My idea is to modify a round baffle plate that fits around the spark
arrestor exhaust port . Hollow it out so that there is no baffle but
the mounting surface remains, attach a piece of metal flex pipe flex
pipe to the remaning surface ring of the hollowed out center of the
baffle plate about six feet out. I believe this will lower exhaust
noise of the generator without any back pressure to overheat the
air-cooled engine. I got this idea for being in a service station where
an emissions inspection was being performed. A large blower motor
exhausted tailpape emissions , very loud. When a long rubber type hose
was attached to vent exhaust gases to outside of area it quieted the
Loud exhaust blower . Any suggestions?Thanks, Starz
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.
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.
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
A long piece of flex pipe heading off to a car muffler will pretty much
kill all the exahaust noise with very low back pressure. You need to
keep the noise enclosed in the pipe and cool it off enough. But you can
only kill about half the noise from one of these generators, a lot of
the noise is from the engine block itself.
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
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
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
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.
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