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Lynn,
Very interesting, I hadn't seen this design before,
I would consider it simpler to manufacture than the first, therefore the
latest before the accident. I do like the design because of the simplicity - but
there are things I would change.
Correct me if I'm wrong, but it appears that their
mixing (cold air with exhaust ) within the muffler. I could be wrong
here as I can't see down the cold air tube and there doesn't appear to be
any/many air outlets for cooling within the outer jacket. I would only cool
using the outer jacket.
Secondly there is no tube from the inner exhaust housing feeding into the
main exhaust pipe. Of course there doesn't have to be, but to enable maximum
cooling air to evacuate (and mix with the exhaust within the exhaust pipe), a
low pressure area has to be created - it's what's
called exhaust augmentation in some designs, however in this design it's
probably more like cold air augmentation, whereas the exhaust is sucking in the
cold air.
Thirdly the use of cones at the ends
would help break up the sound waves - however it introduces complexity and
cost.
Overall not a bad design at all, I wonder if the
welds at the manifold broke. In this design there is the opportunity to
reinforce those joints with some flanges. Easy enough to do and the work is
hidden.
I wish I'd seen this design before I did mine.
there are a couple of ideas I would consider using.
George ( down under)
Ernest,
Copy you on that! What material type and thickness was the
Mistral muffler? Anyone know what their design was like? I know
that something fatigued and plugged the flow, but I never saw a drawing of
their muffler or had anyone explain how the failure actually occurred.
It could have been a baffle plate that was not well supported on all
sides. I don't see how that could happen to my muffler as the tube is
welded to both end plates and the exhaust gasses don't strike the tube
directly but swirl around it. Yes, a piece may fatigue over time and
crack off, but I can't imagine how it could plug up the exhaust path.
But I guess anything is possible if Murphy has his way. I'll keep a
close eye on it though. With a little finessing, I'm pretty sure I can
get my little inspection camera up the tailpipe. If that fails, I can
remove one of the O2 sensors and stick the camera through the hole for a peek
inside.
Mark
Here is one version of
the Mistral muffler. Said to be the failed version. Well thought out. Superb
exicution. Note that there appears to be a slip join in the main body between
the flanges. The whole muffler is encased in a cooling sleeve with a big
blast tube on one end and a coaxial exhaust areounf the down pipe.
My vote for the failure point is the flat disc closing the end
of the perf tube.
Nothing flat survives the pounding. If its
flat it dies. Round, conical or spherical, yes. Flat no.
Lynn E.
Hanover
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