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alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

Car muffler for small generator

I'm getting to the final steps of my generator hookup which took a long time on the electrical side.
»Generator house link project - The progress..

So now in the shed in which this 3000W/4000W 6HP generator will reside, I will be doing proper ventilation and exhaust.

Since used mufflers are cheap as dirt, i figured i could add one in line with the exhaust, but I still want to figure out the proper "size" most adequate for the type of sound I'll be muffling.

Yes I know generators make a lot of engine noise even with a muffler, but that will be dampened by the shed's structure.

Now I want to limit the noise coming out of the exhaust from the shed

Would any size car muffler do the same job, or would a smaller muffler be more adequate to the type of noise being dampened?



santy
Don't Follow Me, I'M Lost Too
Premium,MVM
join:2001-06-10
Wilmington, IL
kudos:1

I really don't know the answer to your question. Have you considered possibly a motorcycle muffler? something from a single or two cylinder bike? If from a multi cylinder bike, find one that basically has an exhaust pipe/muffler per cylinder.

Might work better than a car muffler do to the motor design.
Just a thought I had while thinking over your question.
--
You don't quit playing 'cause you're OLD. You're old BECAUSE you quit playing!!



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

That's what I figured, that mufflers aren't just "sized" for the engine size, but also designed to muffle a certain type of engine.



TypeNameHere

@spcsdns.net
reply to alkizmo

»www.supertrapp.com/product_secti···CatID=35

'nuff said


Crescent
Premium
join:2003-01-22
canada
reply to alkizmo

I used to have a V 4 air cooled Wisconsin converted so 2 of the cylinders were an air compressor.
Based on the 30 HP Wisconsin engine.

Yes it was loud, cranking out 140 psi.

One car muffler did not do the job. 2 in series kind of kept it down. I was lucky to have a Stainless Steel flexible joint so the manifold did not take too much load of all that exhaust piping.
4 years of use and a hole burn through the SS flex pipe. Air cooled engines do get hot, particularly when run hard.

Perhaps run the exhaust into a metal 5 gallon bucket with some glass fiber inside, and then out.
Perhaps chill the exhaust in the bucket to cool the gasses, they do that with marine engines. Let the gas bubble up in the water.
That may cause problems in the winter!
Getting the weight off exhaust may be tough.
Harder if the engine is rubber mounted.

You may not like any of the above but just some different ideas.



dandeman
Premium,MVM
join:2001-12-05
Chapel Hill, NC
Reviews:
·AT&T Southeast
reply to alkizmo

Have done this (using small car muffler) on RV Onan generator.. They don't work well for small engines as the cfm capacity of what they were designed for doesn't lend to effective use on a small engine..

They sound like the engine is ummm farting in an oversize jug..

As mentioned in the post above... you must use flexible piping to keep the very significant small engine vibrations from trying to rattle and shake the larger muffer and piping..That noise alone will be significant and puts tremendous stress on the small engine exhaust port...

I bought a length of stainless steel flex piping that outlasted everything.

A good rv generator muffler from a RV store such as Camping World would be very effective, appropriate, but not cheap solution.


HarryH3
Premium
join:2005-02-21
kudos:3
reply to alkizmo

There was a long discussion recently over in the Home Improvement forum on this subject recently:

»Help w/generator noise

You might find some good info there also.



OZZY7
Born Again Atheist
Premium
join:2011-06-11
reply to alkizmo

said by Jack's Small Engines :
Quiet Mufflers for Small Engines & Generators

Jacks lists quiet mufflers to quiet the exhaust of large and small engines. Three types are available.
»www.jackssmallengines.com/quietm···dex.html
Super Trapp is a good suggestion but that's the wrong muffler for the application. Jack's lists 2 Super Trapps designed specifically for small-engines. Forget the car muffler.
--
You Can't Kill Rock 'n' Roll!


beck
Premium,MVM
join:2002-01-29
On The Road
kudos:1
reply to alkizmo

Just vent it out the roof with 2 bends in the pipe. It will be pretty darn quiet with just that.



