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Maranello 575 Tubi sound, but less loud , for free

Discussion in '456/550/575' started by AEHaas, Nov 15, 2003.

  1. AEHaas

    AEHaas Formula 3

    May 9, 2003
    1,350
    Osprey, Florida
    Full Name:
    Ali E. Haas
    I just set the bypass exhaust to stay open all the time. It normally only opens after the RPM gets over about 4,500. Now it sounds like a Tubi but about half as loud. The price equals zero. Perfect.

    aehaas
     
  2. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,270
    Switzerland (NW)
    How did you do it ?
    Is the mod applicable to a 550 ?
    Do you lose low end torque ?
    Comes awfully close to my "Tubi on demand" dream. If we could map this to a switch on the dash, it'd be perfect.
     
  3. Tim

    Tim Karting

    Nov 1, 2003
    88
    I am sure the car has a flat spot on the bottom end. you need that back preassure. the car would not be fun to drive like this until you overcome the flat bottom end. unless.....you drive your car for the sound only.
     
  4. AEHaas

    AEHaas Formula 3

    May 9, 2003
    1,350
    Osprey, Florida
    Full Name:
    Ali E. Haas
    Bear with me. I have read and researched the service manual for details. Although I have heard that the back pressure helps low end torque I have not seen this in writing. I was not anxious to try this for that reason but it is so easy to do and then reverse if you do not like it.

    There is a vacuum switch just behind the differential that goes to the exhaust bypass valves. Just pull the two hoses off and connect them together, that's it. Cover the openings to the switch to keep dirt out. To get it back to spec just reconnect the hoses to the switch. It is basically a 2 minute job with the car on the lift. Remove the plastic bottom cover from the transaxle for access. This should work for the 550 too,

    I only did this yesterday and was looking for any performance hits but cannot say it hurt anything. I will keep testing over the next week and give another report.

    When the engine is fully warmed up the note is a little louder than when the engine is cold, just started up. So far everybody says the sound is great, a good Ferrari note, loud enough but not too loud. The car itself is a quiet one so with the windows up the sound is no bother at all.

    It is interesting that you can put the car into 6th gear and idle at 700 RPM as you go down the road with your foot off the gas pedal. Try that in another sports car!

    aehaas
     
  5. Tim

    Tim Karting

    Nov 1, 2003
    88
    you can do the same thing on the 360. just disconnect the vaccume lines. if you have an F1 you definatly will NOT notice that the car has fallen on its face when you shift because with the F1 it falls on its face anyway. if you have the stick you will undoubtedly notice the loss of back preasure. and yes you can put it back. try and if you like it then keep it if not put it back. didnt cost anything and it does sound better.
     
  6. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,270
    Switzerland (NW)
    Tim, what do you mean by "falling on its face" ?
    Applicable to a 355 too ?
     
  7. AEHaas

    AEHaas Formula 3

    May 9, 2003
    1,350
    Osprey, Florida
    Full Name:
    Ali E. Haas
    I just talked with Adam Williams, tech dept at FNA. He told me that the exhaust rate is about the same at low RPM with or without the dampers closed. There is a little extra back pressure with closed dampers but this was to make the cats heat up faster, not for torque purposes.

    He told me there would be no effect on power / torque by bypassing the dampers but the cats would heat up slower. This would diminish the life of the cats. He did not think it would be a big difference in their life.

    The fuel mixture is rich at startup and raw fuel is one of the biggest enemies of catalytic converters.

    I thought I would use the extra, unused toggle switch on the central dash to actuate the bypass after the engine was warmed up. That would be the best approach. It would also be the legal one.

    aehaas
     
  8. 355f

    355f Formula Junior

    Nov 1, 2003
    305
    having had the benefit of dyno testing and a rolling road on 355 and 360
    jamming open the bypass valve is not a good idea at all.

    There is a substantial reduction in torque at the low end and the managamenet system tried to compensate as best it can for changed exhaust parameters.

    I think ferrrai knew a thing or two when they designed this system and not just for drive by noise regs either!!
     
  9. bobafett

    bobafett F1 Veteran

    Sep 28, 2002
    9,193
    FoSF guys actually recommended this method to me before they found out I went for CG. Said why bother with tubi...as Ali puts it, no loss in performance, no adverse effects, cheap sound fix which you can change back in no time.

    --Dan
     

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