Buy

f40 exhaust question

Discussion in '288GTO/F40/F50/Enzo/LaFerrari' started by bostonmini, Mar 16, 2004.

  1. bostonmini

    bostonmini Formula 3

    Nov 8, 2003
    1,881
    I know that clearly on the F40, there are dual exhausts, however there is one extra (3rd) central exhaust pipe..how does this work? what is it? what does it lead to?
     
  2. To remove this ad click here.

  3. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    Turbo Wastegate
     
  4. Dale

    Dale F1 Veteran

    Oct 7, 2003
    5,211
    uk
    Full Name:
    Dale Juan
    On turbo charged cars exhaust manifold pressure is higher than the inlet plenum pressure,youve heard the ricer pop off hiss during throttle off,
    same thing except the wastegate side(centre exh on F40)drops exhaust manifold pressure thus reducing boost,the flames are just HC'S unburnt fuel, it works well if you dont mind the extra heated engine bay,

    Dale.
     
  5. Robin

    Robin F1 Rookie

    Nov 1, 2003
    2,893
    Arlington, VA
    Thought I'd clarify here :)

    The wastegate regulates boost pressure by bleeding off exhaust gases from the exhaust manifold once it reaches a set amount of pressure. If your wastegate spring is set to 12psi, the wastegate opens above that amount and bleeds off excess pressure in order to prevent overboost, which happens when too must air is forced into the turbo, which then forces too much air into the intake manifold, which then blows things up...When the wastegate opens, it usually sounds like a small propellor airplane or loud farting sound. The air coming out of it is coming straight from the exhaust manifold, so it's completely unmuffled (although I think the F40 might have a resonator on the wastegate exhaust pipe).

    The 'ricer' sound you hear coming from the Supras, RX7s, turbo Civics, etc is the blow-off valve, aka compressor bypass valve, diverter valve, etc.. this valve fits between the intake manifold and the intake side of the turbo (the wastegate is on the exhaust manifold right before the turbo). The blow off valve relieves pressure on the intake manifold by opening up when the boost pressure drops to vacuum.. when accelerating, boost pressure builds up on the intake side, but during shifts or when you let off the gas, the throttle plates closes, trapping the compressed air in the intake plumbing, which then gets sucked back into the turbo. The blow off valve opens up to release this compressed air, preventing the turbo from sucking it back in.

    But yeah, the center pipe on an F40 is from the wastegate...

    -R
     
  6. bripab007

    bripab007 Rookie

    Feb 22, 2004
    36
    Thought I'd clarify a little more.

    Wastegates are not usually unmuffled on street cars. In fact, just about any turbo you're likely to see on a street car (unless it's a fairly high-end kit) has an integrated wastegate. This will actually just bleed off exhaust gases right into the downpipe aft of the turbo and is thus, muffled.

    Furthermore, early F40s had both the dual exhaust and the wastegate exhaust routed into a big, oval-shaped muffler. Perhaps all F40s had this oval muffler and this auction F40 has an aftermarket exhaust that routes the wastegate separately; I'm not entirely certain. But, if you go to www.ferrarina.com or www.ferrari.com to look at pics of the F40, you'll see the OEM muffler it came with.
     
  7. To remove this ad click here.

  8. tifosi69

    tifosi69 Formula 3

    Dec 23, 2003
    1,671
    Atlanta, Ga.
    Full Name:
    Al-Al Cool J
    F40s are the BADDEST IMO! I love to see the flames.
     
  9. F1racer

    F1racer F1 Rookie

    Oct 5, 2003
    4,749
    Laval
    Full Name:
    Jean
    #7 F1racer, Mar 16, 2004
    Last edited by a moderator: Sep 7, 2017
  10. Robin

    Robin F1 Rookie

    Nov 1, 2003
    2,893
    Arlington, VA
    Oops.. dunno what I was thinking. You're right, they're pretty much always routed back into the exhaust system downstream of the turbo. I was just thinking of some of the upgrade kits for certain cars where you can specify an 'open' wastegate that isn't routed back into the exhaust. You can tell when the wastegate opens up because of the loud tractor farting sound. Kinda cool if you're into that sort of thing...Thanks for the clarification.

    -R
     
  11. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    #9 dan360, Mar 16, 2004
    Last edited by a moderator: Sep 7, 2017
  12. To remove this ad click here.

Share This Page