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Question...CS and Pre-Cats

Discussion in '360/430' started by stinger, Apr 18, 2005.

  1. stinger

    stinger Karting

    Nov 3, 2003
    82
    San Carlos, CA
    I've searched through quite a previous few posts, but I haven't yet come across definitive answers to a few questions regarding pre-cats.

    1. Is it possible to remove the pre-cats from a CS (i.e. use 360 Challenge or European headers)?

    2. If you remove the pre-cats, will you definitely end up with the CEL coming on?

    3. Is it true that most exhaust emissions are removed by the pre-cats?...if so, I"m guessing going that route would definitely cause the car to fail a CA smog check.

    I'd love to be able to get the European exhaust sound while still running cats, I'm just not sure how much of a headache it would be to get there.

    Thanks in advance for any info.
     
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  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall
    If you go with the 99 or the Euro headers you will be eliminating the pre cats and picking up about 20 HP. It will still pass Ca smog test. There were some software changes done between those years so I will not promise that it will not set a CEL but I will say it is a 90% chance it will not.

    Ordinarily I am against such things but I currently have a 360 in the shop that had a failure of the precats and the motor ingested them. The motor is toast. I consider getting rid of 360 precats a positive environmental move. It will keep from turning 360's into raw material for Bud cans
     
  4. stinger

    stinger Karting

    Nov 3, 2003
    82
    San Carlos, CA
    I've never really been a big fan myself...from your experience it sounds like there could be good reason to be a bit afraid :-/ . I thought I remember seeing that the 360 Challenge headers were the same part number as the EU headers. If that is the case, I was wondering if they might bolt on to a CS and do away with the pre-cats.
     
  5. spyderman

    spyderman Formula 3

    Nov 4, 2003
    1,492
    Toronto - Canada
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    Spyderman
    You are saying the the main cats are just there for looks and that the pre cats are doing all the work? If that is the case then those who remove the main cats on the Stradale's (or post 99 360's) are not getting any benefit HP wise because the blockage (so too speak) is at the pre cats level. Interesting theory...
     
  6. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    "Ordinarily I am against such things but I currently have a 360 in the shop that had a failure of the precats and the motor ingested them. The motor is toast."

    Just curious as to how this could happen. In my 25+ years in the automotive technical field(primarily MBZ), I have never seen this on any vehicle.

    You can get as technical as you want as I have ASE mastertech certification and currently licensed to perform smog checks in the State of California.
     
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  8. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    1. Not saying that at all. Lots of cars have main and precats and both have and do a job.

    2. We do not know that. Both certainly cause some restriction but the cumulitive amount may be more than either by itself. I have not seen a test of that but I do know from experience that the precat does cause a noticeable HP loss.
     
  9. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
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    Brian Crall

    In a 2000 or newer 360 the precat is located in the collector of the exhaust manifold 22 inches from the exhaust port.

    If you have heard of reversion in an induction system the same set of conditions exist in the exhaust tract as well under certain engine operating conditions. A 360 has 69 degrees of time that the exhaust valves timing overlaps each other from one cylinder to another in the firing order of a given bank of cylinders. During that 69 degree period, again under some conditions some exchange of exhaust gas happens between cylinders and in that exhaust manifold the intersection of the primary tubes is the location of the broken, debris making cat core.

    If you don't believe me Nissan is recalling one of their cars for the same thing right now.
     
  10. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    No, I am not doubting you as I understand what you're saying. Ferraris are another animal of themselves.

    I can only presume that this may inherent to the design of the exhaust manifold in and of itself. Sounds like this should have been a factory recall.

    I have seen many broken, damaged, melted pre-cats in my day and many closer than 22 inches from an exhaust port but none had been ingested.

    I will utilize what you have informed me in my field investigations should a similar situation arrise.

    There have been a few damaged AMG engines which are still currently under investigation.
     
  11. 720

    720 F1 Rookie

    Jul 14, 2003
    2,623
    So. Cal and No. Utah
    Full Name:
    Rick
    i heard or read some where (maybe this is common knowledge??) that the reason the US version of the stradale has pre-cats is because the car has to pass certain smog tests when the engine is first started and is cold. apparently putting pre-cats in the headers is needed to pass this cold engine emission tests. apparently the euro cars are not held to this same standard so they do not need pre-cats. i also heard/read some where that the pre-cats are not necessary to pass the periodic smog tests. if this is true then you could replace the stock headers with 360 challenge headers (apparently the euro stradale uses challenge headers) and still pass the smog tests. assume for a minute that this is all correct (i definitely could be wrong), would be then have to reprogram the ECUs? it would seem that removing the pre-cats would require something be done to the ECUs???
    i bet matt at meridian would have some information ont hius topic? matt, you out there?
     
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  13. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,330
    SF, Bay Area
    I think it is worth while to say a couple of words about precats:

    1. They are primarily installed to reduce emissions at cold starts.
    2. When the main cats warm up precats operate in an open loop.
    3. Since they operate in open loop (Ferrari's poor design) if they start going bad as there is evidence they could, precat debris can get sucked into the motor and depending on the EGR system design debris could also find their into the intake tract.

    Edit: Because they operate in open loop there is no control signal sent/received to ECU. Taking them out will not trip OBDII warning signal.

    Here's NHTSA's recall regarding the engine damage by precats:

    [NHTSA Recall No. 03V067]
    Nissan North America, Inc.
    Models: Nissan Altima Year: 2002-2003
    Nissan Sentra Year: 2002
    Number Potentially Involved: 268,000
    Dates of Manufacture: August 2001 – February 2003
    Defect: On certain passenger vehicles equipped with 2.5-liter engines, the exhaust pipe hanger pin may catch debris from the road that could be ignited by contact with the main catalyst.
    Remedy: ... Also on 2002 Altima and Sentra vehicles, certain engine operating conditions may cause the pre-catalyst to overheat and damage the catalyst substrate. If substrate particles enter the combustion chamber, they could score the cylinder walls, resulting in increased oil consumption. If the engine oil level is not checked on a periodic basis and drops below the low level, and the driver continues to operate the vehicle ignoring noticeable engine noise, engine damage may occur that could result in a fire. Nissan is developing a remedy for the pre-catalyst problem.
     
