328 air duct : advice needed

Discussion in 'Technical Q&A' started by F328GTS/GTB, Nov 17, 2005.

  1. F328GTS/GTB

    F328GTS/GTB Formula Junior

    May 3, 2005
    Full Name:
    #1 F328GTS/GTB, Nov 17, 2005
    Last edited by a moderator: Sep 7, 2017
    I found this picutre on a internet site (, but couldn't clearly understand what it is.

    It seems to be the air duct (left side in direction on the car), with a problem of material (fraying).

    I am looking to purchase a 1989 328 GTB, and would like to check this particular point before to purchase (among of course others more important..).

    I never heard about this air duct problem except on this internet site.

    Do any one of you have some kind of experience on 328 ?
    Any problem with air duct ?
    What do you think about the proposal of replacement by a 348 style duct ?

    Thanks a lot for your answers, and forza Ferrari !
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  3. Kingpin328

    Kingpin328 Formula Junior

    Nov 7, 2003
    Can't open link?! Don't know about the '89 airduct, nor about the 348-alternative, but in the pic it seems to be the insulation that has been rubbing against the inner mudguard. My '87 euro GTB, non-insulated, has a contact-patch in the same place, probably causing one of many misterious noises these cars will produce.

    I would focus on mechanical health, service history etc rather than this. Difficult not to love these cars. Best of luck!
  4. matteo

    matteo F1 World Champ

    Aug 1, 2002
    On a plane somewhere
    Full Name:
    Heir Butt
    my 78 and 83 308 had the same problem.
  5. F328GTS/GTB

    F328GTS/GTB Formula Junior

    May 3, 2005
    Full Name:
    Can you please describe the problem ?
  6. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    Houston, Texas
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    What he is calling ''fraying' is deterioration of the original fibreglass part....

    I've never known it to be a huge issue. You could easily repair the fibreglass and paint it....

    Detail workmanship on concealed parts has never been an Fcar priority. If it worked, it rolled out the door at Maranello.
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  8. Iain

    Iain F1 Rookie

    Jan 21, 2005
    The ducts are the same on both sides of the car - two moulded plastic ends joined with a kind of wire mesh ducting & then covered with a layer of foam with a smooth black finish - and they rub on stuff & the foam falls to bits. What you can see in that picture is not fibreglass, its the afforementioned foam rubber.

    Theoretically this would make the ducting of air to both the engine air intake and the oil cooler less efficient & they'll be dragging in air from the hot engine bay instead of (as well as) from outside the car.

    My solution for the moment has been two rolls of black duck tape!

    Interested as to where the fibreglass replacements might be sourced from
  9. Kingpin328

    Kingpin328 Formula Junior

    Nov 7, 2003
    #7 Kingpin328, Nov 17, 2005
    Last edited by a moderator: Sep 7, 2017
  10. wolftalk

    wolftalk Formula Junior

    Jan 27, 2004
    san franciso area
    Full Name:
    kingpin's pic is of the rigid ducting used on earlier cars. The 88.5 and 89 used the flexible duct.

    On my '89, I removed all the disintegrating foam. That leaves what is essentially a wire coil (like a slinky, if you remember what that is) with a mesh screen over it.

    As a first pass experiment, I just wrapped that in duct tape without any type of foam. The result is the higher noise level from the intake area, mostly when the exhaust air injection checkvalves are chattering before warm-up done.

    I'll probably take off the duct tape and wrap some high density foam around the coil/screen, then retape to see how much the noise is reduced. That would produce something similar to what the oem thing was.

    In any case, it's not a big deal. There's lots of ways to patch up the existing piece if concourse is not a concern.

    I haven't found any ducting that is equivalent from commercial suppliers.
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  12. Swissmondial

    Swissmondial Karting

    May 7, 2005
    I recently noticed a change in the noises coming from under the engine cover and felt differences in performance. On checking I found the foam on the air intake tubing had completely dis-integrated.
    My solution.....I cut the wire mesh out of the plastic end pieces and bought flexible aluminium tubing as used in tumble drier installations Hee Hee.
    Also, my theory, as the tube is completely sealed now, maybe there is some ram air at higher speeds. Cant tell really, as here in Switzerland it is too risky to put the pedal to the metal.

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