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360: Disconnecting exhaust by-pass

Discussion in 'Technical Q&A' started by raygr, Feb 13, 2004.

  1. raygr

    raygr Karting

    Nov 1, 2003
    128
    Seattle Area
    Full Name:
    Ray
    Just for kicks, I disconnected the stock exhaust by-pass valves in my 360 spider, yielding a more robust idle tone, and more gusto during low rpm acceleration. Has anybody else tried this? Does anyone know if it hurts performance?

    Btw, it was easy; I disconnected the electrical connectors from the vaccuum switches.
     
  2. raygr

    raygr Karting

    Nov 1, 2003
    128
    Seattle Area
    Full Name:
    Ray
    Update: I've put a hundred miles or so on the 360 with the exhaust by-pass valves held open. Verdict: sounds great! More bass at idle, more exciting low speed sound, and no resonance. It's not all that loud either. Let me know if you want instructions.
     
  3. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Please PM me the instructions.
     
  4. docapl

    docapl Formula Junior
    Silver Subscribed

    Apr 26, 2002
    260
    SF Bay Area
    Full Name:
    Anthony

    Please send me a PM with the instructions. I would like to give it a try too.
     
  5. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Did it last night, oboy, imagine my smile as I heard what was close to my ex 348 tubi sounds coming from my 360, fantastic. Disconnected the leads (all of 30 seconds work) started her up and hey hey, thats sounds better. Shut car off, reconnected and started her up again - oh dear, just another muted engine. No guesses what mode I will be driving around with this weekend. I hear that Porsches have an option for an inboard switch do do this on the fly - hmmm methinks this might be an idea.
     
  6. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Forgot to thanks Ray for this - Thanks BUD!!!
     
  7. ninja_eli

    ninja_eli Karting

    Nov 1, 2003
    71
    London
    Full Name:
    Ali
    Hey guys,

    please pm me with the instructions too!!!


    thanks in advance,
     
  8. 360

    360 Karting

    Feb 27, 2004
    127
    Orpington Kent
    Full Name:
    Chris M
    Please EM the instructions to me also
     
  9. MarkCollins

    MarkCollins F1 Rookie
    Owner

    Jul 2, 2002
    3,198
    South England
    Full Name:
    Mark Collins
    Interesting, it must work in reverse to the 355 which is closed until the vacuum control is opened by the solenoid wheras the suggestion is that by removing the wires it stops the solenoid thus leaving the valve open. I can't believe it would do any damage, it's just there to meet driveby noise regulations (at least for Europe), i had to wire my 355 open last year when the valve failed and it sounded much better and I still believe pulls better as well

    My P4 replica project has a pair of 360 valves diverting the exhaust to straight through pipes with a dash mounted switch to open/close them :)
     
  10. tracknut

    tracknut Rookie

    Nov 1, 2003
    31
    Folsom, CA
    Full Name:
    Dave Mills
    Let's see the instructions - sounds like fun!

    Thanks
    Dave
     
  11. Diablo

    Diablo Formula Junior

    Does not hurt performance, but just watch your cat temp...

    Price to pay for extra noise.....thousands(when you can't pass emissions)

    You should just wire the by-pass open if anything.
     
  12. docapl

    docapl Formula Junior
    Silver Subscribed

    Apr 26, 2002
    260
    SF Bay Area
    Full Name:
    Anthony
    Vaughan,

    For some reason I can only find the connector on the right side, not the one on the left. What year is your car ? Did you find one or two connectors ? Assuming it is a single valve in the muffler flap, why would there be 2 anyway ?

    Thanks
     
  13. Caruso360

    Caruso360 Karting

    May 1, 2003
    203
    The way a 360 was meant to sound is to remove the cats and that 900 lb stock muffler, replace with bypass pipes and a Tubi. Your engine will appreciate it!
     
  14. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Will post some pics tomorrow, there are two, one for each side as each side has a valve. Can only do the car good as it breathes easier!!
     
  15. docapl

    docapl Formula Junior
    Silver Subscribed

    Apr 26, 2002
    260
    SF Bay Area
    Full Name:
    Anthony
    Thanks. It would be great to see the picture of the one on the left side.
     
