Quiet Muffler Designed

[dvdriz 16]

I was tinkering around the other day and tried to apply automotive muffler designs, using noise cancellation chambers, to build a muffler for my tractor. I ended up using 14GA sheet metal to build a cylinder with three chambers. Believe me there was no science involved but it sound really great! It has a deep throaty sound at idle and is amazingly quiet at running speed. In fact I can hear other rattles from the engine that I could not hear before. Here is a rough drawing for anyone that would like to experiement. The pipes are 1" iron pipe and the rest is 14GA sheet metal. Brazed it all together as I slowly folded it into a cylinder shape and finally brazed the seam shut. The holes in the pipes are 3/16". [img]/club2/attach/dvdriz/Quiet Muffler.jpg[/img]

[Bruker 2]

I like your design but I need something a little more compact. I've been tinkering with an idea for a quiet muffler for my Coleman generator with an 8hp Briggs. A 3/4"x5" pipe nipple coming out of the engine which connects to a 3/4"x1-1/4" 90 degree elbow which connects to a 1-1/4"x6" nipple with a cap on the end of it. The 6' length of 1-1/4" pipe will have about 20 3/16" diameter holes drilled in it and it will be stuffed with stainless steel scouring pad material. Let me hear your approval or disapproval of my design.:)

[comet66 0]

That's a pretty good idea Keith. Thanks

[ehertzfeld 1]

Pic's man were are the pic's! Elon

[HubbardRA 19]

I'm working on a design myself. Got some of the metal. Hope to get the 4 inch tubing this weekend. If it works, I would like to have another member also evaluate the design, then I will post it for everyone. I have two different designs to try. At least one of them is a short design.

[sandyhillbill 12]

one thing you need to consider is creating too much back pressure with these homemade exhaust systems.

[BLT 717]

quote:

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Originally posted by sandyhillbill
one thing you need to consider is creating too much back pressure with these homemade exhaust systems.

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Bill the correct statement is "have to consider" as to much back pressure will take out an exhaust valve about as quick as a New York second. It will also increase crankcase blow by if the pressure gets to be to much.

[Kent 435]

These have been used for high-performance car mufflers for a long time -- but you have to make sure the chamber is big enough so that you can have enough holes in both the input and output tubes not to build back-pressure... I had a pair of these, with 1.5" tubes, about 24 inches long, mounted on a high-performance VW (overize pistons/jugs, 9.5:1 compression compared to 7:1 stock, "3/4" cam, dual webers (single throat), mechanical advance distributor, a little head work... real throaty sound at low RPM and going slow, but about as quiet as a stock muffler at high RPM.... Ran a single one a more stock engine. The flip-side of back-pressure is that some is needed, in order to have maximum torque at low RPMs. Too much and you overheat the exhaust valves at high RPMS... You'll even notice this on V-8 pickups with cat-back exhausts -- dual 3" pipes will actually lose lowend torque over a stock system... VWs were notorious for exhaust valve problems, and these types of mufflers were tested very heavily.... I've wished many times for one that'd fit the single-cylinder Briggs...

[HubbardRA 19]

Kent, If I build a couple of prototypes, will you test them and share the results with the club? Rod

[Kent 435]

Sure, I'd love to have a quieter exhaust on my Briggs. I'm running the OEM Nelson types on all of mine right now....

[HubbardRA 19]

Thanks Kent, My problem is that none of my three running tractors have a stock muffler on them. 61 Wards has the vertical stack with motorcycle pipe on it. AC716H has an aftermarket can muffler. AC713S has a Cub Cadet muffler. I don't think that my judgment would be considered to be as valid as someone who has machines with stock Simplicity mufflers on them. I may get to start building on them this weekend.

[stumpy 0]

Pretty cool guys. I've been around some gen-sets as of late that could sure use some quieting. Reckon I'll stick to my verticle stack and rain clapper on the B though...'cause it just looks and sounds so cool...unless, of course, you happen to lean up against it while B.S.'n after the thing has been running....ouch.

[Al 6]

Hi, If you are interested I can help you with the back pressure testing, we do it when we certify our kits. I can't give you Briggs specs, but I can Kohler and I can't believe that they are that far apart. I will explain how to make a manometer to do the test. We use a calibrated guage, but it will be easy to make a water manometer. Will get the specs tomorrow. Al Eden

[HubbardRA 19]

Thanks Al, When I get a couple prototypes built, maybe I could send them to you for pressure testing, then you could send them to Kent for testing on the tractors. We can make it a club project. If we get a good design I will post drawings of the construction afterward.

[dhardin 0]

Looks great and sounds good to me. Be a great club project.