As mentioned in an earlier thread I have a non CARB legal supercharged car that I am trying to make California legal. I need to get both left and right cats. The factory cats are about $2000 for the pair. There seems to be quite a few aftermarket cats out there that are significantly cheaper. My car is supercharged, so I would assume that what's going out the engine is dirtier than a NA car. Passing smog and the sniffer test is my biggest concern. Should I break down and pay $2k for new OEM cats, or am I wasting money and just buy much less expensive after market? If so, which brand should I get? Thanks.
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Catalytic Converter Questions
- Thread starter 737driver
- Start date
Would be nice if you share what year your NSX is......
For example my CA legal cat: 1993 OBD-1 NSX is http://autoplicity.com/4984422-magn...g_2zy1mRp9VfFpT4SiGvK-D7LFpLK5W-nAaAsB28P8HAQ
You would need one for each side.
If you call up Summit racing they will beat that price since it's part of their policy.
Magnaflow makes the best from my experience.
For example my CA legal cat: 1993 OBD-1 NSX is http://autoplicity.com/4984422-magn...g_2zy1mRp9VfFpT4SiGvK-D7LFpLK5W-nAaAsB28P8HAQ
You would need one for each side.
If you call up Summit racing they will beat that price since it's part of their policy.
Magnaflow makes the best from my experience.
Well if he has a 2000+ NSX then all they do is hook up the OBD-2 WiFi Dongle - no sniffer and as long as there is no CEL then he is good.
it doesn't even do a diagnostic (to see if u messed with the software or anything to cheat).
it doesn't even do a diagnostic (to see if u messed with the software or anything to cheat).
My car is a 92.' I actually just found a pair of OE cats on craigslist from a 91.' The guy says that they only have 50 ish k miles on them. He wants $375 so this sounds like a good deal. My only concern is will they work well. I'm concerned with the supercharger and everything that I won't pass the sniffer test.
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The SC isn't as significant as the tune.
Make sure u do a pre-test so they can determine if u are going to be a gross polluter.
If u just test and u are a gross polluter that is registered with ur NSX forever and u may have to test EVERY year. In addition, u can no longer do the smog cheats since the readings are going to be way off and it may trigger a flag.
If u want to be even more creative, there are no laws that say that u can't add aftermarket cats after ur OEM cats. For example, put more cats where ur muffler is at. Obviously that would require some custom work.
https://www.facebook.com/groups/NorCalNSX/
Make sure u do a pre-test so they can determine if u are going to be a gross polluter.
If u just test and u are a gross polluter that is registered with ur NSX forever and u may have to test EVERY year. In addition, u can no longer do the smog cheats since the readings are going to be way off and it may trigger a flag.
If u want to be even more creative, there are no laws that say that u can't add aftermarket cats after ur OEM cats. For example, put more cats where ur muffler is at. Obviously that would require some custom work.
https://www.facebook.com/groups/NorCalNSX/
In order to make your car really "legal" in the state of CA, you'll need to bring your car to the CA BAR State Referee of smog. They'll thoroughly go through it and either give it a stamp/sticker of approval or deny you and recommend repairs.
I had to do this to get a JDM Integra motor road legal in a Civic. It basically is the smog check to end all smog checks. Took them like 3-4 hours. They go through everything and I mean everything...
I had to do this to get a JDM Integra motor road legal in a Civic. It basically is the smog check to end all smog checks. Took them like 3-4 hours. They go through everything and I mean everything...
I have 93k miles on my nsx. Around 40k miles boosted sc. I know my catalytic converter is tired and probably blown out. So you would recommend the magnaflow 336304. My concerns is how long the new catalytic converter will last with the supercharger. Part of me thinks all that extra pressure/boost is not good for the catalytic converter. I am on the 2.3L whipple also. I like RYU set up with the exhaust bypass at 4800 rpm. Any input is appreciated.
So my understanding of the emission laws as it pertains to cats is that u have to have either the OEM cat that matches the year and model of the car.
The aftermarket one like magnaflow option has to match the year and make/model of the car.
In both instances everything has to be in the stock location so there isn't any change of distance from the exhaust ports for maximum cat function relative to temps.
Technically you are not suppose to have any extra exhaust parts prior to the cat that isn't CARB EO blessed.
Now that being said, I haven't found a single law that says that you can't have additional cats after the OEM or aftermarket specific cat. More cats the cleaner the exhaust.
For my NSX I had STMPO custom make a full straight pipe that is modular and easy to swap out the cat for test pipes or magnaflow muffler. Only one of these can be on at any given time.
Cats are only on when I need to smog every 2 years.
The aftermarket one like magnaflow option has to match the year and make/model of the car.
In both instances everything has to be in the stock location so there isn't any change of distance from the exhaust ports for maximum cat function relative to temps.
Technically you are not suppose to have any extra exhaust parts prior to the cat that isn't CARB EO blessed.
Now that being said, I haven't found a single law that says that you can't have additional cats after the OEM or aftermarket specific cat. More cats the cleaner the exhaust.
For my NSX I had STMPO custom make a full straight pipe that is modular and easy to swap out the cat for test pipes or magnaflow muffler. Only one of these can be on at any given time.
Cats are only on when I need to smog every 2 years.
I am struggling with that idea a bit. It might not hurt; but, I don't see it helping for two reasons. First off, in order to do NOx control, the catalyst surface has to be hot (really hot). The catalyst gets hot from the temperature in the exhaust stream and from the conversion (combustion) of CO on the catalyst surface which also releases heat. In order for the CO to react on the catalyst surface there has to be excess Oxygen residing there. The excess oxygen resides there because the OEM ECU operates the fuel mix to tightly control AFR around 14.7; but, it continually oscillates around 14.7 providing periods of excess Oxygen to replenish Oxygen on the catalyst surface and facilitate the reaction on the catalyst.
A second add on converter will be impaired by low temperature in the exhaust gas and probably insufficient O2 to effectively deal with CO (and generate additional heat to help with the reduction of NOx).
Full disclosure - I am no catalyst chemist so my explanation probably strays from the full meal deal!
Are your headers ceramic coated and wrapped? that will help considerably.
