Survivalism & Self Sufficiency Topics > Do It Yourself - Projects, Ideas and How To

My Attempt At Quieting My Generator

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Dirt Rider 3006:
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

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!


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.


Nice job.
Damn, you really make me miss my mill..... I wonder if that job is still open.

Sweet! Wish I had a few thousand to buy an old table top mill.

excellent post. You have a very useful talent. 

Very nice! Great post.  :)


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