Two Cat setup??

[Dream240]

I've been doing some thinking on how to keep my car smog legal when it goes turbo now that I'm back in CA. I don't want to remove my exhaust or have to change the setup everytime I have to smog it.
I'm running with a Hotshot header, Random Tech. high-flow cat, and Apexi N1 dual. here's what I'm thinking:
I want to run the turbo setup with a T04 manifold and a 3"down pipe, but with 2 high flow cats back-to-back then the exhaust, thus making the downpipe a custom shorter piece.
1. Has anyone ever done this?
2. Would it help the car to pass smog?
3. How much would the setup increase back pressure?
4. Would this setup be ideal for my needs or just run the OEM cat setup along with the high flow cat?

Any info would be of help.

[hookedup240]

i don't know but Mustangs have 4 cats


Sorry i couldn't be of help

[misnomer]

You may want to see if it'll pass smog on a single cat. . .

Two cats is doable, it will increase backpressure (I'd definitely use two hi-flows)

[yudalicious]

I've never done it but.... just keep 1 high flow cat, it should be able to do all the cleaning, definitley don't need 2. the reason why the stock exhaust system had 2 was because in most 240s, the 2nd cat was a dummy cat (empty), or if it wans't empty (like my car), it was a cat that is not 3 way??? I think that's what you call it, meaning it does not "filter" all the dirty stuff in the exhaust.

BTW w/ your random tech cat, and htshot headers, did you get check engine light? I have a stock 2nd cat that is not 3 way and the 2nd o2 sensor was relocated behind so I still get a CEL.

[Dream240]

Originally posted by yudalicious
I've never done it but.... just keep 1 high flow cat, it should be able to do all the cleaning, definitley don't need 2. the reason why the stock exhaust system had 2 was because in most 240s, the 2nd cat was a dummy cat (empty), or if it wans't empty (like my car), it was a cat that is not 3 way??? I think that's what you call it, meaning it does not "filter" all the dirty stuff in the exhaust.

BTW w/ your random tech cat, and htshot headers, did you get check engine light? I have a stock 2nd cat that is not 3 way and the 2nd o2 sensor was relocated behind so I still get a CEL.

I did get a CEL when I first installed the header. I had to have a shop weld the O2 fitting Hotshot sells on their website and I extended the wires to reach it, reset the ECU and it was all good.
Runs great now.
I know what you're saying about the 2nd "fake" cat, someone once told me that it was a resonator, I think that's B.S.
I response to your problem, you'll need to remove that 2nd cat and put in an aftermarket cat, if you do go high-flow.
As far as testing my car's emissions, I figure with TWO aftermarket parts that are Off-Road-use-only(header and exhaust) there's no way it's gonna pass out here in CA. Another sign is the amount of exhaust coming out my pipes and the strength of the fumes. When I first bought the car the stock setup was very minimal on smell and fumes. Just an observation.

[yudalicious]

oh ok because I have the stock 2nd cat (which is not a sway cat) so I amg etting a CEL, so I am planning to get a aftermarket probably random tech. cat. I've already extended the O2 sensor behind the cat, so I'm all set.

Sorry I forgot they do visual eaxms in California. I am not familiar with visual exams in California, but what constitues an off read header vs. a road legal aftermarket header? If you use an ftermarket cat and have no CEL and have emission levels within standards, then shouldn't they pass you regardless of the visual exam?

[knightrider]

if your moving here to cali, it doesnt matter what your car puts out the tailpipe, if you cant pass visual, you wont pass period. and a turbo is not on the carb list of approved items. even hotshot headers wont let you pass. california is stupid, you could have the cleanest running car in the state, but if you have a aftermarket cone filter, you get your ass busted for no carb eo#. thats y im moving my registration to NV. hehe

[misnomer]

Knightrider: Don't let that get out!! I don't want all the auto owners from California following their businesses to my state :P

[knightrider]

sorry *zip* :|

[Dream240]

Originally posted by knightrider
if your moving here to cali, it doesnt matter what your car puts out the tailpipe, if you cant pass visual, you wont pass period. and a turbo is not on the carb list of approved items. even hotshot headers wont let you pass. california is stupid, you could have the cleanest running car in the state, but if you have a aftermarket cone filter, you get your ass busted for no carb eo#.

Yeah I figured that's what would happen with the visual test. But what about cars that come with stock turbo setups? Does the smogger know which cars come stock that way? In other words how is he to know if my car doesn't come in a turbo trim setup?
He probably has a book of some kind. Either way I'm keeping my car NM as long as possible!!

[knightrider]

when they scan the barcode thats on your door jamb, it has all of the car specs. like na or turbo, size of engine, how many cylrs, also all they have to do is look on the engine plate under your hood, plus i doubt your turbo setup is gonna look entirely stock, unless its SR20, which can look stock, just not for a USDM 240sx, esspecially when there are so many 240s out there owned by normal ppl with ka's they would notice a diference. sorry to burst your bubble

[Dream240]

Okay my bubble is burst. But tell me this if it's so illegal to have turbos and such, what is up with the new Edelbrock turbo kit for the Civic that Import tuner claimed was 50 state legal. If the visual laws are so strict, wouldn't this nullify the entire turbo setup alltogether? So what would be the point of making the turbo kit "legal" at all?
Does it have anything to do with the CARB stickers that are probably included with this kit?

Anyone have any ideas?

[knightrider]

if its 50 state legal, then they spent the money to convince the carb ppl that the emmissions equip is still intackt, which it prolly keeps egr and all that stuff, and yes it comes with a carb eo sticker it is posible to leagilize a turbo motor, you would have to do a bunch of work, but find your nearest referee, and ask him what it takes to make a custom turbo setup legal. referee's smog stations that are approved by the state to bust down on all the ricers. if you cant find your nearest referee, just ask a guy with a fixed up civic, he prolly has been there, all my friends have it will involve alota work, have fun

[Dream240]

When I finally get around to the turbo setup I'll check into that. Thanks!

[S14DB]

You could get some SS band clamps and attach the stock heatsheild on the Headers. that may hide it from a lazy inspector.

[Jeff240sx]

LOL! OR you could just swap back all the stuff. A turbo kit goes on and comes off in about an hour. Remove turbo, manifold, turn-down pipe. Drop the exhaust (PB Blaster and another hour) and replace with stock crap. Total of 4 hours extra work to switch from turbo -> stock -> back, which you only have to do once a year. That's how I'd do it, and why I'd never dream of owning an SR in Cali. Those swap owners over there are l33t outlaws.
-Jeff

[Var]

Originally posted by knightrider
when they scan the barcode thats on your door jamb, it has all of the car specs. like na or turbo, size of engine, how many cylrs, also all they have to do is look on the engine plate under your hood, plus i doubt your turbo setup is gonna look entirely stock, unless its SR20, which can look stock, just not for a USDM 240sx, esspecially when there are so many 240s out there owned by normal ppl with ka's they would notice a diference. sorry to burst your bubble

actually the barcode on the door only inputs the VIN number and no other info. The underhood label is what says all the specs. The smog tech determines required emission control equipment by reading the label.

edit: if you care dont buy a high flow cat. just get a normal universal one and take it out once you pass. High flow cats have caused many problems with cars that i've smogged personally. It works sometimes and not sometimes. I'm sure there are people on this forum who will tell you confusing stories about high-flow cats.