1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

lifting the back of the bonnet to let hot air out

Discussion in 'A3/S3 Forum (8L Chassis)' started by harvey01, Mar 19, 2013.

  1. harvey01

    harvey01 Member

    Joined:
    Dec 13, 2011
    Messages:
    523
    Likes Received:
    9
    hi all has anyone lifted the back of there bonnet to let hot air out as ive done it with a few of my past cars but not shore with the s3. But as the turbo is at the back of the bay it should work ok
     
  2. Advert Guest Advertisement


  3. James TQ

    James TQ Member

    Joined:
    Apr 20, 2012
    Messages:
    564
    Likes Received:
    7
    it catches on the wing and takes paint off
     
  4. 16Klappe

    16Klappe I <3 Panda's!
    Supporter

    Joined:
    Sep 16, 2008
    Messages:
    5,796
    Likes Received:
    1,182
    Just no.
     
  5. StaceyS3

    StaceyS3 Well-Known Member

    Joined:
    Dec 17, 2010
    Messages:
    2,455
    Likes Received:
    429
    Just take the rubber sealing strip off that will let plenty of hot air out if that's what your after ;)
     
  6. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow...
    Staff Member Moderator Audi S3

    Joined:
    Sep 14, 2008
    Messages:
    19,941
    Likes Received:
    3,276
    Just be aware that removing the rubber and/or lifting the bonnet at the back allows water to enter the back of the engine bay... have seen corrosion etc as a result

    <tuffty/>
     
  7. Lemon S3

    Lemon S3 Alex

    Joined:
    Sep 1, 2009
    Messages:
    1,378
    Likes Received:
    34
    This is only useful when you're stationary, the way the air travels over the bonnet when moving doesn't let any air out. This is not called the Venturi effect.
     
    #6 Lemon S3, Mar 19, 2013
    Last edited: Mar 19, 2013
  8. 16Klappe

    16Klappe I <3 Panda's!
    Supporter

    Joined:
    Sep 16, 2008
    Messages:
    5,796
    Likes Received:
    1,182
    No it's not?! There is no fluid pressures involved for it to be classed as a venturi, the technical term is "**** airflow."
     
  9. Lemon S3

    Lemon S3 Alex

    Joined:
    Sep 1, 2009
    Messages:
    1,378
    Likes Received:
    34
    Soz, you're right, confused myself with the proper meaning for the effect of pressure at the back of the bonnet. Still....lifting the bonnet doesn't make a difference when in motion.
     
  10. s3dave

    s3dave TFSI Hybrid
    Supporter

    Joined:
    Nov 11, 2009
    Messages:
    10,114
    Likes Received:
    736
    And guess where the ECU lives....
     
  11. jojo

    jojo Looking for Boost!
    Staff Member Moderator Team Daytona quattro Audi S3 Audi A6 Audi Avant Owner Group

    Joined:
    Sep 4, 2003
    Messages:
    28,662
    Likes Received:
    3,346
    Just remove the bonnet all together! :idea:
     
  12. bigwhitetruck

    bigwhitetruck New Member

    Joined:
    Mar 15, 2013
    Messages:
    10
    Likes Received:
    0
    The first reason for liftinG the bonnet was so u could shoe horn a bigger/taller engine in the bay without using differnt mounts

    mainly civics with 2.2 engines
     
  13. jimmcgee

    jimmcgee Active Member

    Joined:
    Dec 29, 2011
    Messages:
    233
    Likes Received:
    32
    wrong , think rs turbo , way before jap ****
     
  14. Birdy

    Birdy Member

    Joined:
    Sep 21, 2012
    Messages:
    71
    Likes Received:
    1
    Put a Subaru scoop on it lol
     
  15. Gops

    Gops Badger 5 Edition
    VCDS Map User Gold Supporter Audi S3

    Joined:
    Nov 6, 2009
    Messages:
    3,132
    Likes Received:
    612
    Or a toilet flap or poop scoop like top gear?
     
  16. bigwhitetruck

    bigwhitetruck New Member

    Joined:
    Mar 15, 2013
    Messages:
    10
    Likes Received:
    0
    Back in the day mark 1 rs ts had no bonnet vents so we used to fit them to let the heat out then ford released the mk2 Rs which came with vents in the bonnet and back in the day we wouldn't dream of ruining the lines by raising the bonnet at the rear

    i have been around a long time!
    And it was jap scrap in the states that started it

    It was a/is schoolboy mod
     
  17. superkarl

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    9,153
    Likes Received:
    2,178
    in summer i just take the seal out from the back of the bonnet just to let heat escape whilst moving slowly through traffic or whilst stationary. You can see the heat escaping. But it will only escape whilst stationary or not moving very fast.
     
  18. voorhees

    voorhees Moderator
    Staff Member Moderator Black Edition Team Brill Red

    Joined:
    Dec 18, 2005
    Messages:
    16,080
    Likes Received:
    1,899
    [​IMG]

    This seal ?
     
  19. superkarl

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    9,153
    Likes Received:
    2,178
    Thats the bugger!


    Lmao. How didnt i see that!
     
  20. s3clarke

    s3clarke Money grabbing s3!

    Joined:
    Jun 8, 2012
    Messages:
    677
    Likes Received:
    35
    this is the bugger who stuck fingers (if that's what there called on a seal) in my turbo compressor wheel! Bent 1 of my blades the f*cker!
     
