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How do I modify my chainsaw exhaust?

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Old 02-02-2009, 04:13 PM
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Default How do I modify my chainsaw exhaust?

Hey, I need some advice on how to sort out my exhaust.
Have a look [link=http://www.rcuniverse.com/forum/m_8418631/mpage_2/tm.htm]here[/link] and see what you think.

Please reply in that other thread.
Thanks











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Old 02-02-2009, 06:03 PM
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Default RE: How do I modify my chainsaw exhaust?

One of the things to consider as far as modding a pipe is of course the back pressure that you want returned to the exhaust port. Alot of this is dependent on the temperature and the speed of sound through the fluid medium (the exhaust gasses in this case), and when exactly you want the return pulse to come back for the given RPM range of the engine. Alot of this does entail fluid dynamics, and I dont even pretend to have a full grasp of this sort of thing, I am still studying it all.

To possible help you along, here are some on-line resources I found that might possible help you out

http://www.motorcycle.com/how-to/how...care-3423.html
http://en.wikipedia.org/wiki/Expansion_chamber
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Old 02-02-2009, 06:38 PM
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Default RE: How do I modify my chainsaw exhaust?

Thanks.
Interesting stuff there.

So basically, just putting a straight pipe, the same size all the way, is not such a good idea then?[]




Hmm.
Gonna have to do for now though until I get hold of something to make a chamber from.





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Old 02-02-2009, 06:44 PM
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Default RE: How do I modify my chainsaw exhaust?

A straight pipe will provide some back pressure, depending on its flow ability, but that back pressure would more or less be instantaneous instead of a proper returned pulse that expanding chamber exhaust systems give.

I dont know if you can rig it up, but somehow mounting your box-canister muffler will at least restore the stock back pressure. The tricky part will be figuring out the proper length of pipe to use so that you can clear the chassis and otehr bits and at the same time allow the box-canister to do its return pulses in proper timing.
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Old 02-02-2009, 08:42 PM
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Default RE: How do I modify my chainsaw exhaust?

Well, I butchered an old muffler which had the same holes for mounting and for the exhaust port.
I cut 2 pieces out of it, and have welded them together (badly) and am going to stick a pipe at the end of it.
This is only a temporary measure, and down the track I will probably look at getting one made up.
I know a dude who's a pro welder and he'd be able to make one up in no time.
He's one of those guys who works shiftwork though so I dont' see him that often.

Here's a drawing of what I'm making anyway.
It has a bit of a chamber so might give some compression.
Dunno.
I've kept the original muffler just so I can compare when I take the thing for its first run.


Thanks for the advice.











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Old 02-03-2009, 02:16 AM
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Default RE: How do I modify my chainsaw exhaust?

Boat guys use this

http://www.modelpowerboat.com/forum/...e-designer.htm

you got to measure a few things first

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