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

Considering the price tag of SuperTrapp mufflers, I'll probably try a simple up pipe 2 bends.

If it's not quiet enough, I can eventually add a muffler in between the generator and pipes.

So okay, to summarized (minus muffler)

Generator ---> Flex exhaust ---> Pipe going outside.

What can I use for the pipe after the flex exhaust?

I'm thinking of using steel raceway pipes (Electrical department). I'd buy a 10 footer and cut it into sections, combined with bends and out the side top of the shed then back up.

How long is a flex exhaust anyway? (just calculating if I'd need more than 10 feet of solid steel pipe)


8744675

join:2000-10-10
Decatur, GA
reply to alkizmo

Maybe a motorcycle muffler would fit better. Not Harley Davidson pipes though. Vrrrrooooom!


8744675

join:2000-10-10
Decatur, GA
reply to alkizmo

Maybe one of these for a 150cc scooter. It would be better at muffling the combustion noise of a higher pitch engine.

»www.ebay.com/itm/SCOOTER-EXHAUST···15f1f1eb



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

1 edit

I was more thinking something like this
»www.ebay.com/itm/Honda-Gx-240-Gx···f6b927dA scooter engine is for high pitch engines. A generator isn't high pitch.



OZZY7
Born Again Atheist
Premium
join:2011-06-11

Something like that might work, but seeing as that's a non-OEM muffler listed on ebay there. I'd doubt it would be any better than the typical pancake muffler. A genuine honda muffler might work.
--
You Can't Kill Rock 'n' Roll!



OZZY7
Born Again Atheist
Premium
join:2011-06-11
reply to alkizmo

A motorcycle muffler is probably the cheapest, best bet. Like this »joelsgarage.blogspot.com/2006/03···ler.html
--
You Can't Kill Rock 'n' Roll!



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

Ok then. Cheap motorcycle muffler it is.
At least I can find this easier locally.



OZZY7
Born Again Atheist
Premium
join:2011-06-11

Well, I take it all back... I think you're right and a car muffler is best. The trick is finding the right car muffler. Check this out!

»www.youtube.com/watch?v=JeV0zH-z···=related


Maybe the secret is hooking the exhaust pipe into the muffler that's already on the genny like in the above video. IDK, but that's amazing.


Rifleman
Premium
join:2004-02-09
p1a

1 recommendation

reply to alkizmo

Pull the carb cover and filter off the generator and start it. The intake noise is worse than the exhaust.



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to alkizmo

I just realized (by looking at the parts diagram of my generator) that it has a pretty big (relatively) muffler inside the chassis.

I really should just test that generator before getting any further

Ya I never ran it yet.


Crescent
Premium
join:2003-01-22
canada

Proactive people >>> got to love ya

The Op just looks at the generator and thinks noise, maybe worries more about who lives next door, and what they think of the noise and takes them into consideration too!

I bet he says nothing when next door cranks the radio up and only turns it down when required at 10 pm or when ever the local laws say's they should.


dipweed23

join:2009-07-21
Ypsilanti, MI
reply to alkizmo

Glass pack mufflers (cherry bomb, etc) are fairly effective for this sort of thing. Keep the muffler close to the engine, and a fairly long run of pipe after it.
If you knew the dominant frequency that you are trying to dampen, you could design a resonator to go before the muffler to further the effectiveness of it. There are many calculators out there for designing resonators.

You should consider using a very short run of black pipe to come from the exhaust port to your flex pipe because it will handle the heat.
Once you have the exhaust figured out, run a fairly long run of 3 inch PVC for the intake. Just having that will reduce the noise from that end, and shouldn't starve it for air. If the intake is still too loud, a glass pack on that end will reduce the noise to barely audible.



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by dipweed23:

If the intake is still too loud, a glass pack on that end will reduce the noise to barely audible.

Well considering the generator will be inside the shed, the intake noise better remain inside the shed, so a PVC extension for the intake would just bring the noise outside.

Where would I get a short run of black pipe? I could only find 1/2" black pipe, nothing bigger.