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De-catting a 360 ?

Discussion in '360/430' started by exiges, Mar 12, 2004.

  1. exiges

    exiges Karting

    Feb 26, 2004
    199
    Midlands
    Full Name:
    David Brown
    I've heard some guys here say they've removed the cats from their 360s.. I enquired at my local main dealer (while asking about a Tubi) and they'll de-cat the car for around £250 ($400)..

    To ring around for prices, I called Damax, who race-prepare 360s for the 360 Challenge series, and asked about Tubis etc.. and on the subject of de-catting they recommended against it.. saying it would do the engine management system no favours at all ..

    Anyone else looked into this ?
     
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  3. 355f

    355f Formula Junior

    Nov 1, 2003
    305
    Yes we have.

    I can speak for 355 with OBD11 not for 360 although the 360 is more advanced and more sensitive.

    Removing cats on later cars is not recommended. The fact is that cars from say 97 do not have cats that are restrictive and in the tests we did it was found that the computer did not substitute the optimum values as the second lamda sensor is giving the same reading as the first with a test pipe.

    If you did this on a Porsche 996 latest spec it would go to limp mode immediately. So the point is you simply dont know what the engine is doing. On my car for example it ran lean at high RPM, and rich mid stream.

    In all cases it will not give you more power in fact i might lose some - there is no advantge to removing the cats unless you like the sound it brings

    To do it properly you would need OBD11 replicators but not sure if anyone has done a good job of that!
     
  4. Buttuz4eva

    Buttuz4eva F1 Rookie
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    Dec 14, 2003
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    Challenge Farrelle
    So are you saying that replacing the cats with test pipes is a no no or replaceing the cats with straight pipes is a no no?
     
  5. 355f

    355f Formula Junior

    Nov 1, 2003
    305
    KEEP THE CATS
     
  6. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,064
    No, he is saying the process is a little more involved, in that you have to fake out the computer by using an oxygen sensor simulator. This device fools the computer into thinking the Cat is doing its job.

    The front oxygen sensor gives the computer information as to how much fuel to add or subtract from its "model". The back sensor tells the computer if the cat is treating the emissions into spec.
     
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  8. johnw

    johnw Formula Junior

    Jun 19, 2002
    438
    toronto
    Full Name:
    john
    do it. u won't regret it. the sound is UNREAL
     
  9. 355f

    355f Formula Junior

    Nov 1, 2003
    305

    its very noisy, no performance advantage and one does not know what the engine mangement system is doing. By removing them with no replicators one is doing somethng the engine management was not designed to do.

    Its your engine!
     
  10. bostonmini

    bostonmini Formula 3

    Nov 8, 2003
    1,881
    There is a performance advantage...2 actually 1) the noise will convince you you are going faster, thus you must really be...hehe, jk 2) seriously, a full exhaust (cat removal, headers, right back to the tips) will save weight! don't underestimate that...maybe up to 100 lbs.
     
  11. johnw

    johnw Formula Junior

    Jun 19, 2002
    438
    toronto
    Full Name:
    john
    i dont know why the engine would be effected by removing the cats. the ferrari dealer did my car and they didn't say it would effect anything adversely. in fact, i don't think they would do it if they thought it was going to cause problems.

    anyway, tubi test pipes and tubi exhaust makes for one wicked sound.
     
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  13. teak360

    teak360 F1 Veteran
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    Nov 3, 2003
    9,817
    Boulder, CO
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    Scott
    My 360 now has a Tubi and test pipes. It's too loud in my opinion, but does sound great at 8500 RPM through a tunnel. One advantage no one has mentioned is that the cats are big heat soaks and the 360's (especially the spiders) have a problem with engine compartments being too hot. Removing cats does help this problem.
     
  14. 355f

    355f Formula Junior

    Nov 1, 2003
    305
    I think its too load as well- but thats just my opinion. You also get a resonance at 2/3 K. The tubi is very nice when sceraming through a tunnel and if you use your f car not that often then its ok. If you actually do miles in it - thats another story.

    As to hat soak, actually if you use a thermo test there is not that much difference in underhood temps.
     
  15. Caruso360

    Caruso360 Karting

    May 1, 2003
    203
    Hey Teaky Weaky; they aren't loud enough!
     
  16. murph7355

    murph7355 Formula 3

    Nov 30, 2002
    1,691
    SE England Yorkie
    Full Name:
    Andy
    JohnW - is your car under warranty?

    The dealer may well have done it, but I do wonder what would happen if you had a warranty claim for something on the engine internals.