  21. mk1chopper

    mk1chopper Missing the S3

    Joined:
    Oct 17, 2006
    Messages:
    1,093
    Likes Received:
    11
    It must have some effect whilst moving, hot air under the bonnet will have a higher pressure than the air flowing over the bonnet, the high presure air will want to go to the low pressure air, the gap at the back should act as a heat extractor. If you fit bonnet vents they dont force cold air into the engine they draw hot air out, some cars have vents in the wings, like the escort rs cosworth or clio 197/200 which work in the same manor. Although some cars do have a scoop like scoobys and GT4s that force air into the engine or intercooler on these cars.
     
  22. Advert Guest Advertisement



    to hide this advert.
  23. superkarl

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    9,153
    Likes Received:
    2,178
    base of your windscreen/top of bonnet is going to be area of high pressure when moving. Compared to lower pressure under the bonnet. Therefore its not going escape. Its debatable that cold air might go in though

    And hence might actually be venturi effect by bernoullis principle
     
    #21 superkarl, Mar 20, 2013
    Last edited: Mar 20, 2013
  24. A3-Lee

    A3-Lee Active Member
    VCDS Map User

    Joined:
    Dec 11, 2011
    Messages:
    938
    Likes Received:
    226
    This made me laugh so much lol
     
  25. Prawn

    Prawn My other car is a MINI!!!!

    Joined:
    Dec 8, 2006
    Messages:
    11,135
    Likes Received:
    2,766
    You couldn't be more wrong.

    Base of windscreen is a high pressure area, not low, air will be drawn IN, not out by raising the back of the bonnet.

    Don't do it. No gains.
     
  26. Prawn

    Prawn My other car is a MINI!!!!

    Joined:
    Dec 8, 2006
    Messages:
    11,135
    Likes Received:
    2,766
    thank god for superK, I tried to type that 45 mins ago but my net connection is so dire it failled repeatedly.

    Thankfully, Karl has already set the record straight.
     
  27. Jason.s

    Jason.s Active Member

    Joined:
    May 12, 2010
    Messages:
    2,879
    Likes Received:
    348
    If only you could mount the filter right up under the scuttle for that high pressure. Bit like the Gruppe M intakes for EP3`s having the scoop on the scuttle.
     
  28. kwistof

    kwistof South East Events Moderator
    Regional Rep

    Joined:
    Jun 1, 2010
    Messages:
    2,435
    Likes Received:
    534
    Just had to have a quick google on the Gruppe M kit for our 8L S3's.....

    To say their having a laugh with the price is a huge understatement!

    Buy Audi S3 8L 4WD 1999-03 Gruppe M Air Induction Kits | PPCGB
     
  29. jojo

    jojo Looking for Boost!
    Staff Member Moderator Team Daytona quattro Audi S3 Audi A6 Audi Avant Owner Group

    Joined:
    Sep 4, 2003
    Messages:
    28,662
    Likes Received:
    3,346
    Wow, 900 quid!, no wonder no one has one! lol

    For 900, you could have a Badger5 3" and a Milltek cat back exhaust with a few quid change!
     
  30. Jason.s

    Jason.s Active Member

    Joined:
    May 12, 2010
    Messages:
    2,879
    Likes Received:
    348
    Gruppe M have always been spastic high on price but its nice carbon and they are good tbh but still i wouldnt ever pay for one lol.
     
  31. s3clarke

    s3clarke Money grabbing s3!

    Joined:
    Jun 8, 2012
    Messages:
    677
    Likes Received:
    35
    Honda s2000 filter all the way!
     
  32. mk1chopper

    mk1chopper Missing the S3

    Joined:
    Oct 17, 2006
    Messages:
    1,093
    Likes Received:
    11
    In principal I was correct, higher pressure will want to go to low pressure, but I hadnt taken into account higher pressure at the base of the windscreen. One question though if air is being forced in due to the high pressue at the base of the wind, is the air being forced in cooler than the air under the bonnet and would this have any benefits? Would lifting/removing the seal be benficial in certain circumsatnces, the high pressure area at the base of the windscreen will be speed relative,so say for example your are tracking your car which has several slow speed corners during these slow speed corners would you see lower pressure at the base of the windscreen and the reverse happening (heat extraction). The gains might be tiny but im just woundering if this would aid cooling in this situation.
     
  33. superkarl

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    9,153
    Likes Received:
    2,178
    Without stupidly minute testing, you could never answer that.

    Based on the theories you could say the air going in would cool things. But who reeeaaally gives a **** for a few degrees
     
  34. Lemon S3

    Lemon S3 Alex

    Joined:
    Sep 1, 2009
    Messages:
    1,378
    Likes Received:
    34
    Hear hear! Plus people constantly tell you your bonnets open.
     
  35. Schlaag

    Schlaag Bwah

    Joined:
    Jul 10, 2007
    Messages:
    476
    Likes Received:
    32
    No, you will look like a c*nt!
     
  36. s3clarke

    s3clarke Money grabbing s3!

    Joined:
    Jun 8, 2012
    Messages:
    677
    Likes Received:
    35
    it just looks like you've had a front ender as well!
     
  37. Paradox1

    Paradox1 Active Member

    Joined:
    Aug 3, 2011
    Messages:
    1,833
    Likes Received:
    88
    It looks alright on a track car but not something I would want to do as there is no gain I guess.

    I supposed you could fit some washers on the bolts to raise it up a bit but im good with how my bonnet is now
     

Share This Page