Exhaust mods and CA smog testing

[jjflash]

I live in L.A. and so I have some questions about cars with exhaust system modifcations so I don't get too interested in a car that is going to provide headaches passing CA smog emissions easily.

Questions:

Do "RMB" cars need to have anything put back on the car to pass CA emissions --assuming that everything else on the car is OK? Also on RMB, I've been told that this mod doesn't really affect smog certification at all.

Next, what about cars with "X-pipes?" I'm pretty these would fail the CA visual and probably the tailpipe emissions test--am I correct?

I don't have a real good idea of the quantifiable advantages/disadvantages of having either/both of these mods except from reading various vendors ads claiming extra HP and wonderful noises. I'm all for HP and a nice exhaust note, and if either/both of these are worthwhile, I wouldn't mind switching out every couple of years for smog. What I would not like is an exhaust "drone" at highway speeds that resonates in the cabin. Probably no way to determine this without comparing the stock exhaust with modded?

For a California car, seller is responsible for smog cert, and one seller said that he has the original catalytic converters for the car and would have these re-installed in order to pass smog. For out-of-state cars with this kind of mod I guess I would have to come up with suitable cats and have the work done myself.

Assuming I end up with such a car, is swapping an X-pipe for catalytic converters something that can be done relatively easily for semi-annual smog checks? If I ended up with such a car I'd have it smogged and then just swap the X-pipe back in immediately.

Thanks in advance for pointers.

[Danglerb]

So many shops have NEVER seen a 928, we often get cut some slack because they aren't sure about what they should be seeing. Full length headers on my 91 Mustang would not make it past the visual inspection more than maybe 10% of the time at BEST, but I don't know of any 928's that have failed due to headers, and I have seen more than a few.

Cat back is not smog related, just the normal do you have a muffler type inspection by Highway Patrol etc. so RMB is usually no issue as long as it isn't insanely loud.

Getting the sound "right" means a lot to me, more than plus or minus a few HP, so I am still fiddling a bit with my exhaust. I don't think outside of a track car the benefits of headers are worth the chance of failing an inspection or the increased heat in the engine compartment.

X or Y merge pipe and high flow modern cats have real torque and hp gains, so both are part of any planned exhaust for myself. Use OBD II style cats with a Carb EO# and inspection should go fine. Mufflers are a matter of personal taste, I like a single two or three chamber Magnaflow at the rear.

Thermal barrier coating is very appealing to me, so I am planning on factory 85/86 exhaust manifolds with JetHot extreme coating. I'm not sure on doing the merge (head pipes) yet mostly due to cost and chance I may redo the design again. Reducing under foot temps though sounds worth the money.

[sparky rowan]

I had a 1982 that was stock with the exception of the RMB. I never had any trouble passing smog here in SoCal. I now have a 1991 S-4 and when the only mod it had was the RMB, it passed smog with flying colors Since then, I have added the X-pipe w/o cats, and the performance chip and it will no longer pass emissions The RMB does sound much better then stock, and probably give a couple of more ponies

[jjflash]

Originally Posted by Danglerb

X or Y merge pipe and high flow modern cats have real torque and hp gains, so both are part of any planned exhaust for myself. Use OBD II style cats with a Carb EO# and inspection should go fine. Mufflers are a matter of personal taste, I like a single two or three chamber Magnaflow at the rear.

Would the original, stock cats, be OK? I don't know exactly what "OBD II style cats with a CARB EO #" are, but suspect this applies to aftermarket high-flow catalytic converters?

[Danglerb]

CARB is the California Air Resources Board, something like the EPA's state office or flunky, I'm not really sure, but they are the deciders on what is or isn't legal. If a vendor submits an item for testing and it works as well or better than the factory item it can get a Exemption Order number, EO#. As long as the cat on your car has a EO# appropriate for your car it will pass the visual inspection.

"Any" older looking cat might also pass the visual, but the law changed Jan 09 and now generic universal cats are not allowed "to be installed", only cats tested specifically for the vehicle with a EO# to prove it, may be legally installed.

Cars have to pass first the visual inspection, and then the sniffer test, fail on either, and you fail. Its a gotcha for the smog tech, since they must sign off that it passes visual, so if it fails the sniffer from something that should have failed in the visual, maybe they get inspected or something.

