# Run Your Genny For Stealth



## Backwoods

Quieten That Generator

When the lights go out here in Virginia, you can hear the generators run for miles away. I looked around for ways to make mine more stealth because I dont want to advertise that I have power at times when times are bad.

I found this to be the best option and you can get a old car muffler from any junk yard for next to nothing.


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## JeepHammer

Two things you might want to know about that little write up...

One is, 
The engine is preset for a certain amount of back-pressure, usually supplied from the muffler.

Add a high volume hose and large car muffler, and the back pressure will be lessened, and you can harm valves or pistons.

Scavenging will suck the fuel right out of the cylinder if there isn't the correct back pressure, 
And that leads to Lean cylinder, over heating piston and valves, ect.

Two is,
Your fuel efficiency will go down substantially...
Since there is no back pressure to keep the exhaust from scavenging the cylinder, you will loose raw fuel out the exhaust pipe and the cylinder won't produce as much power.

*IF* you rig up a secondary sound suppressor, clamp it to the ORIGINAL MUFFLER and don't just thread a pipe into the exhaust port or bolt an open pipe nipple on the engine!

Might be a little more difficult to do, but your engine will last a LOT longer if you do...
----------------------

Another way to keep things more quiet is to not buy those lawn mower engine generators!

Get a larger generator that has a LOW RPM ENGINE with larger displacement (or two cylinders)...

Lower RPM's means you are using the same amount of fuel,

Two cylinders or larger displacement singe cylinder means the engine isn't as sensitive to back pressure changes, and there for easier to quite, 

And with low RPM's you don't have nearly the frequency of firing noise...

I have two different Onan gensets, both 2 cylinders, both low RPM units, 
(around 1,800 RPM compared to the 'Lawn Mower' engines that turn about 3,600 RPM)
And with the factory size 'Tractor Muffler' attached, you can stand by the exhaust and talk in a conversational volume with no problem.

I started out with the Lawnmower engine units, and they just simply drove me crazy! Couldn't take it, so I started looking into what they used in RV's and large Boats...

That would be Low RPM two or three cylinder units!


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## TechAdmin

Couldn't you also build a small enclosure for it to avoid any issues that would arise from adding extra exhaust setup to a generator?


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## northernontario

Dean said:


> Couldn't you also build a small enclosure for it to avoid any issues that would arise from adding extra exhaust setup to a generator?


The enclosure would need to be vented to provide fresh air in and exhaust gases out...

which would negate the benefit of an enclosure.


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## Canadian

Build a little generator shed. You can use plywood etc. It'll protect the generator from the elements. Make sure you leave enough room for air to come in, exhaust to go out, fuel, starting, removal from the shed etc. 

Line the interior with sound insulation board - you can buy it at any home depot etc. Make sure to line the roof as well. If you're on a budget egg cartons make a decent sound insulator. Acoustic foam (looks like egg cartons) from a music store will work too. 

Face the open end of the hut towards a bale of hay or straw. It'll act as a baffle and absorb the noise. If the open end is pointed at the house the sound will bounce off the wall of the house and travel a long distance.


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## Rancher

Just remember that most small gensets use an air cooled engine. When building your enclosure you have to allow enough air for cooling as well as combustion air.


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## gman1322

*backpressure...*

According to the pics, it looks like he welded an adapter to the existing muffler already on the genny. The stock back-pressure should still be there. I plan to try this myself utilizing the stock muffler.


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## StillStanding

Better to plan your setup so you only run the genset in the morning when there's lots of other noise. Don't rely on 24 hour electricity. I have a Humphery propane light installed in my kitchen, plumbed into the bulk tank, so we have reliable continuous silent lighting without electricity. Then a wood stove for heat. Once you get those two covered it's simply a matter of water and refrigeration and you don't need to run the set overnight for that. Run it in the monring while you do a load of clothes and take showers and then shut it off.


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## Halfway

Military has been sound proofing generators since they were invented. "Sound" discipline is as important as "light" discipline in a tactical environment.

Dig a pit as deep as 1/3 the hight of the generator and sandbag. Allow more room near the exhaust as it will singe the bags if it is too close.

Also, aim the exhaust to the "open most" direction keeping it away from echoing through walls, into hillsides etc.

Here are a couple links to simple solutions as well. I have never heard of the companies, but the ideas can be used regardless and it is likely the material can be had cheaply if you look a round.

Soundproofing a Generator

How to Soundproof A Generator


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## bunkerbob

My Kholer 12 KW genset has a sheet steel enclosure that pretty much keeps down the noise level.Also I built a concrete block wall enclosure about 5 feet high around it leaving a few vertical grout joints open on the back side for additional air flow. Its very hard to hear from the road about 200 ft away. The enclosure also keeps prying eyes off it and protects it.


