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exhaust pipe size and cat


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#1 icice9

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Posted 15 May 2013 - 04:23 PM

So my car is needs a new cat and I’m supposed to use a California legal cat. The cat that I’m supposed to use is the Magnaflow 36304 that has 2" dia inlet and outlets. But the problem is back in the day, I increased my pipes to 2.50" dia pipes. I want to use the Magnaflow 36026 cat , which has a 2.5" dia inlet and outlet. my question is, do I have to use the 36304 cat (that’s what’s suppose to be on my car) or can I use the 36026 cat with the larger inlet and outlet that will mate with my existing pipes?

 

 


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#2 rayaapp2

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Posted 15 May 2013 - 06:24 PM

The only thing that matters is the OBDII certification number that's laser etched onto the cats housing. You have that number and it will not be contested. Cat or pipe size doesnt matter. You can still retrofit universal cats to OEM specific applications so long as that number is in place for CA certification.


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#3 SuperDan

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Posted 17 May 2013 - 05:54 AM

The only thing that matters is the OBDII certification number that's laser etched onto the cats housing. You have that number and it will not be contested. Cat or pipe size doesnt matter. You can still retrofit universal cats to OEM specific applications so long as that number is in place for CA certification.

I did not know that. So I could put say a 3" exhaust system in and as long as I use a 3" universal cat that is CARB approved its all cool?


Experience is a hard teacher, she gives the test first and the lessons afterwards.

#4 icice9

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Posted 21 May 2013 - 06:30 AM

thank you soo much.


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#5 icice9

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Posted 28 May 2013 - 09:53 AM

So i tried to get my Cat installed this weekend and the muffler shop refused to install the 2.50" inlet /outlet cat (magnaflow 36026). They told me by law they can not install the cat unless it matched the part number that magnaflow states to use for my car (magnaflow 36304). so now i have to get the 36304 and have them install reducer fittings from 2.50 to 2.00 on the cat for it to work on my exhaust system. F**king California Emission laws!!!!!!!


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#6 rayaapp2

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Posted 28 May 2013 - 04:42 PM

As far as I understand the law, what you said is true. The last time I spoke with the BAR rep he stated any cat so long as its CARB approved is ok. It just has to have the serial numbers etched into it. Muffler shop might have wanted to sell you a cat or cover their own butts because they didnt understand the law. Or I could be miss-informed. If it were me Id weld it in myself. Universal Cats with CARB numbers are perfectly legal as far as the law goes as it has been transcribed to me by my BAR rep.

 

It use to be that you couldnt change the pipe in front of the cat at all without a CARB # or an OE part. The letter of the law has changed since then though. I suspect it still goes like that, but you can use a larger diameter universal... The best way of doing that would be to get the OE flanges from another Nissan as most of them use the same flange and cat for the older cars and use the OE style 3" ID cat... but not the 280z or non-turbo ZX... but say 280zxt and NX/sentra/240sx/300zx.etc all use the same flanges different pipe sizes to get that flange from and then use the flanges to mount your universal... It would not be contested with serial numbers and the need to use reducers is nullified.


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#7 SuperDan

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Posted 29 May 2013 - 12:27 PM

Universal Cats with CARB numbers are perfectly legal as far as the law goes as it has been transcribed to me by my BAR rep.

This seems to conflict with what magnaflow is saying on their website. http://www.magnaflow...4california.asp

 

 It is illegal in California to select a catalytic converter for installation based solely on vehicle weight, engine size, physical shape, size, configuration or pipe diameter.


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#8 Tony D

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Posted 31 May 2013 - 05:31 AM

Remember the lawyers when shops refuse to do things...
Plus, if you are selling things, you have money, and the state makes targets places where recovery of money is probable...
Misanthropic Anthroparion Class 5 Hoarder, aspiring to posthumous fame as my containers are cut open and the market floods with crap I've squirrelled away over the years! I endeavour to persevere...

#9 rayaapp2

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Posted 31 May 2013 - 06:39 AM

This seems to conflict with what magnaflow is saying on their website. http://www.magnaflow...4california.asp

 

 It is illegal in California to select a catalytic converter for installation based solely on vehicle weight, engine size, physical shape, size, configuration or pipe diameter.

 

 

Remember the lawyers when shops refuse to do things...
Plus, if you are selling things, you have money, and the state makes targets places where recovery of money is probable...

 

I think these two quotes go together nicely... NEVER AURGUE WITH THE BAR REP! His word is GOD! Even when your right... your wrong! So when he says something I do not question, I make note(with his information) for reference in case if any state agency every comes for an audit...


