Chippy
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| posted on 3/3/06 at 04:21 PM |
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Silencers again!
Can someone tell me what the effect of putting an expansion box before the silencer has. I am going to make a couple of silencers, 2' 3"
long x 6" dia. (repackable), but will have enough material left over to make a couple of boxes about 10 or 11" long. Expansion boxes would
be just a pipe in, and a pipe out, of an empty tube, am I correct?
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907
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| posted on 3/3/06 at 08:11 PM |
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Hi,
When I did some R & D on the size of cans I found that increasing the length
of the can had more effect than increasing the diameter.
In layman's terms, long and thin is better than short and fat.
Bends in the primaries help reduce noise as well, (a lot), and don't greatly affect flow.
Just my 2p
Paul G
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Chippy
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| posted on 3/3/06 at 10:20 PM |
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Hi Paul and Dave, what you have said is helpful, but what I really want to know is does fitting an expansion box help to make the exhaust less loud?
Anybody know?
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Volvorsport
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| posted on 3/3/06 at 10:32 PM |
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thats hard to say without a noise tester .
itll certainly get rid of the Boom .
www.dbsmotorsport.co.uk
getting dirty under a bus
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907
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| posted on 4/3/06 at 09:51 AM |
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I'm going to stick my neck out here and say, it will reduce sound levels. 
If I was making one I think I'd put a segment, cut from a bend, on the inlet and outlet, inside the box,
say 20 deg, so when you look through it you don't see a full circle, if you see what I mean.
For my Lotus engine I made the manifold from pipe, oval to round from the head, into bends, then into
a collector box, then bigger pipe, more bends, to the can.
The can is straight through, with sound reflecting ribs inside.
If it wasn't for the exit bend you could pass a 2" pipe right through it.
I'm very happy with it. Deep growl, like a V8, but relatively quiet, and no repacking. 
I'm sure it's the manifold, the bends, and c/box, that allows this though.
If the can was fitted to a 4 into 1 type front pipes it would be loud.
IMHO an exhaust system is just that, a system. Not pipes, with a can added on.
ATB
Paul G
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