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## Halfway

bunkerbob said:


> My Kholer 12 KW genset has a sheet steel enclosure that pretty much keeps down the noise level.Also I built a concrete block wall enclosure about 5 feet high around it leaving a few vertical grout joints open on the back side for additional air flow. Its very hard to hear from the road about 200 ft away. The enclosure also keeps prying eyes off it and protects it.


Concrete works well and adding sandbags really cuts the additional db's.

Good call on creating air access.


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## Tribal Warlord Thug

flez pipe from the exauhst to a 55 gallon barrel full of water.........sounds like a bubbling creek.......lol


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## bunkerbob

rabidcoyote666 said:


> flez pipe from the exauhst to a 55 gallon barrel full of water.........sounds like a bubbling creek.......lol


I live in southern Ca, bubbling creek? no such thing around here, then it would draw attention!!!:2thumb:
Does sound like a good idea though.:congrat:


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## Nutcase

*Soundproof Generator*

I have a Powermate generator that A friend helped me build a sheet plate enclosure with a light steel skeleton bolted to a heavy (200 lbs) concrete slab that the generator is also bolted to.

For the exhaust we added a simple automotive style exhaust pipe bolted to the exhaust plate.

For the fuel we added a standard PVC 6" cleanout screw access above the generator fuel fill cap. I still need to add some sort of lock to that but overall it looks solid and well protected.

I live in a very urban setting (50' off a street and 10' from my neighbor) but a friend 3 houses up simply chains his to his porch pillar.

I also had an electrician install a control box/safety switch to my electrical box. All I have to do is start the generator and switch the circuits from line to generator and I have power for my TV, Lights, Computer, Frig/Freezer and Furnace.

I also have a 55 gallon drum of gas to get me through. I just got a second that I will slowly fill.

I have one to two months of food/fuel ready so if the SHTF I won't be one of the sheeple scrambling the end result wil be 6-12 month supply. Also gathering some barter items.


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## UncleJoe

rabidcoyote666 said:


> flez pipe from the exhaust to a 55 gallon barrel full of water.........sounds like a bubbling creek.......lol


Might be a dumb question but doesn't that put excess back pressure on the engine? :dunno: If not, then I agree, great idea.


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## Tribal Warlord Thug

UncleJoe said:


> Might be a dumb question but doesn't that put excess back pressure on the engine? :dunno: If not, then I agree, great idea.


unless you running your genset excessivly i dont believe it effects the back pressure. the only thing you do have to keep in mind is that when your genset runs out of fuel, you dont want it to suck the water back up into the cylinders. ive run them a good long time like that when i lived in Nebr. (tornado ally, ice storms, blizzards...):usaflag:


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## Al-Thi'b

Backwoods said:


> Quieten That Generator
> 
> When the lights go out here in Virginia, you can hear the generators run for miles away. I looked around for ways to make mine more stealth because I dont want to advertise that I have power at times when times are bad.
> 
> I found this to be the best option and you can get a old car muffler from any junk yard for next to nothing.


Adding more back pressure can affect the fuel economy of the generator a little, keep that in mind.


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## ZoomZoom

I have most of my gensets soundproofed. The ones that aren't specifically soundproofed are at home and if SHTF, the area would be secured from a distance or we'd just go to the BOL.

Here's my issue now... How to maintain and operate it if there's nuclear, biological or chemical conditions? The genset needs to be outside of the breathing area as you don't want it sucking up your good air and exhausting itself in an area you want to breathe. I'm thinking of connecting up a 500 gal aux fuel tank and a remote electric start to the bigger generators and saying the heck with the small ones that are pull start.


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## Al-Thi'b

bczoom said:


> I have most of my gensets soundproofed. The ones that aren't specifically soundproofed are at home and if SHTF, the area would be secured from a distance or we'd just go to the BOL.
> 
> Here's my issue now... How to maintain and operate it if there's nuclear, biological or chemical conditions? The genset needs to be outside of the breathing area as you don't want it sucking up your good air and exhausting itself in an area you want to breathe. I'm thinking of connecting up a 500 gal aux fuel tank and a remote electric start to the bigger generators and saying the heck with the small ones that are pull start.


Pipe the exhaust through the air exhaust system.


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## ZoomZoom

The exhaust is easy and I'd do just that.
It's the air intake that I need to do something with. I don't want it drawing in "clean air" that is for breathing. I guess I'll have to run a duct in from the dirty air area to the engine to supply the air it needs.


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## Al-Thi'b

bczoom said:


> The exhaust is easy and I'd do just that.
> It's the air intake that I need to do something with. I don't want it drawing in "clean air" that is for breathing. I guess I'll have to run a duct in from the dirty air area to the engine to supply the air it needs.


Hook it up to the fresh air intake using a splitter valve.


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