Adding a muffler to a portable gen

kpm · Aug 19, 2010

Anyone try this? If so, is it worth doing?

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

kpm · Aug 19, 2010

It does not seem that hard and the parts don't look all that expensive. The only variable is to get someone to weld that part to the spark arrestor... I can't weld! I can get a nieghbor to possibly do it.

Looks like I have my next tinker project...

themcfarland · Aug 19, 2010

I have the same page marked and have talked about doing it.. I get a lesson in weldin this weekend. and have plans to do mine after I get better..

kpm · Aug 19, 2010

themcfarland said:
I have the same page marked and have talked about doing it.. I get a lesson in weldin this weekend. and have plans to do mine after I get better..

Great minds think a like. Take pics and pass along your experiece when done.

thanks!

themcfarland · Aug 19, 2010

I am going to pull a muff from the junkyard tho.. not paying new

herohog · Aug 20, 2010

Guys, there is a HUGE issue with that plan... it is an expensive waste of time. The auto muffler is designed to handle the sound and pressure waves of a 4 to 8 cylinder LARGE displacement engine. It is the most useless part they have on there. Years ago my dad tried that and wound up covering the car muffler with gravel to deaden the sound as the muffler did so little muffling it was just sad. What DOES work is you go find a STOCK muffler off of a 350 - 450 cc motorcycle and use THAT. That is designed to work with an engine of that approximate size and will do a MUCH better job of sound control.

themcfarland · Aug 20, 2010

thanks.. good thought.. I was looking at a little honda or toyota car muff at a junk yard. but you are right. I will look there.. first..

herohog · Aug 20, 2010

Like I said, BTDT

You will find that welding 2 of the in-line can type mufflers will do better than adding a car muffler. The issue is that it will add restriction and that hurts performance. A motorcycle muffler will add little restriction as long as it is off of something on the order of a 250 cc or bigger engine. Find a bike muffler that has the same size head pipe diameter as the outlet port on the stock muffler and snag that one. The length of the head pipe has little to no effect on sound so you can cut it as short as you like. I recommend a stock motorcycle muffler as they are always quieter than their after-market counterparts as long as they aren't burnt/rusted out.

Quickdraw22 · Aug 20, 2010

pangris said:
weld, JB cold weld, its all the same net effect.

False.

JB Weld will gloriously fail when you get it hot. I've found this out time and time again when I used to slather it on my cracked exhaust manifold because I was too cheap to replace it.

highstandard40 · Aug 20, 2010

The car muffler can work. I used one on a Yamaha Timberwolf four wheeler for years. It will be louder than desired if left with the large exhaust outlet. All I had to do to make it quieter was put a reducer in the muffler outlet to reduce it to about an inch in diameter. The result was very quiet.

Praesul Presul · Aug 20, 2010

herohog said:
Like I said, BTDT You will find that welding 2 of the in-line can type mufflers will do better than adding a car muffler. The issue is that it will add restriction and that hurts performance. A motorcycle muffler will add little restriction as long as it is off of something on the order of a 250 cc or bigger engine. Find a bike muffler that has the same size head pipe diameter as the outlet port on the stock muffler and snag that one. The length of the head pipe has little to no effect on sound so you can cut it as short as you like. I recommend a stock motorcycle muffler as they are always quieter than their after-market counterparts as long as they aren't burnt/rusted out.

Quickdraw22 said:
False.

JB Weld will gloriously fail when you get it hot. I've found this out time and time again when I used to slather it on my cracked exhaust manifold because I was too cheap to replace it.

You two beat me to both points -
No JB Weld for this app

Think ATV or motorcycle muffler not auto

herohog · Aug 20, 2010

highstandard40 said:
The car muffler can work. I used one on a Yamaha Timberwolf four wheeler for years. It will be louder than desired if left with the large exhaust outlet. All I had to do to make it quieter was put a reducer in the muffler outlet to reduce it to about an inch in diameter. The result was very quiet.

The 1" restriction contributed WAY more than the actual muffler did I can assure you. Back in the day we used Snuff-Or-Nots in out straight pipes. They work on the exact same principle. KILLED horsepower though because they were very restrictive!

from: http://www.dansmc.com/Exhaust_4.htm

Anyone besides me remember/used these?

highstandard40 · Aug 21, 2010

The 1" reducer was actually larger than the original Yamaha factory muffler outlet. Performance did not suffer. And the price was MUCH less than a factory Yamaha muffler. My original muffler rusted out and the price of a new one scared the hell out of me. I tried an aftermarket muffler made for the bike but it was almost as loud as straight a pipe. I visited a muffler shop and bought the smallest car muffler they had so it would fit under the bike and adapted the inlet pipe and fashioned hangers. It worked well but was still a little too loud, especially on closed throttle deceleration. Reducing the 2" outlet to 1" solved the problem. It made it the quietest four wheeler I have ever heard. And no loss of power. So it should work well on a 10HP generator.

yamatitan · Aug 21, 2010

Atv muffler with the one of those hunting silencer pieces in it FTW. Just make sure you get the muffler of a make/model that is compatible with the silencers.

http://www.landoutdoors.com/benz/index.html

El Rubio · Aug 21, 2010

I have been looking into installing a muffler designed for RV generators. You may find something for the exact engine you have. For instance, Generac has a line of RV generators as well as portable gasoline models. They probably use the same engine on similar sized models. The muffler kit looks to be less than $100.

Duck Jenkins · Aug 21, 2010

Before I bought a better gen that runs quite, I built a two panel wall that was hinged. I put it in front of the gen and it deflected the sound . The wall was made out of some scrap wood (2x's plywood0 from my shop. I used the hinges so it would fold flat and take up less room to store.

my-rifle · Aug 27, 2010

pangris said:
weld, JB cold weld, its all the same net effect.

JB Weld is bondo. Nothing more. It has very little strength. I've worked with it a lot, and it's not strong enough for this application.

By the way, the author of that article didn't mention how important it is to equalize the back pressure, so after adding that muffler you have to figure out a way to get the pressure right. Otherwise you're either damaging your engine (too much pressure) or wasting energy (too little pressure.).

themcfarland · Aug 27, 2010

I have a 13hp honda clone, they call CHONDA.. it used most parts a honda would..

I have not gone to a yard yet to look but I have to believe anything would be better than what I have now.. they thing is likely 80 db and no matter where it is sitting I have 6 ft high privacy fence and the sound bounces off of it and is LOUD~

herohog · Aug 27, 2010

Excessive back pressure will only hurt performance. In a highly tuned engine, little or no back pressure will hurt performance unless the jetting is changed to compensate. In these small engines, a straight pipe is the most efficient exhaust system you can have for one but you pay a high price in noise. Adding a muffler that is less restrictive than the original stock muffler to a stock muffler will have little if any effect on back pressure but WILL have an impact on sound.

Leonidas · Aug 27, 2010

I think you're saying that the auto muffler is okay when attached to the factory spark arrester (which is left in place) and is less restrictive than it is. Am I correct, or am I confusing 2 different posts.?

If it is correct, how does one determine restriction levels?

Thanks; I too have been sitting on that article, wanting to do the mod, but fearful of engine damage.

I have a Coleman Powermate with Honda GX 390 (13hp OHV)

Adding a muffler to a portable gen

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