Looking at a 355 w/ bypass valve removed | FerrariChat
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Looking at a 355 w/ bypass valve removed

Discussion in '348/355' started by Targatime, Jul 18, 2014.

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  1. Targatime

    Targatime Formula 3

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    #1 Targatime, Jul 18, 2014
    Last edited by a moderator: Sep 7, 2017
  2. Eric C

    Eric C F1 World Champ
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    #2 Eric C, Jul 18, 2014
  3. Evan.Fiorentino

    Evan.Fiorentino F1 Rookie

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    #3 Evan.Fiorentino, Jul 18, 2014
    We saw a pretty significant loss in low end torque when we removed the valve.
     
  4. Dave rocks

    Dave rocks F1 World Champ
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    #4 Dave rocks, Jul 18, 2014
    Eric, you might want to revise those images and blank out the customer's name and telephone number...
     
  5. Dave rocks

    Dave rocks F1 World Champ
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    #5 Dave rocks, Jul 18, 2014
    If it has a challenge exhaust, It may not matter? My car has the bypass value but I have no muffler. IIRC, Dave Helms told me that the valve was still needed but I can't recall why.
     
  6. Eric C

    Eric C F1 World Champ
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    #6 Eric C, Jul 18, 2014
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  7. Eric C

    Eric C F1 World Champ
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    #7 Eric C, Jul 18, 2014
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  8. Eric C

    Eric C F1 World Champ
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    #8 Eric C, Jul 18, 2014
    Good catch. Thanks.
     
  9. Targatime

    Targatime Formula 3

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    #9 Targatime, Jul 18, 2014
    Thanks -- yes, had seen that previous thread Eric. Interestingly, the first service record image you posted indicating a few problem areas was not included in the records the current seller emailed me. Wonder why!

    But must say -- the previous thread on this car was unfair and included a lot of unfounded speculation. There was no respray done on the driver's door, and the compression numbers are normal (all cylinders are in the 190/200 range, with one at 185 and one at 210).

    This car had a couple of longer-term owners but has bounced around at various dealers over the past 3/4ths of a year. The below for sale ad (not the current seller) has some good pictures. I spoke to the shop that did the most recent service (compression test, etc) and the manager said the car was in very good condition and drove well. I haven't seen it in person.

    Elite Motor Group | Pre-owned Dealer | Phoenix,

    Still trying to understand what's up with the bypass valve.
     
  10. Eric C

    Eric C F1 World Champ
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    #10 Eric C, Jul 18, 2014
    Good Luck. I nearly bought that car until FCHAT scared me off.
     
  11. Targatime

    Targatime Formula 3

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    #11 Targatime, Jul 18, 2014
    Seems like a very important item.....

     
  12. F355steve

    F355steve Formula 3

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    #12 F355steve, Jul 18, 2014
    ^^^yes^^^ this is why you don't wire open you bypass valve either. This is why ferrari put a thermocouple right after the bypass valve to sense when it is and is not opening and a CEL will trigger if it is not opening and closing when it should.
     
  13. F355steve

    F355steve Formula 3

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    #13 F355steve, Jul 18, 2014
    If this is the car out of Portland that I am thinking of there is some infamous history attached to it. There was one in the color combo for sale off and on for 4-5 years (2007-2012?) via private party in portland. It was always priced really low and never sold. Finally someone on Fchat reported back after seeing it in person. Damage history and some rather obvious repair welds to the chassis where the doors met the fenders. If you are look at this one check for salvage history and have the car inspected by an expert for damage repair.
     
  14. Dave rocks

    Dave rocks F1 World Champ
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    #14 Dave rocks, Jul 18, 2014
    Last edited: Jul 18, 2014
    Guys, thanks for the education on the need for the bypass valve.
     
  15. White Knight

    White Knight Formula 3

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    #15 White Knight, Jul 18, 2014
    Agree, I learned something from this thread.
     
  16. Targatime

    Targatime Formula 3

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    #16 Targatime, Jul 18, 2014
    I would be surprised if this is the same car. The carfax is clean and as I understand the history, it was a two-owner car until recently that was not for sale until last year.
     
  17. Joe@Fabspeed

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    #17 Joe@Fabspeed, Jul 19, 2014
    This is joe at fabspeed Motorsport USA.

    Several years ago I made a cnc machined billet piece to replace the vacuum actuated exhaust valve that is on each and every Ferrari 355 . This was a fabspeed R&D project when we were dyno developing various exhaust and intake systems for the 355.

    The 355 OEM pierburg exhaust valve is located at the end of the 2ndary catalytic converters and directly connects to the top inlet of the 355 muffler. The valve is easily accessible.

    Once the machined top exhaust valve bypass piece was completed I installed it and drove the 355 spider. The 355 sounded great BUT felt very very lazy at low to high midrange RPMs. I drove the car for a while to let the ecu adjust. Nothing changed.

    Basically my butt dyno was telling me that something was very wrong. I reinstalled the stock valve and the car felt much stronger. Immediate change back to full power and the sportscar sound was of course lost at low to midrange rpm but restored when the valve opened as usual.

    I put the 355 on my chassis dyno and data logged it with and w/o valve. The 355 lost a ton of power all across the lower to higher midrange RPM band. The loss was so significant I aborted the product development on 355 2ndary exhaust valve bypass pipe.

    To get great power out of these Ferrari cars a set of headers, a set of HJS German sports 200 CPSI trimetalic sports race catalytic converters in conjunction with a sports race muffler from Tubi, Capristo, fabspeed or another brand really makes her sing!

    Moral of the story Leave the 355 exhaust valve in and if it is missing on a car purchase reinstall it you won't regret it.
     

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