Re: mufflers

[Steve Stegmann <stegmann@domain.elided>]

Rick,

How can the simple straight through glass pack be a poor flowing muffler? 
I've done a lot of flow work and I just don't see how this could be.  All
the other mufflers I've seen (& cut, or blow open) cause the flow to come
compleley out of the tube, change direction in a chamber and then go back
into the pipe to get out.  Some go through this severaltimes to get it
really quiet.  Not sure what they do in a turbo, but I would bet $20 it is
pretty much some variation on this theme if you cut one open.  From what I
can guess, they minimize the restriction and use a large pipe. 

When you jerk the flow around like this, you are restricting the flow,
according to every flow loss calculation I've ever seen, and I've seen a
bunch over the years.  Rapid direction change, rapid change in the 
flow diameter, and entry & *exit* from a pipe are your big enemies in 
flow loss work.

If you want to use the shock waves in the exhaust for scavenging that is
done in the header (or header/megaphone on motorcycle,or racing chainsaw
[boy are these extreme, they ony have one rpm]).  I believe most headers
do this.  But, this is really tuned to a fairly small rpm band (as is the
ram intake manifold on the old Dodges, and new Ford V6's in the Contour
and Windstar), and usually high.  This is why most headers don't change
the power of a low rpm engine like an IH. 

Has anyone ever seen a comparison of the Turbo's against a clean glass 
pack?  All the tests I've seen are aginast factory mufflers, which are 
designed against noise abatement standards.

One of the problems with getting old is that mostly when you see "NEW and
IMPROVED!!!!!"  you say, Oh yeah!  So and So tried that back in '09 and it
didn't really make much difference.  This drives my son (he's 21)
absolutely bats!!  John, ever have this happen?? 

Sorry for the rant!  I apologise.  Happens every week and you guys were 
the lucky ones this week.

Steve

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Steven A. Stegmann
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