Muffler Madness

[Jim Griffin <JGriff@pobox.com>]

Ok folks... here's one to ponder (and to get the bandwith off of
Mustangs... arghh!!).

First and foremost... there is no problem with either of my cars... this
is a tech question!!

(Keep in mind that I've put low-restriction exhausts on both cars...
although I don't think that it makes a difference relative to this
discussion. I believe it occurs in all applications... ie. OEM)

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??

(And don't tell me it is my imagination... I hear a big difference... if
you don't believe me... come for a drive... or listen closely the next
time you take your Mustang... oops... sorry, wrong list... Audi... for a
spin...)

--
                             Jim Griffin
                         JGriff@pobox.com
                    http://pobox.com/~jgriff
                          Maryland, USA
    "Perception is often stronger than reality!"
                        '92 Audi 100S
                   '87 VW Quantum Syncro
 ~~~~~~~~~~~~~~OOOO~~~~~~~~~~~~~~