Way OT - Generator Muffler

[Bob S.]

Well, it's Black Friday and I'm not going anywhere near a mall this weekend ! Got a small job I've been meaning to around to so off to the borg to pick up some materials.

I have a 5000W emergency power generator I got a year ago that has been very handy in here in the northeast. But like most, the damn thing is loud and you can't hear yourself think if you're within 25 feet of it. Decided it's time to tame the beast a bit so I picked up a 2' section of 6" duct pipe, two 6" to 4" reducers, a roll of 1/4" sq hardware cloth and a small roll of unfaced fiberglass insulation (pink stuff).

I saw it someplace that I can't find now but the idea is to make a glass-pack muffler. I'll make a 4" tube with the hardware cloth, wrap a layer of the insulation around that and then stuff the whole works in the 6" pipe. Put the reducers on each end and hopefully it will cut down the noise level.

Plan on just setting this muffler near the muffler that's on the B&S 10hp engine so that exhaust feeds directly into the secondary muffler. Since it's essentially like the glass-packs we used to put on the old flatheads (remember those guy's and gal's?) there is no back pressure due to baffles and the insulation absorbs the noise.

I did take a look for sites that could help me figure out how to make a baffle type muffler (noise canceling) but nada, so the glass pack seemed the best way to go rather than chance burning up a engine experimenting.

Anyone know of a better method? This generator gets wheeled out to the edge of the garage when needed, so whatever I do, needs to be portable. B&S suggests making a baffle chamber using ply and 2" think foam insulation. That would seem kinda bulky to me compared to a 2'x6" piece of duct. Besides, I'll be the only guy on the block with a glass pack on his genny......

Bob S.

[Rico]

Your muffler diameter sounds too big for the job, but now that you have it the best way is to try it.

If it isn't quiet enough try putting a divider someplace along the length of the muffler with a restriction that is a bit smaller than the stock port. The idea is to break your glass pack into two chambers of unequal volume so the pressure pulses will bounce around a bit in each chamber before escaping the smaller exits. Also make the outlet of the glass pack no bigger than the outlet of the stock muffler. ______________ | | | == === === |________|_____|

[Mark Jerde]

ISTR discussions on this at either or both of these NGs: rec.crafts.metalworking sci.engr.joining.welding

HTH

-- Mark

[Bob S.]

Thanks Mark

Bob S.

[bob]

Yeah, OT, but I had exactly the same problem. 5K generator with a vintage cast iron 9hp B&S engine. So loud it made my teeth rattle. I also happen to have a vintage Cub Cadet tractor with a 7 hp Kohler engine that runs very quiet. The Kohler has a large, 6 inch diameter muffler about 12 inches long with a 1" "tailpipe". I pulled the muffler off the Kohler and put it on the Briggs. The generator runs much quieter now, although not as quiet as I would like, but not bad for an engine spinning at 3600rpm under load. I bought a replacement muffler for the Cub. Total cost was $25.

Bob

[Mark Jerde]

You're welcome. Here's one of the more "interesting/bizarre" discussions in case you missed it:

-- Mark

[Bob S.]

Mark,

Thanks and that was a bit over the top. I got 99% of the glass-pack assembled yesterday and was going to try it on the generator but when I left the shop, there was a small blizzard going on. Decided to plow out the driveway before the temp dropped and that wet and heavy snow turned my driveway into an ice-skating rink.

Started up the snow blower and that is a 8hp B&S which is also very loud. Just for the heck of it, I held the glass-pack up to the muffler (as they call it) and it did make a difference. A snow blower with attitude!

At least that was promising and maybe today I'll fire up the generator and see how that works. Just about any reduction in exhaust noise would be welcomed. I've found a number of posts where they got innovative and adapted different sized mufflers to generators. I may go that way but for now this glass-pack idea may be enough.

Thanks,

Bob S.

> -- Mark