Suggestions quietting a Briggs & Stratton 5500w generator?

I tried going down this road, with a large tractr muffler that did a basically perfect job. The result was VERY disappointing, as it turned out that most of the noise was from clanking, not from exhaust.

i

if its a flathead i bet it will never be quiet

I converted a Kohler 8 horse from air to water cooled for use in the bilge of a boat. Adding the water jacket and water cooled head did wonders for stopping some of the noise, but it was always somewhat noisy. As others have alluded, you're highly unlikely to get a flat head air cooled engine to run quietly.

Harold

B&S engines can be quieted remarkably by a simple 2-step process;

1) throw engine in trash 2) replace with Honda ;)

Your genny was an Onan diesel, wan't it? Diesels clank considerably more than Briggs & Stratton gasoline engines.

No, it was a Lombardini diesel on some frame generator that I long sold, mostly due to impossible noise and difficulties starting.

The Onan diesel is a completely different story, I put it in a lead lined enclosure. You can see the enclosure here.

That's true, I agree.

i

I put a SuperTrapp Quiet muffler on my 12hp welder/generator and the results were amazing:

Yeah, they do, what with skirt slap and all that jazz...

But my (very old model) upright 10HP Briggs makes so much whizz and clatter that you can clearly hear the engine noises over the exhaust-- and it's just muffled with one of those single-baffle pancake mufflers you buy at K-Mart.

That was why I opted not to put a better muffler on it. 'wouldn't do much...

LLoyd

Yeahbut the Honda is gonna cost me more than $2 Saturday morning. Gerry :-)} London, Canada

I found this is the case with small 2 cycle engines as well.

I read something on the internet awhile back that said the average "quiet" residential area had a background noise level of 50 or 55 db(A) (I can't remember which). At night the figure dropped down to about 40 or 45 db(A), as I recall.

The Honda EU series generators provide a partial solution to the problem, but you pay for it both in the price and in power reduction. The Honda EU3000is, for instance, costs about $2000 and only puts out

2800W with a surge capacity of 3000W. A good, used 5500W B&S generator on the otherhand might only cost $400 and probably puts out 5500W with a surge capacity of 8500W.

The Honda is rated at 58 dB(A) at full load. However, I read somewhere that they don't measure in the direction of the exhaust. So, the actual figure could be somewhat higher. Your generator probably has a noise level of about 80 dB(A). So, to equal the Honda, you would need to reduce the noise level of your generator by about 20 dB(A).

The bad news is that a reduction of 20 dB is a lot more than you might think. My understanding is that this amounts to reducing the noise power coming from your generator by about 99.9% which is difficult to do. Also, while we are talking about bad news, even 60 dB might bother your neighbors, especially at night. The good news, of course, is that if you can do it, you can save alot of money and also have a generator that puts out alot more power. Also, in the way of good news, I have read that B&S generators are very good generators (except for being very loud).

The only way that you are likely to get a large reduction in the noise level of your generator is by completely enclosing it in a box. My guess is that almost any kind of a box constructed of random materials, with no openings, would give you an immediate reduction of at least

10-15 dB(A). If you were to build a box using optimum materials and good construction techniques, you might be able to get a reduction of 25 db(A) or more. However, this means that you are going to have to pump air into the box for combustion and cooling.

Once you add some sort of a fan and air ducts to the box, the noise level is going to go up again. Another problem is the possibility that you might not be able to get enough air into the box to cool the engine and generator properly. Assume, for example, that the maximum ambient temperature spec of the Briggs & Stratton is 104F (which I believe it is) and the ambient temperature is 100F, you are obviously going to have to pump a lot of air into that box. On the otherhand, if it's the middle of the winter and the temperature is 35F, you won't need alot of cooling air.

Recently I had my old gas furnace replaced and I saved the blower fan and motor. I'm thinking this might work pretty good for ventilation if I decide to go the box method. My guess is that you could probably buy these from a local furnace guy pretty cheap. Air ducts, by the way, probably have to be constructed with some bends (U-turns) to reduce noise. My understanding is that the duct work also has to provide some changes in hole sizes. In otherwords, you might need to go from an 8" duct to several 4" ducts and back again, etc.

Reducing generator noise is a very difficult thing to do and I doubt if your plan to modify the exhaust will help much. Most people, now days, probably just take the easy (but more expensive) way out and buy a Honda and make do with the reduced power capability.