Factory cats are NOT high flow, they are old style air injection thermal reactors. Many are still good on 200k mile cars, but replace them with a modern design and you should pick up 5 or 10 hp and still be clean. The catch is that with some of the super high flow cats, running even a short time with a bad mixture can ruin them. I think there are reasonable choices that both flow pretty good, and last a long time. That said it may be hard to find a shop in Calif that is willing to install anything other than factory or Carb approved for that specific model.

85/86 928 had a wider intake, requiring a special air filter box and intake tubes, which are NLA, no longer available. People frequently fail inspection trying to work around using the factory air filter box or intake tubes.

[jjflash]

Originally Posted by Danglerb

Factory cats are NOT high flow, they are old style air injection thermal reactors. Many are still good on 200k mile cars, but replace them with a modern design and you should pick up 5 or 10 hp and still be clean. The catch is that with some of the super high flow cats, running even a short time with a bad mixture can ruin them. I think there are reasonable choices that both flow pretty good, and last a long time. That said it may be hard to find a shop in Calif that is willing to install anything other than factory or Carb approved for that specific model.

So swapping the original factory cats back into a car with an X-pipe will work fine. I don't know how much trouble it would be to do it yet.

85/86 928 had a wider intake, requiring a special air filter box and intake tubes, which are NLA, no longer available. People frequently fail inspection trying to work around using the factory air filter box or intake tubes.

They fail the visual, or the sniffer/emissions? That would be something to keep in mind if an '85 or '86 came up. I guess the safe way to go would be to buy a California car and make sure the seller does the smog.

Thanks for the clarification!

[Danglerb]

Originally Posted by jjflash

So swapping the original factory cats back into a car with an X-pipe will work fine. I don't know how much trouble it would be to do it yet.



They fail the visual, or the sniffer/emissions? That would be something to keep in mind if an '85 or '86 came up. I guess the safe way to go would be to buy a California car and make sure the seller does the smog.

Thanks for the clarification!

Some designs divide the exhaust into manifold, head pipe, cat, and cat back with a flange between each segment, but more typical is one flange between the manifold and head pipe with everything else welded. Dropping the whole welded exhaust head pipes to tail pipes is a common quick shop operation, like 15 minutes or so. Many keep the original stock, and swap if needed, but unless you use mess up the cat it should pass (new law is however untested).

Without a factory air intake or factory air box many have had their car fail the visual inspection. The catch is all sorts of tasks on the 928 begin with removing the air filter and tubes and over time they get more and more brittle.

[spiffcheese]

i dont no if this has been said yet but now with most x pipes you can have the x pipe on and the cats its one or the other but u can get hight flow cats that will do just about the same thing as the x pipe i live in northcal and the smog people up here know what there looking for on 928 witch sucks

[MPDano]

This is what I had put on my 928 a couple months back. In California, you MUST get a Cat that is Calif Approved and WILL have the numbers stamped in Big Legible Letters/Numbers. Any YES, they check with either a mirror on a stick or they get under there on a roller.

Magnaflow Part # 36037

Not sure if this is a Magnaflows High Flow Cat? Anyone know?

IDENTIFYING NEW AFTERMARKET CATALYTIC CONVERTERS
Catalytic Converter Labeling Picture

As of January 1st, 2009, what you need to look for to ensure you are selling, buying or installing California LEGAL catalytic converters:
The body should be clearly labeled with the following:

* A.R.B.- EO Number: (example: D-193-88)
* Part Number: (example: 34015)
* Date Code: (example: 0109)
* Directional Flow Arrow
* 1/2" Tall Numbers
* Must Be Visible From 5ft. Away

[devilinblack]

Originally Posted by MPDano

YES, they check with either a mirror on a stick or they get under there on a roller.

You need to start coming to the place around the corner from my house for your smog test. The guy asked if it was a 911, commented about all the smoke from the rear cam seal leaking onto the exhaust (and did nothing else) but it passed the sniffer test, and he got his $$ so all was good.

[jjflash]

Originally Posted by devilinblack

You need to start coming to the place around the corner from my house for your smog test. The guy asked if it was a 911, commented about all the smoke from the rear cam seal leaking onto the exhaust (and did nothing else) but it passed the sniffer test, and he got his $$ so all was good.