    It's not unheard of for people to have to fight to get claims covered under warranty on completely unmodified cars where the claim definitely relates to a fault. Let alone where quite hefty changes have been made (the exhaust is all part of the engine's respiratory system, and unless the brain [ecu] can cope with such changes, it must have an effect. These engines don't have the same levels of tolerance as a Nissan Micra).

    I would suggest that anyone with a current warranty obtained, in writing, that the warranty would not be affected with the modifications being made.

    If the car's not under warranty, going in with eyes open as to the potential costs of a failure would be wise.

    That said, I do like the sound of Tubi equipped cars. Pure F1. Whether you could live with it for 7k miles a year I'm not sure, but I'm sorely tempted to get a back box for my car :)

    Incidentally, my perception of US emissions regulations is that they are quite strict. Is running with no cats legal?
     
  17. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
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    Dave Helms
    Now this is shaping up to be the "Clash of the Titans". All I need now is a lawn chair and a Scotch...
     
  18. teak360

    teak360 F1 Veteran
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    Nov 3, 2003
    9,817
    Boulder, CO
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    Scott
    It doesn't rain that much here, so I don't worry about that.

    Seriously, what information do you have re: the cats and heat soak? I would like to know more about that.
    Thanks
     
  19. 355f

    355f Formula Junior

    Nov 1, 2003
    305
    Hi!!

    sorry about the spelling mistake!! its the small keyboard!!

    I can only support readings for the 355 which showed a 5% drop in temeratures in the engine bay. Not that significant unless one is running on the edge
     
  20. teak360

    teak360 F1 Veteran
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    Nov 3, 2003
    9,817
    Boulder, CO
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    Scott
    I try to always run on the edge.
     
  21. Buttuz4eva

    Buttuz4eva F1 Rookie
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    Dec 14, 2003
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    Challenge Farrelle
    who wants to sell there test pipes?
     
  22. johnw

    johnw Formula Junior

    Jun 19, 2002
    438
    toronto
    Full Name:
    john
    yes murph, it's an 02, still under warranty. i KNOW they wouldn't give me anything in writing but i think there is kind of an implied approval by them doing the work.
     
  23. brendon0

    brendon0 Formula Junior
    Silver Subscribed

    Dec 13, 2003
    600
    Tampa FL
    Full Name:
    Brendon
    http://www.o2simulator.com/

    Take the rear cats out, and slap one of these on there. Well, you may need two on a 360 right?

    It'll fool the computer into thinking the second cat is doing a dandy job.

    Enjoy.
     
  24. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,176
    socal
    The truth IMO is that you can take the cats out. When you lokk inside there is all this baffle and stuff. I cna guarantee there is a flow restriction and upset. That will cost you power. It may be little with the best cats but there is no way you can change physics. If you upset flow you upset power. That is what stuff like porting and polishing and port matching are all about. That said here is the deal OBDII cars. They have two oxygen sensors to measure the amount of oxygen contained in the exhaust gas. The first sensor is located upstream of the cats and measures O2 content of the exhaust to tell the ECU to calculate fuel/spark. The second oxygen sensor is located after the catalytic converter and is used only to detect the performance of the converter. The ECU does NOT use any data from the secondary O2 sensor for engine management. Thus the deal is the smog nazis have a second o2 sensor to trigger your check engine light or in some cars cause a limp home mode if the catalytic converter is removed. How is that for BIG BROTHER! That's why when people ask me about 355's with OBD1 or 2 I say buy OBD1. But hey... some people don't mind being strip searched at the airports.
     
  25. Buttuz4eva

    Buttuz4eva F1 Rookie
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    Dec 14, 2003
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    Challenge Farrelle
    With all that being said I would like to hear more on the testpipes is there a difference in tubi test pipes vs regular testpipes or is it jus the name .Also what about these silenced test pipes what are they all about I am pretty sure i want the tubi test pipes I dont have a problem with inspection due to friends nor loadness the loader the better but I dont want to loose that amazzing F car sound.
     
  26. sherpa23

    sherpa23 F1 Veteran
    Silver Subscribed Owner

    May 28, 2003
    9,501
    Colorado
    Full Name:
    Bastuna

    I'll bring the Scotch glasses...
     
  27. Dave

    Dave F1 Rookie

    Apr 15, 2001
    2,722
    Little Rock
    Full Name:
    David Jones
    "Now this is shaping up to be the "Clash of the Titans". All I need now is a lawn chair and a Scotch"

    Dave, you are so far off base with this statement!

    It should read, lawn chair & a Gin and Tonic...

    Of course 20 years ago it would have read,

    a bottle of Tequila and a good doobie.

    ;)

    By the way, my wife's cat turns 20 this year,
    do they make depends for small pets...
     

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