RE: Clogged cat?

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> > I have to affirm Ti's experience: I have had the cat on/cat off with
> several
> > cars to no noticable effect on power. 
> 
> Yah, me three.  I just removed an intact cat and swapped in a sleeved
> one and relaly noticed nothing at all.  Same sound, same power, or at
> 
While I too tend to prefer the cat installed ... it is the law after all
where I live ... to those of you who have run your engines with and without
the kitty have you sniffed the exhaust of the fully warmed up engine in each
configuration?  What you'll find is that the exhaust smells pretty clean
even w/o the cat ... especially as compared to the exhaust of the lightly
controlled emissions vehicles others have mentioned.  For the engine to be
able to run without burning up a cat the emissions has to be pretty good to
start with ... IMO the major benefit of the requirement of a cat.  

How many times have we seen posts of people who are able to get their car to
pass California emissions w/o a cat?  I know when I bought the QTC I assumed
it had one, but I didn't know for sure one way or another ... but when I
took it in to get smogged the first time the service adviser told me that
they were able to get the car to pass, but they tested the emissions at the
CO Tap Tube and they were the same as at the tailpipe and so they suspected
that the cat was hollowed (which I later confirmed).  

There are downsides to the cat as well ... the cat tends to produce SO2 ...
which when combined with the pools of liquid water in a cold exhaust system
creates sulfuric acid.  Wonder why you're seeing so many cars with SS
exhaust systems nowadays?  It is because they can tend to eat themselves
from the inside out.  I am also concerned about what happens when SO2 in the
air happens to come in contact with water in biological situations ...

Don't get me wrong ... I appreciate the improvements in air quality that
have come about as a result of more tightly controlling vehicle emissions
(as well as vapor recover nozzles on fuel pumps and smoking bans in
restaurants and public businesses for that matter) ... but I just wanted to
flip the coin over and remind all that it ain't just that mystical catalytic
converter that is giving us that clean air ...

... and to Huw ... don't just run out and find an old cat on an old car to
fill your needs ... it turns out that new catalytic converters in standard
form factors can be found at quite reasonable prices ... and provide less of
a flow restriction than an old cat removed from a wrecked car ...

Steve Buchholz
San Jose, CA (USA)