.  You'd have to use a "Y" with a valve so you could crank the generator and then divert the exhaust into the pond piping slowly to blow out the water.  And of course something tells me your little fishies are gonna be spending some time floating too.  Not perfect, but something to think about.

Tim Suggs
Birmingham, AL USA!

Offline Dirt Rider 3006

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Re: My Attempt At Quieting My Generator
« Reply #7 on: November 14, 2008, 07:32:04 PM »
Super cool muffler setup!  A++ on the fab job too.  I'm gonna swallow my pride here and let my ignorance show a little and ask for a definition for CNC.  I've heard the term for a long time now, but never heard the definition.  TIA!

I too have one of the big cradle generators and "noise" is an understatement.  It's so noisy I had to stop using it for work after numerous complaints from the bums in the city parks I frequently work in (Special Events Contractor).  But the noise issues did get the hamsters up and running on the wheel betwixt my ears, and in a survival scenario I subscribe to the Mr. Meagi (Karate Kid) doctrine that the only way to "win" a fight is to "no be there".  Having a quite generator setup allows me to "no be there" as far as being discovered and then having to possibly defend me and mine. 

Here's what I was thinking.  Something along the lines of an outboard boat motor with a water muffled exhaust.  It could be ran without a "muffler" at all and branched off into several buried 55 gallon drums with water.  Sort of like an exhaust "bubbler".  One of the functions of a muffler is too cool as well as dissipate the hot exhaust gasses.  If you ran it without a muffler and just plumbed it out through the wall into a sand packed covered trench to the buried "muffler" drums, I think you'd get quite a db reduction.  You'd have to run your pipe into the drums from the top so it acted like a trap, but I can see several variations. 

My other idea was if you had a pond, you could lay out your exhaust pipes like a septic tank's field line and bubble up through the pond.  You'd have to use a "Y" with a valve so you could crank the generator and then divert the exhaust into the pond piping slowly to blow out the water.  And of course something tells me your little fishies are gonna be spending some time floating too.  Not perfect, but something to think about.

Tim Suggs
Birmingham, AL USA!

Tim,

CNC is Computer Numeric Control. Here's a pretty good description from off the web.

"Computer numerical control (CNC) is a computer "controller" that reads G-code and M-code commands and drives a machine tool, a powered mechanical device typically used to fabricate components by the selective removal of material. CNC does numerically directed interpolation of a cutting tool in the work envelope of a machine. The operating parameters of the CNC can be altered via the Master Control Unit (MCU) of the machine."

The G's in the code enable you to pick the type of movement for the machine to do. They are usually followed by X Y & Z axis' (and sometimes up to 7 axis') coordinates to tell the machine where to make the selected movements.

The M's in the code tell the machine to turn on/off the spindle, coolant, and such.

With the advent of CAD/CAM (Computer Assisted Drawing / Computer Assisted Machining) writing code has become much easier. You draw the part you want in CAD, 2- dimensional or even 3 dimensional, and use CAM to select the features drawn and write the code to make the movements of the machine. I've machined some moderately complex 3-D parts that have had over 150,000 lines of code.

Below is a neat pic of a 5 axis set up:



Axis 1(x) - Table left & right
Axis 2(y) - Table in & out
Axis 3(z) - Spindle (cutter) up and down
Axis 4(A) - Trunion rotation
Axis 5(B) - Workpiece rotation

Now as far as quieting your generator, I would seriously consider getting a pair of Honda EU2000i Inverter-Equipped Generators. They are whisper quiet, very portable and sip gasoline.



Now here's the drawback, they are about $1k each.

You can work all you want to quiet your generator with water barrels and all kinds of plumbing and never get a good result. With mine, there is a huge improvement sound wise, but it is far from stealthy. I have heard one these little Honda's run and I was astounded at how quiet it ran. One pair of these would certainly provide me with enough electric power to keep me and my family very comfortable. Furnace, refrigerator, and some lights are all we need.

I do plan on picking up at least one of these little wonders when some extra cash suddenly appears in my wallet and then another when some more cash appears. The versatility they have would be a huge asset post SHTF. It's something to think about.

If you have the cash, by all means go for it, if not, get creative with what you have and figure out how to make the most of it.

Sidebar.. I've heard that burried drums filled with river rock also work great as sound absorbers for motor exhaust. Now you'll need to build some sort of enclosure to islolate the engine noise without disrupting air flow to cool the engine (if it is air cooled), now if you have a water cooled generator, you could completely enclose the noisy stuff in a sound proof box and route the radiator outside of it where the only sound from that would be a fan to blow air over the fins of the radiator.

Keep us updated on what you experiment on and the results.

Best Wishes & Good Luck....

Offline TimSuggs

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Re: My Attempt At Quieting My Generator
« Reply #8 on: November 14, 2008, 11:07:38 PM »
Thanks for the definition!  I have always understood "what" CNC was, just never heard the actual term for the acronym. 

Another podcast I listen to is The RV Navigator (http://www.rvnavigator.com) and when they were towing a 5th wheel travel trailer around behind them they used one of the 400i Honda generators and I remember the host talking about how quite they were AND that they could be plugged together.  They just left theirs in the bed of the tow truck and ran it in there and unless you got within about 10 feet of the truck you never knew it was there.

I hope I do get to try out my "stealth water muffler" sometime in the near future, and I will pass along the results.

Tim Suggs
Birmingham, AL. USA!