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#10 HowlerMonkey

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Posted 04 June 2013 - 05:57 PM

Call up magnaflow and let them know that they would sell more product if they could get approval for larger diameter pipes in addition the the ones recommended for the application.

 

They might simply get approval for the larger diameter.



#11 Tony D

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Posted 29 June 2013 - 12:37 AM

Ray pretty much covers it. What the BAR says goes. Unaccountable and uncontestable. It's an interesting setup of collusion between federal legislators and local legislators, making an organization ostensibly for the public good, but above the law in many ways, unaccountable to the electorate.

 

I fit EVERY requirement they made for my 73 to do a Pre-May 1984 Engine Swap (70 Engine in it), and in the end the BAR guy got on the phone, and said "NOPE" and that was that. I retorted the next time he saw me it would have an LS3 454 in it (this was 1991, btw...foreshadowning in a scary way!) and his response was a cheery "Oh we can smog THAT!"

 

From that point onwards, until January 2013 I did not legally smog a single one of my vehicles. I was pressed  for time in January, and couldn't take the time to play around.

 

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#12 stupid_fast

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Posted 02 August 2013 - 09:05 AM

When I was collecting parts for my ZX turbo swap, I ordered a magnaflow 36757 direct fit cat for my exhaust-  So basically these 2" are the ONLY cat I can legally run?

 

Is there any point in going with a turbo back  3" exhaust because of this ?

 

 Thanks. 


Edited by stupid_fast, 02 August 2013 - 09:05 AM.

83 ZX NA->L28ET


#13 randy 77zt

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Posted 08 August 2013 - 03:20 PM

I had 2 exhaust systems that would bolt to the flange on the stock 280zxt downpipe.1 with a cat and 1 with a muffler where the cat was.



#14 Gollum

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Posted 12 August 2013 - 07:41 PM

I think a bit of the issue here on this topic is that comapnies like magnaflow have to cover their butt, big-time. Laws in CA seem to change on a quarterly basis.

As far as I know, the BAR Rep that ray talked to was probably speaking more to the process than anything else. The station attendants want to have a CA-specific serial to enter. That matters MUCH more than being vehicle specific.

And of course, the local ref is the law, so ask him if ever in doubt. Last ref I talked to told me to put a LS1 in my ZX... they're not bad people generally.

Personally I'd just do it myself. A cute little welder from harbor freight is plenty for doing small exhaust jobs like this, and will save you a lot of money in the long run. Then you've got your 2.5" in/out cat and a serial number to satisfy the law.

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#15 9rider

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Posted 09 October 2013 - 04:27 PM

I drove by a check point - smog only on San Gabriel Blvd , Los Angeles sub. They stopped all pre 2000 cars and smog test it on site. It was pretty scary. 


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#16 johnc

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Posted 10 October 2013 - 05:14 AM

You do not have to stop at one of those checkpoints.


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#17 jkgts1

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Posted 30 November 2013 - 06:03 PM

You do not have to stop at one of those checkpoints.

If we have a pre 75 smog exempt car we dont need to stop at those check points?


Edited by jkgts1, 30 November 2013 - 06:04 PM.


#18 johnc

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Posted 01 December 2013 - 07:14 AM

No you do not. It's voluntary. They will pressure you but just ask the officer if you are under arrest. If he says no then ask him if you are free to go. He will argue a bit but just keep asking that question. Works at sobriety checkpoints too.
----- John Coffey, Fabricator at Benton Performance, LLC

#19 Tony D

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Posted 03 December 2013 - 03:35 AM

And to reiterate, your pre-76 Z-Car IS NOT Smog "Exempt"!


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#20 stupid_fast

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Posted 14 June 2015 - 09:16 PM

Figured it out, talked to a smog tech who's into datsuns...

The catalytic converter just has to have a matching california EO number, this is the only thing the smog tech is required to put into the computer or check through their processes. 

 

Lots of model catalytic converters have the same part number.

 

I put a certain 3" cat on with the correct EO number and passed inspection no problem.   A BAR ref might catch this, however.  A normal smog tech if he dies it by the book and knows his pre-96 laws will pass it.  Most techs in my area took one look at the L28ET and say 'you need a BAR label' ... 

 

Also, the downpipe and section up to the catalytic converter must remain stock as well. 


Edited by stupid_fast, 14 June 2015 - 09:18 PM.

83 ZX NA->L28ET





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