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Screaming Cats on a hot tin roof
In a message dated 96-08-30 02:09:15 EDT, you write:
<< Well... It passwd on my dad's 84 Coupe with 190,000 miles,
my '84 5000 with 135,000 and my mom's 86 5000 at 160,000 miles.
Go figure, the coupe passed in Illinois and the 5000's were both
I was wrong about just hollowing it out, it WILL LOSE performance.
.... Coupla things.... 1) lots of new EPA testing equipment out there, and
Illinois now has some upgraded stuff.... The new equipment sniffs for a cat
in the tailpipe probe, if it exists, then the test is stopped at low idle
sniff only..... If it doesn't exist, and the visual shows a cat, it now asks
for the high idle test, hard to pass both with a tired motor, maybe a really
fresh one might (mine #2 didn't)....
2) J.C. Whinny sells a 3in in 3in out cat for low bux, hello Jeff.... Works
well enough, Jeff call me for some details on it...
3) A little misconception on empty cats.... The cat is the Biggest
restriction on the turbo audi exhausts, relieving that restriction, even with
no sleeve will reduce restriction.... What you do lose is directional
airflow, that is to say that the turbulence created by that chamber offsets
some of the loss of restriction, but no doubt pressure is dramatically
reduced...... The sleeve is a good idea, however, the point was made that a
pipe inside the chamber orifice is restriction.... I have seen some that
actually are opened up after insertion, but be advised that you cannot get
the opening all the way thru the chamber, so there is some restriction
there.... So, in essence the question becomes, does the turbulence of a non
restricted open cat offset the flow of a smaller sleeved chamber.... Me
thinks you will be close enough on either and certainly reduced pressure vs a
kitty on both, the best "dyno test" would be a separate test pipe..... Be
careful before you go drilling honeycombs, there are some strict laws that
may come to bite you in the **s for that trick.... And with the new
equipment the greenies have, it is almost impossible to empty the honeycombs
without getting busted.... Remember, I said almost....