Author Topic: Quieting the exhaust on a SR2 motor??  (Read 724 times)

quinnbrian

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Quieting the exhaust on a SR2 motor??
« on: June 26, 2018, 03:53:56 AM »
Hello everyone, I have a generator, built around an SR2 motor, My question is , has anyone come across a way to quiet down the exhaust noise, the generator/SR2 is inside, so engine noise is not that bad, but trying to come up with an idea on how to quiet down the exhaust.  Right know, it runs though an exhaust off a F450 ford diesel cube van, works well...but was looking for better ideas....
Cheers
Brian

glort

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Re: Quieting the exhaust on a SR2 motor??
« Reply #1 on: June 26, 2018, 05:42:56 AM »

Where are you trying to quieten it, inside the shed or out?

A lot of people fail to realise how much noise the INTAKE makes.  I have read of people putting mufflers over the inlet side with a filter on the end of that.
Many have said it makes a HUGE difference.  I would have to concur with my 6/1 Roid.  Just by putting a a wadded up sheet over the inlet the sound dropped dramatically. You can try the same with the exhaust. get a big pile of rags and hold it over the outlet. If the sound drops substantially you have room for improvement. If not so much, then you are probably looking in the wrong place.
I put an automotive airbox over the inlet of my roid and there was a significant difference even just when the thing was exhausting through a couple of feet of straight pipe.  P packed that with some course steel wooll scourers and that made a significant difference as well. I went to an auto Muffler once I got hold of a suitable one.

There are many way of quietening exhaust. The ground pit is a preferred one.  I have always used large automotive Mufflers like you have.  The trick is to slow gas speed so by using an over size muffler, you can decrease the velocity quite well. I have also set up exhausts where there was an over size system and a restriction. Instead of the exhaust going out in a pulse, it filled a muffler or resonator and then bled down through a small hole.  Not too small but enough to slow the pulse to a stream.

This is a good method for a Lister given the time between pulses and the under stressed nature means there is no performance drawback.

Auto mufflers and longer pipe runs should to the trick easily but if you don't mind a bit more work on a permanent installation, a ground system is probably hard to beat. Might help any plants grow if they are sitting on top as well through the increased heat.

BruceM

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Re: Quieting the exhaust on a SR2 motor??
« Reply #2 on: June 26, 2018, 06:51:39 AM »
If you can help offset the cost by having it done when a backhoe is already there for other work, the leach-field type muffler is amazing.  You do need a bunch of 3" cinders or rock for the trench.  We put a Tee in the line going down into the leach field so that the standard Listeroid pepper pot muffler could be screwed on for diagnostic purposes if needed.  This completely eliminates exhaust noise and also cleans up the exhaust smell.  We used standard 4" perforated PVC drain pipe, and elbow and solid PVC drain pipe riser with a standard 4" galvanized vent cap for the leach field outlet.  The inlet is 2" pipe with lots of 1/2 inch holes for about 3 feet into the trench.   

Others have done large masonry expansion chambers in the ground with reported success also. 


ajaffa1

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Re: Quieting the exhaust on a SR2 motor??
« Reply #3 on: June 26, 2018, 11:10:58 AM »
Hi Quinnbrian. I run a Lister ST2 which is very similar to yours. I found that the cheapest way to silence the exhaust was to build an underground chamber with a long underground pipe to act as a muffler. You will need a shovel, one cheap plastic dustbin, one length of 3" corrugated plastic pipe and about a half a ton of concrete.

Dig a round hole 200 mm larger than the diameter of the dustbin and about 100 mm deeper.

Pour about 100 mm of concrete in the bottom of the round hole. drop your dustbin into the hole and press into the concrete. Fill the dustbin with water and ensure the bin is somewhere near level. Before  filling around the dustbin with concrete place a 100 mm piece of 100 mm plastic pipe at the bottom of the dustbin. Now fill around the bin and over the top of the pipe with concrete.

Allow to set for at least 24 hours. Using a grinder/stanley knife cut the plastic bin into bits and pull it out. you should be left with a very nice cast concrete chamber. Where the 100 mm pipe was buried, knock out any concrete that has filled the pipe.

Dig a 150 mm wide trench from that pipe to wherever you want your exhaust to vent, if you can run it down hill all the better. pour 100mm depth of concrete into the trench and press the 3" corrugated pipe into it. Cover with another 100 mm of concrete before back filling trench.

All that is left to do is to shutter the top of the chamber, drop your exhaust pipe into it and concrete the top.

In my situation, being on a hill, I ran six meters of corrugated plastic pipe, set to fall, to avoid the expansion chamber flooding. I also installed a fly mesh on the outlet to keep out the ants.

Total silence from the exhaust, doesn`t however kill the intake or mechanical noise.

Just in case you are concerned about the corrugated pipe melting and causing problems, it never has and even if it does it was only a shutter for the concrete which should last for centuries.

Bob

quinnbrian

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Re: Quieting the exhaust on a SR2 motor??
« Reply #4 on: June 30, 2018, 02:15:39 AM »
Thanks guys , I've looked at doing an under ground exhaust, but was worry about freeze up in the winter months. Would this be a problem?

BruceM

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Re: Quieting the exhaust on a SR2 motor??
« Reply #5 on: June 30, 2018, 04:29:40 AM »
No troubles whatsoever with the leach field muffler. Freezing wouldn't bother it anyway but it's below the frost line here.  The design is that of a leach field- so no issues with water.

quinnbrian

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Re: Quieting the exhaust on a SR2 motor??
« Reply #6 on: June 30, 2018, 03:23:39 PM »
Thanks Bruce, I think this will be the way to go.
Cheers
Brian

BruceM

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Re: Quieting the exhaust on a SR2 motor??
« Reply #7 on: June 30, 2018, 04:11:17 PM »
Others have reported the earth chamber type muffler very effective, also.  Bob's construction method is quite original and ingenious.  Others have use more conventional block or brick for the same good result.

The leach field approach was appealing for my neighbors, for the exhaust air filtering effect; Murphy's law guarantees the wind will be in the wrong direction sometimes, and they are both in ill health.