[Shotimes] looking to buy a high flow cat

[Don McKinnon (AST)]

The list is getting so boring I thought I'd baffle everyone with BS!

Don McKinnon

-----Original Message-----
From: Ron Porter [mailto:ronporter@prodigy.net]
Sent: Tuesday, December 10, 2002 5:47 PM
To: Don McKinnon (AST); shotimes@autox.team.net
Subject: RE: [Shotimes] looking to buy a high flow cat


I'll be saving this post.

There are nights when I can't fall asleep, and I need something to read that
can help that!!  ;-)

Ron Porter

-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On Behalf Of Don McKinnon (AST)
Sent: Tuesday, December 10, 2002 5:20 PM
To: Rbade12@aol.com; 1badsho@thenuthouse.com; shotimes@autox.team.net
Subject: RE: [Shotimes] looking to buy a high flow cat


Here's some of my old exhaust research data diarrhea history!

I don't know what the internal cat substrates physical differences are of a
OEM cat vs. aftermarket "high flow" cat, but my understanding is that all
cat's today OEM are using monolithic cats.  I do know that the diameter (not
to mention routing!) of the inlet and outlet of the cat has a big effect on
the flow capability of a cat.  For instance the Carsound 23005 (2.25") flows
225 cfm at 13" H2O (301cfm at 18") where as the 23006 (2.5") flows 301 CFM
at 13" H2O.  BTW the 23005 is the cat that was used with the older SHO Shop
y-pipe, not sure about the new "equal length" version, the early pix that I
have of it shows a 4" round cat being used, perhaps the updated round cat
53005.  The 23005 has a 4" round body vs., the 94006 4"x6.5" oval body used
on the PP Y-pipe (that I had 3 years ago) so the frontal area of the
substrate is less (less backpressure).   The 94006 (2.5") flows 385 CFM at
14.5" H2O.  I don't know why Carsound has data at different H2O points for
their different cats!  Others have stated that these numbers are a reference
only as the exhaust flow is a pulse not a static flow.  I see now that
Carsound has a new version 9410x which is same 4x6.5 oval but uses a shorter
body length of 9" vs. 12" of the 9400x, sounds like a perfect cat for a SHO
Y-pipe with the tight spaces.

I was also told in the past that a stock cat flowed 185 cfm, BUT, the
pressure used was unknown.  John Holowczski mentioned that the factory
y-pipe was tested once and flowed 368 cfm at 28".  PP stated to me that the
flow rate at 28" H2O for the Cat'd Y-pipe was 541cfm and the catless pipe
was 546 cfm.  Sounds like "High Flow" to me!

A 2.25" pipe (as on the aftermarket y-pipes) calc's out to flow 457 cfm at
20" H2O, or using a conversion multiplier, 540 cfm at 28".  This matches up
pretty good with a 94006 who's converted CFM at 28" is ~530 CFM.   The
smaller 23005 converted would only get you ~340 CFM.  When I put on my PP
Y-pipe I mentioned to Ted B that my exhaust sound was very raspy.  I then
mentioned to him the flow that the PP y-pipe had per PP.  He adjusted my LPM
program as is done with the catless y-pipe program over the cat'd Y-pipe
program, worked perfectly!

I'm all booped out!

Don McKinnon
95 MTX - White/Mocha 89k miles
Stage 1 Power Package with Stage 1cams
Canyon Carver Road/Race Suspension
Quaife & HiRevs Competition Clutch


-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On Behalf Of Rbade12@aol.com
Sent: Tuesday, December 10, 2002 4:01 PM
To: 1badsho@thenuthouse.com; shotimes@autox.team.net
Subject: Re: [Shotimes] looking to buy a high flow cat


> Anyone on the list have  high flow cats preferably from Performance Plus
for
> sale ?
>

Try <A HREF="www.discountconverter.com">www.discountconverter.com</A>

I've had with friends, and I recall this list having, discussions about
wether there is such a thing as a "high flow cat". Seems to me, to do their
job they have to be restrictive. Can some of that restriction be engineered
out to allow higher flow yet still allow them to do their job? If that were
the case I'd think all cats would be manufactured high flow for no other
reason than having to put less stuff inside them, therefore reducing
manufacturing costs.

Does anyone have definitive high flow vs regular flow data?

Bob 93 MTX    PP Y-pipe with "high flow cats"
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