  16. Ade

    Ade Formula 3

    Jan 31, 2004
    2,095
    UK
    Hey Mark,
    I'd quite like to try this on my '97 355, to see how it sounds. Do you have any instructions on how to do this on a 355? Is it easy?

    I've already got a Tubi, but my cats are still on (they might be coming off in a couple of weeks after MOT).

    Thanks
    Adrian
     
  17. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Ok here are the pics, the blu arrow is the connector that is now unplugged and the Amber arrow is the valve solenoid or whatever that controls the exhaust valve in the muffler. The first pic is the left connector as your facing the engine.
     
  18. vanimal

    vanimal Formula Junior

    Mar 19, 2003
    380
    UK
    Full Name:
    Vaughan
    Question to those in the know, should I cover up the loose connectors to prevent water from getting on the connections??
     
  19. tracknut

    tracknut Rookie

    Nov 1, 2003
    31
    Folsom, CA
    Full Name:
    Dave Mills
    I'd cover them....

    I'm not clear on those pics - do I need to pull off the muffler to get to the solenoids? Or go in from the bottom?

    Thanks
    Dave
     
  20. mbarr

    mbarr Karting

    Jan 11, 2004
    220
    How does this increase cat temps?
     
  21. docapl

    docapl Formula Junior
    Silver Subscribed

    Apr 26, 2002
    260
    SF Bay Area
    Full Name:
    Anthony
    Vaughan,

    Found the connector. Thank you for the pictures.

    I cant wait to give it a try !!!
     
  22. raygr

    raygr Karting

    Nov 1, 2003
    128
    Seattle Area
    Full Name:
    Ray
    Here are the instructions again:

    1. Open the engine lid. On the spider, remove the two access panels on the sides at the rear. You'll need a metric #4 allen wrench (or a 5/32" allen wrench).

    2. On the coupe, look directly to the left and right of the muffler. On the spider, look under each panel you removed. There is an electrical connector attached to a gray or white plastic block; the block is a vacuum switch. If you look closely, there is a black hose that goes from the vacuum switch to a vacuum can which operates the exhaust flap.

    3. Disconnect the electrical connector by pressing on the underside of it while pulling it out. You might want to twist-tie it to something to keep it from flopping around. Btw, you can disconnect and reconnect this with the motor running to hear the sound difference.

    The one on the right side (passenger side) is easier to reach because the left side has an electric air pump mounted in there. (At least on my spider there is.) I didn't disconnect the vacuum line itself because the left side was too difficult to get to. All you need to do is disconnect the electrical connector at the vacuum switch.

    4. On the spider, replace the access panels. Be careful not to drop the screws or washers down below because they will get trapped in there. You might want to use a towel over the muffler area.

    That's it! Enjoy,

    -Ray
     
  23. raygr

    raygr Karting

    Nov 1, 2003
    128
    Seattle Area
    Full Name:
    Ray
    I don't see how it affects the cats, since the by-pass is downstream from the cats. It should be the same volume of gas passing through them.
     
  24. docapl

    docapl Formula Junior
    Silver Subscribed

    Apr 26, 2002
    260
    SF Bay Area
    Full Name:
    Anthony
    Thanks for posting this information. Here is me experience:

    I tried the exhaust flap bypass mod today and must agree that the exhaust note at idle sounds really fantastic. BUT, I do think that there is a loss of low RPM torque with this arrangement. It is most noticible when accelerating from 60 mph in 6th gear without downshifting. I would like to dyno or do timed acceleration runs to be sure, but I really do think it must be a significant loss of torque for me to notice it. Maybe the ECU will re-learn and things will improve ? I dont know. Above about 3500 rpm everything is fine. Also, once the car is moving, the induction sound is still louder than the exhaust so the sound is improvement is only noticed at very low rpm.

    Do Tubi or Capristo have these issues ?? I dont think they have a flap/valve.
     
  25. tracknut

    tracknut Rookie

    Nov 1, 2003
    31
    Folsom, CA
    Full Name:
    Dave Mills
    Thanks for the description Ray - easy enough. Sounds great in the garage, I'll need to get out and drive it!

    Dave
     

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