  14. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall


    I agree that the manifold design would be a major player in the scenario.

    Recall? Time will tell.

    Which AMG motors and what kind of damage? Have a 99 E55 at home is that one?
     
  15. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    Assuming these damaged pre-cats caused the internal damage and if they are a 50 state/California (non grey market)vehicle, subsequent damage should be covered by the emissions warranty.

    Your E55 is safe. It was a few late model low mileage supercharged ones.
     
  16. udalmia

    udalmia Guest

    I asked my mechanic regding the pre-cat, he said the one on the US stradale is pretty small, the noise/hp gain is minimal and requires a lot of work (labor) to get rid of
     
  17. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
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    Brian Crall

    It is a Ca car and you are right it should be.
     
  18. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,330
    SF, Bay Area
    Were there any instances where the engine was torn up and inspected closely or any chemical analysis performed (on oil/carbon deposits) for wear material (platinum, palladium, rhodium?)
     
  19. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    I'm assuming you're an independent repair facility and more power to you if your clients trust you for the repair work and have deep pockets but I really think FNA should foot the bill, not your client.

    Again hoping you didn't tear it down too much for the inspection.
     
  20. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    When a catastrophic failure occurs, engines are not torn down and analyzed completely at the dealership level. Some basic checks are done but that is the extent of it.

    Engines are preliminarily inspected by a zone rep and 99.9% of the time. the engine is crated and sent back to the factory for the analysis. They wish to see the engine intact to reach their own conclusions.

    99.9% of the time, you will never have the final story.

    A replacement is sent, thats all.

    Factory Quote "zer iz nutzin vrong vit r carz"
     
  21. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall


    I am and I agree. We will see what we can do but more than that I will not say for now.
     
  22. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall



    What specifically happened to the AMG motors? I would be very interested to hear what you know.


    The car I am referring to is in the hands of the lawyers but I would sure like to know more about those Benz's. What sort of symptoms do they show?

    I'll show you mine if you show me yours. PM me if you like.
     
  23. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,330
    SF, Bay Area
    If I understand what you wrote correctly you never saw any debris being ingested into the motor after a precat failure because factory took over the inspection and they may or may have not found anything but they sent a new engine in a crate to replace the old one, is that correct?

    Earlier you had given an impression otherwise, from this quote:

    "...I have seen many broken, damaged, melted pre-cats in my day and many closer than 22 inches from an exhaust port but none had been ingested...."
     
  24. f430f1

    f430f1 Rookie

    Jan 28, 2005
    12
    Rifledriver and 4i2fly,

    I cannot say anymore in regards to the MB issue.

    Again, I did not/do not know the final conclusion(s).

    It was my mistake to bring up the subject.

    I apologize to all to whom this subject may have affected.
     
  25. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,330
    SF, Bay Area
    If you search the Internet you are bound to find data that shows this is a widespread problem with many makes and model, Subaru, Toyota MR2, MB, and Nissan to name a few that have had these issues with the precats. Others don't publish data because the risk of recalling thousands of cars to repair and replace components is just too high, until there is an investigation. While there is a good intention why a precat is used in an engine the systems are poorly designed to prevent catastrophic failures. There has been every precaution taken to preserve the main cats by OBD and almost zero efforts for the precats. If OBD has no idea precats are failing there is no slow down or limp mode or plain shut down associated with failure until it is too late. The issue then becomes, should one try to remove the precats from the engine before a potential catastrophic problem occurs?

    Aside from the increase in HP/Torque and the wonderful sound, I am with Rifledriver on this one and I would just remove the precats to have a piece of mind that in no circumstance the precat can play a role in damaging my engine.
     
  26. stinger

    stinger Karting

    Nov 3, 2003
    82
    San Carlos, CA
    I did a bit more investigating into the possibility of removing the pre-cats. From what I heard, the 360 Challenge and European headers share the same part number. At first I thought this would just work on a US Stradale, but then I was told that the Challenge headers don't have provisions for the air injection system (?)...apparently this would be a big deal to try and overcome.

    I tried finding an aftermarket company that sells replacement 360 headers without pre-cats, but hit a dead-end there as well. I guess Tubi never made them, and I was told that Novitec didn't have anything either.

    Apparently, the most feasible alternative would be to have the manifolds removed, gut out the pre-cats, then re-install them.

    Does this information I received sound accurate?
     
  27. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
    Full Name:
    Brian Crall

    It might be though I predict that this will become a problem in the not to distant future. I know Frank at Tubi style has been made aware of it. I think someone needs to convince him that we need an aftermarket manifold with air inj plumbing. The other alternative is to remove the air inj manifold from the existing manifold and have someone that is good with a TIG welder graft it on the 99/ euro manifold.

    You could do as you suggested but since getting involved in all of this I have not had a 99 or euro manifold off to make a comparison and at this point do not know if the primary tube length or collector design is similar. I suspect there are differences that were made to accomodate the precat. If so, doing what you suggest would solve one problem but may leave you with a manifold configuration that will not perform as well.
     
  28. stinger

    stinger Karting

    Nov 3, 2003
    82
    San Carlos, CA
    Thanks for the feedback Rifledriver.

    I guess until there's an aftermarket solution available with air injection plumbing, I have indeed hit a dead-end :-/ .
     

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