Deleting secondary cats question | FerrariChat

Deleting secondary cats question

Discussion in '348/355' started by Shootfighter65, Jan 5, 2015.

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  1. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
    Full Name:
    Randy..alluneedtokno
    I just was told some guys or their shop takes a chisel and cuts the spot weld then removes the guts of the secondary cats. The reason is to use a remote bypass valve,wire it open or delete it completely. Running with the valve open can cause the cats to overheat and throw a cel. I'm not looking to get flamed on for not keeping my car completely stock it's my car.. But I do follow sound advise. Has anyone done this? Anyone have problems running a secondary cat delete pipe?
     
  2. INTMD8

    INTMD8 F1 Veteran
    Owner Silver Subscribed

    Jun 10, 2007
    6,748
    Lake Villa IL
    I opened up the stock y-pipe and removed the cats on my previous 99 GTS. No problems but I did keep the bypass valve functional.

    I think you would always get a cel on an OBD2 F355 as the post bypass thermocouple would always see exhaust heat.
     
  3. jochem00

    jochem00 Formula Junior

    Jun 19, 2014
    344
    Netherlands
    dont worry, the post thermocouple is even running cooler without cats.
     
  4. INTMD8

    INTMD8 F1 Veteran
    Owner Silver Subscribed

    Jun 10, 2007
    6,748
    Lake Villa IL
    Right but it's only looking to exceed temp threshold when it thinks the bypass is open. If bypass valve is wired open or deleted would that not set a code? I'm not sure.
     
  5. F355steve

    F355steve Formula 3

    Apr 9, 2008
    2,089
    Honolulu - Seattle - Okinawa
    Full Name:
    Steve
    Randy, removing the primary or secondary cats won't cause any problems beyond getting a CEL for the downstream o2 sensor. I (and many others) would argue that wiring the bypass valve open is what is dangerous to your engine.

    Remove the cats and keep the bypass valve and you are good to go. Also, drilling out the cats on the y-pipe is common.
     
  6. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
    4,425
    CT
    Full Name:
    Jay
    I gutted my secondary cats, tore them out and re-welded to close the hole up...then had them ceramic coated to keep the heat in. As already said no CEL, but yes need to keep the valve. Just use your right foot to keep it open ;)
     
  7. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
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    Randy..alluneedtokno
    Lol...I am getting a remote bypass from a Fchat member. I dont want to run it open all the time, but sometimes on city streets in evening its fun to be obnoxious. I have hyperflow cats and a Tubi. Hearing that sound reverberate off buildings in the evening is heaven to my ears
     
  8. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
    Full Name:
    Randy..alluneedtokno
    I wonder if using Hyper-flow cats and deleting the secondary cats will prolong header life...thats actually a question? Opinions? It has had Hyper-flows for quite awhile and at 40k the headers seem to be fine. I was thinking of replacing the headers but may keep running the stock ones if I can prolong their life
     
  9. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
    4,425
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    Jay
    Yes, removing restrictions and getting heat out faster should help prolong header life at least a little bit. I replaced headers with Fabspeed while doing the major...after I got them out I found that one side was almost burned through but had no outward symptoms yet.
     
  10. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
    Full Name:
    Randy..alluneedtokno
    How do you like the Fabspeed headers? I'm wary of them because of heat soak...I dont want to buy headers for 3k then have to dump another 1.5k into header blankets
     
  11. Fabspeed Motorsport

    Sponsor

    Feb 5, 2009
    3,134
    Fort Washington, PA
    Full Name:
    John S
    You won't have to worry about heat soak, we include a set of heat shields with our 355 headers along with offering ceramic coating services - if you are looking for additional protection. I PM'd you a little while back, not sure if you ever got it.
     
  12. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
    Full Name:
    Randy..alluneedtokno
    This maybe the way to go...do you always have them in stock ready to ship?
     
  13. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
    4,425
    CT
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    Jay
    Yes, I had my Fabspeeds coated locally to keep heat in and also attached some header wrap for a little extra insulation, looking great still after 6 years.
     
  14. jochem00

    jochem00 Formula Junior

    Jun 19, 2014
    344
    Netherlands
    wired open valve is not doing any harm to the engine either.
     
  15. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
    1,372
    Charleston SC
    Full Name:
    Randy..alluneedtokno
    It shouldn't. Anything after the O2 sensors shouldn't effect air fuel mixture.
     
  16. F355steve

    F355steve Formula 3

    Apr 9, 2008
    2,089
    Honolulu - Seattle - Okinawa
    Full Name:
    Steve
    There have been some detailed discussions about this on Fchat. Some very knowledgeable Ferrari people (techs/diy'er/keyboard warriors) have made convincing arguments against this.

    In short with a wired open bypass valve the exhaust takes the path of least resistance at low rpm's. The path is through the secondary pipes. That is not where the o2 sensors are. It can also suck air back up through the main pipes and further throw things off. This can cause ECU to detect extreme lean conditions and dump fuel into the engine. Cylinder was out, cylinder damage, spark plugs foul, misfires, cats getting destroyed.....

    Again, this is what has been argued in the past and please take the time to understand the potential side effects of wiring open your bypass valve.
     

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