Re: Muffler Madness

[Sean_Ford@idx.com]

To:   quattro
Jim,

This is all guesswork, and I'm sure the more technically advanced among us
will either correct me, or give a better explanation, but doesn't the cat
block a bit of the more noxious emissions when cold? I may be confusing
this process with another car, but I thought the cat held back some really
dirty stuff until it was warm and then let loose once it was able to better
clean up the exhaust. Anyone feel like spanking that theory?

Sean Ford           '92 Audi 100CS 5-spd 34k mi
Sean_Ford@idx.com        '98 Honda CR-V EX auto 0K mi
IDX,Boston,MA       http://www.geocities.com/MotorCity/Downs/5528


Original Message---------
Date: Thu, 12 Feb 1998 22:40:09 -0500
From: Jim Griffin <JGriff@pobox.com>
[snip]

I've noticed that on my Syncro (and as well on my 100 with V-6), that
when I first start the car and drive a bit, the exhaust is not nearly as
loud as when it gets going a bit down the road, until it starts to warm
up. Then, once it is "warmed up", it sounds noticeably louder/throatier.
In other words, it is almost as if all of a sudden, the engine/exhaust
finally "clears it throat", and starts breathing freely.
What sort of mechanical/scientific phenomenon is happening here?
Certainly there is some rational, scientific explanation for it. How
about it?
I am thinking that since the physical condition of the exhaust system is
not changing (ie. there are no mechanical flaps opening, pipe diameter
remains the same etc.), it must have something to do with the
characteristics of cool vs. hot exhaust gas (i.e. weight, density etc.).
Comments??
[snip]