Send me his address!!

[jjflash]

Originally Posted by MPDano

This is what I had put on my 928 a couple months back. In California, you MUST get a Cat that is Calif Approved and WILL have the numbers stamped in Big Legible Letters/Numbers. Any YES, they check with either a mirror on a stick or they get under there on a roller.

Magnaflow Part # 36037

Not sure if this is a Magnaflows High Flow Cat? Anyone know?

It's getting clearer. . . . thanks for the pic!

I looked up the Magnaflow part you provided and it was $112.50! I'm surprised. I thought something like that would be much more expensive. The car I'm considering is an S4, though. So I would need TWO, right?

I tried to find the cost of an X-pipe, and the only one I could find was from 928 Int'l for $370 plus $60 shipping. They sell high-flow cats also, that apparently work WITH the X-pipe. Those are $400 for a pair.

The reason I'm asking is that I may have to deal with this in the near future--CA car with an X-pipe and original factory cats available. Original cats would have to be installed for smog and then question become whether to put X-pipe back on, or maybe put a high flow cat on in the first place and just let it be. I need to find out how much a good high-flow aftermarket cat would be.

Just to summarize so I know I'm thinking correctly:

FACTORY original cats are fine, assuming they are still working.

Depending on whether the X-pipe is flanged/bolted to the cat-back section of the exhaust, swapping them in-out is a more or less difficult job.

A high-flow, CARB-legal aftermarket cat is an alternative that eliminates any need for swapping AND could be installed with the X-pipe left in place?

An X-pipe might provide an extra 20-30 HP (???), while a high-flow cat will SAVE, what, another 5-6 (compared to stock cats) ???

Here are links to the 928 Motorsports page with THEIR X-pipe, hi-flow cat products. I don't think the X-pipe on the car I'm thinking about is from this vendor though....

http://www.928motorsports.com/parts/headerxpipe.php

and

http://www.928motorsports.com/parts/catalytic_converter.php

Well, I THOUGHT I was getting it clear....

Please don't ban me ;-).

[Danglerb]

Leo's cat is not "high flow", but I suspect its better flowing than the factory cat. Dual exhaust cars like the S4 use a pair of different style cats, different EO# with a canister shape.

All 928's react well to a more open exhaust, just making it a bit louder makes some owners happy.

Smog checks and what cats muffler places will install are still a bit up in the air. Even if I could get someplace to install it, I would not have a cat put on with an 09 date code unless the CARB EO# matched up to my car specifically. Investing in a couple old stock (pre 09 date code) cats might be a smart plan for the future, but I haven't done it yet.

I need cats good enough to fix any emissions issues, and I think that excludes the highest flowing cats like the Random Technology stuff. I also don't want anything drawing smog attention to my car, so the more legal the cats are the better I like it.

X or Y merge pipe, better flowing cats and muffler will enhance whatever the motor could do in factory trim, so gains for a 345 hp GTS will be a lot more than from a 234 hp early car, but all three on an S4 and 25 total rwhp gain seems typical.

Given the car you are looking at, I say LEAVE IT ALONE, drive it a few months before changing anything.

[jjflash]

Originally Posted by Danglerb

Given the car you are looking at, I say LEAVE IT ALONE, drive it a few months before changing anything.

I got some clarification from the owner of the car I'm considering on this. The car HAS the X-pipe with no cats and an RMB already installed. Seller has the factory cats stored and would return the car to stock condition for smog. Then I could reverse the procedure and put the stock stuff away until next smog check. Apparently nothing is welded up and it a matter of unbolting, bolting and putting the air pump back on.

So it appears that I could either drive it with the stock equipment OR put the X-pipe without cats back on, without a major hassle (no welding/cutting).

[MPDano]

If the PO had flanges put on the pipe to make for an easy exchange from X-Pipe no Cat to Cat, then that's cool as you have your smog sorted out. Is the car local to you? If so, when he smogs it, try and document the place and bring it back there for it's future smogs. Don't change a good thing. In between smogs, put the No-Cat set up back on and drive it like you stole it!

[MPDano]

Also, as soon as I get my car painted and all. I'm heading across the border (TJ) and get my "Y" pipe made and installed with flanges for an easy swap out.