Regular CAT Converter VS. High Flow CAT. Is there a difference when it comes to smog? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Bukoone · 08-05-2007, 05:44 PM

Is there a difference when it comes to smog, especially in California? I Need to know because I need to pass smog, after I failed, and want to know whether it will still be okay to get a High Flow CAT, possibly a CATCO.

s13rookie · 08-05-2007, 07:21 PM

There are a lot of hi flow cats out there. Get one that is CARB cert'ed

SexPanda · 08-05-2007, 07:24 PM

Man its a shame most of you live in CA. I just gutten my friends SRT-4 cat. In MO, or at least this county, they just check to see if you have one. No smog, no emissions...

Go to autozone and pic up an OEM one. A high flow cat is high flow because it doesnt filter as well.

s13rookie · 08-05-2007, 07:32 PM

Quote:

Originally Posted by SexPanda

Go to autozone and pic up an OEM one. A high flow cat is high flow because it doesnt filter as well.

I must disaggree. An aftermarket air filter filters better and flows better than a stock one. I think materials and design have a lot to do with it

Also, I remember seeing a dyno a few years ago of a high flow cat versus a gutted cat. The high flow won by a couple hp, im not sure if it had to do with too little backpressure, or possibly turbulence

SexPanda · 08-05-2007, 07:36 PM

Quote:

Originally Posted by s13rookie

I must disaggree. An aftermarket air filter filters better and flows better than a stock one. I think materials and design have a lot to do with it

Also, I remember seeing a dyno a few years ago of a high flow cat versus a gutted cat. The high flow won by a couple hp, im not sure if it had to do with too little backpressure, or possibly turbulence

An air filter and a cat are 2 different things, and they work 2 different ways. Catalitic converts CONVERT harmful exhaust gasses into not-so-bad ones by the use of catalists. Think about it. High-flow cat has better airflow because the hnoycomb is bigger, meaning less surface area to convert harmful gasses, meaning better flow, but worse emmissions.

and i read an article about that too. It was against a test pipe, a stock cat and 2 high-flows. The best hi-flow lost 1 hp to a test pipe.

slamdbusa · 08-05-2007, 07:44 PM

High Flow cats do not convert the hydrocarbons as good as the OEM units, but in turn the OEM cats do not flow like the High Flow cats.

Bukoone · 08-05-2007, 09:03 PM

Quote:

Originally Posted by slamdbusa

High Flow cats do not convert the hydrocarbons as good as the OEM units, but in turn the OEM cats do not flow like the High Flow cats.

Yeah, and that's where my problem was... The Hydrocarbons (HC) were high. I have a stock CAT. The smog tech. told me that it was maybe bad, which is why I failed emissions. So I think I should stick with a OEM CAT instead of an aftermarket? Unless, anyone knows any good aftermarket CATs that has better performace and throws better emissions....

scarecrow27 · 08-05-2007, 09:28 PM

i use an oem cat to pass emissions then i rip that sucker off the second i pass and slap the test pipe back on.

bigOdom1 · 08-05-2007, 09:33 PM

id try a high flow cat and get it smogged while brand new

Ninjabread · 08-05-2007, 10:00 PM

Well, at this point, i'm sure a NEW highflow cat would perform better than your 15+ year old stocker. Plus you don't wanna upgrade twice.

240on430 · 08-06-2007, 01:20 AM

I would stick with a stock cat if you have a ca registered car.

Bukoone · 08-06-2007, 02:06 AM

alright thanks for the help guys! i think i know just what to do....please close this thread.

08-05-2007, 05:44 PM	#1
Bukoone BANNED Join Date: Sep 2005 Location: California Posts: 51 Trader Rating: (0) Feedback Score: 0 reviews	Close! Is there a difference when it comes to smog, especially in California? I Need to know because I need to pass smog, after I failed, and want to know whether it will still be okay to get a High Flow CAT, possibly a CATCO. Last edited by Bukoone; 08-06-2007 at 02:07 AM..

08-05-2007, 07:21 PM	#2
s13rookie Zilvia FREAK! Join Date: Mar 2002 Location: connecticut Age: 44 Posts: 1,129 Trader Rating: (0) Feedback Score: 0 reviews	There are a lot of hi flow cats out there. Get one that is CARB cert'ed __________________ Ive spent most of my money on cars and women...the rest i wasted

08-05-2007, 07:24 PM	#3
SexPanda Post Whore! Join Date: Jun 2007 Location: Where ever there is free beer Posts: 3,239 Trader Rating: (0) Feedback Score: 0 reviews	Man its a shame most of you live in CA. I just gutten my friends SRT-4 cat. In MO, or at least this county, they just check to see if you have one. No smog, no emissions... Go to autozone and pic up an OEM one. A high flow cat is high flow because it doesnt filter as well. __________________ BRAND NEW GReddy PRofec E-01 EBC for sale, Cheap!

08-05-2007, 07:44 PM	#6
slamdbusa Join Date: Jun 2007 Location: Texas Age: 55 Posts: 24 Trader Rating: (0) Feedback Score: 0 reviews	High Flow cats do not convert the hydrocarbons as good as the OEM units, but in turn the OEM cats do not flow like the High Flow cats. __________________ http://www.cardomain.com/ride/2510742

08-05-2007, 09:33 PM	#9
bigOdom1 Nissanaholic! Join Date: Nov 2005 Location: Auburn/Birmingham AL Age: 41 Posts: 1,817 Trader Rating: (4) Rides Gallery: bigOdom1 Feedback Score: 4 reviews	id try a high flow cat and get it smogged while brand new __________________ my car domain that good review thread

08-05-2007, 09:28 PM	#8
scarecrow27 Leaky Injector Join Date: Jul 2007 Location: New York Posts: 121 Trader Rating: (0) Feedback Score: 0 reviews	i use an oem cat to pass emissions then i rip that sucker off the second i pass and slap the test pipe back on.

08-05-2007, 10:00 PM	#10
Ninjabread Post Whore! Join Date: Jul 2005 Location: Ottawa, Ontario Age: 36 Posts: 3,492 Trader Rating: (2) Rides Gallery: Ninjabread Feedback Score: 2 reviews	Well, at this point, i'm sure a NEW highflow cat would perform better than your 15+ year old stocker. Plus you don't wanna upgrade twice. __________________ 613DriftWerks.ca

08-06-2007, 01:20 AM	#11
240on430 Zilvia Member Join Date: Nov 2006 Location: San Francisco Posts: 230 Trader Rating: (0) Feedback Score: 0 reviews	I would stick with a stock cat if you have a ca registered car.

08-06-2007, 02:06 AM	#12
Bukoone BANNED Join Date: Sep 2005 Location: California Posts: 51 Trader Rating: (0) Feedback Score: 0 reviews	alright thanks for the help guys! i think i know just what to do....please close this thread.