Jeff's Muffler Experiments

If Jeff can run a Listeroid in his neighborhood with his neighbor's blessing, so can you!

The following is a message from Jeff...

Hi, George!
I think I finally have my muffler design perfected! When you are outside with the garage door closed, all you can hear is the Lister ticking away; no audible exhaust noise at all. Once you get to the end of my driveway, you really can't hear anything at all. The final trick was to stiffen the top of the barrel with a disk of plywood over some acoustic paneling. A cloth strap holds everything tight. The trash can full of sand that the barrel is in helped, but there was still some noise from the top of the barrel flexing. The plywood cured that.
I ran a fuel test to see how much the fuel use was affected by the muffler. I did a single run at 1500W load, then extrapolated that to my previous runs. Fuel use increased by a few percent; I've attached some Excel graphs.
All in all, I think it works well. The noise is greatly reduced, with fuel economy hardly affected at all. I'm confident I could run it at all hours of the night and no one would complain.

Above is the corner of Jeff's two car garage, neighbors are close by.

Neither Jeff or George has obtained any kind of certification from anyone for a set up like this. If you do this, you become personally responsible to engineer for fire, carbon monoxide levels, and all the other related things. 

I think this high temp flexible hose Jeff found is most interesting, a person wonders if the engine might scavenge better with a reed valve on the inlet of the barrel, and what the ideal size of the pipe might be from the outlet of the barrel to the muffler. As Jeff has mentioned, a more constant flow of exhaust gas versus the pulses of exhaust gas has a bearing on the overall noise level of the power plant.

As we look at what Jeff has done, it becomes obvious that there's room to 'tune' this design, and customize it for your environment. 

If you are building a stationary power plant, weight is less of a concern, potential for experiments become endless.

Tom Miller of Olean, NY, was kind enough to send me a tape of old oil field engines running as they were installed in his area. Of great interest to me was some of the exhaust systems that ran underground some distance from the engine before the exhaust came to the surface, in some instances, water was fed into this exhaust system to 'muffle' the exhaust note.

Following are some thoughts that might be worth experimenting with. I would imagine all of these things have been done elsewhere and probably many years ago.

If we were to:  Dig a hole in the ground, place a vapor barrier inside the hole, Insulate our barrel in rigid foam or other insulating material, and then fill the hole with pea gravel or ??. This should effectively de-couple the exhaust pulses from the surrounding ground/structures.

If we were to add some liquid soap and/or water wetting agents, would it become an more effective scrubber? What about those oil eating bacteria we read about? if we place a simple thermostat and valve between the condensing surfaces (condenser) and  the sump, can we maintain some ideal temp and container for our bacteria to thrive?  If the water in the muffler got real warm would the water vapor create an even more effective 'scrubbing' action' for our exhaust system?

If we run the exhaust upwards for some distance after the scrubber, would our vapor condense on the exhaust walls and allow us to gravity Feed the water back into the sump of the muffler?

Will the reed valve increase the scavenging efficiency of the engine and produce more power or efficiency?

In conjunction with the reed valve, can we now tune the gate valve to create a more constant stream of exhaust gases and cut down on any of the noise created by these pulses traveling through surrounding materials.

I mention these things to provide a spring board for your ideas,.... there will be lots of them, and few of them will be new...


Jeff... as always, thanks for sharing you work with the rest of us!


All the best,