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lifting the back of the bonnet to let hot air out

harvey01 Mar 19, 2013

  1. harvey01

    harvey01 Registered User

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    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
     
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  3. James TQ

    James TQ Registered User

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    it catches on the wing and takes paint off
     
  4. 16Klappe

    16Klappe Man Boost! Supporter

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    Just no.
     
  5. StaceyS3

    StaceyS3 Registered User

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    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

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    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

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    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.
     
    Last edited: Mar 19, 2013
  8. 16Klappe

    16Klappe Man Boost! Supporter

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    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

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    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

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    And guess where the ECU lives....
     
  11. jojo

    jojo Looking for Boost! Staff Member Moderator

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    Just remove the bonnet all together! :idea:
     
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  13. bigwhitetruck

    bigwhitetruck Registered User

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    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
     
  14. jimmcgee

    jimmcgee Registered User

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    wrong , think rs turbo , way before jap ****
     
  15. Birdy

    Birdy Registered User

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    Put a Subaru scoop on it lol
     
  16. Gops

    Gops Badger 5 Edition VCDS Map User

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    Or a toilet flap or poop scoop like top gear?
     
  17. bigwhitetruck

    bigwhitetruck Registered User

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    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
     
  18. superkarl

    superkarl MAN OF STEEL

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    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.
     
  19. voorhees

    voorhees Moderator Staff Member Moderator

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    [​IMG]

    This seal ?
     
  20. superkarl

    superkarl MAN OF STEEL

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    Thats the ******!


    Lmao. How didnt i see that!
     
  21. s3clarke

    s3clarke Money grabbing s3!

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    this is the ****** 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!
     
  22. mk1chopper

    mk1chopper Missing the S3

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    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.
     
  23. superkarl

    superkarl MAN OF STEEL

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    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
     
    Last edited: Mar 20, 2013
  24. A3-Lee

    A3-Lee Active Member VCDS Map User

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    This made me laugh so much lol
     
  25. Prawn

    Prawn My other car is a MINI!!!!

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    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!!!!

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    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 Registered User

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    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

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    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

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    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 Registered User

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    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!

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    Honda s2000 filter all the way!
     
  32. mk1chopper

    mk1chopper Missing the S3

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    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.
     
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  34. superkarl

    superkarl MAN OF STEEL

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    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
     
  35. Lemon S3

    Lemon S3 Alex

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    Hear hear! Plus people constantly tell you your bonnets open.
     
  36. Schlaag

    Schlaag Bwah

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    No, you will look like a c*nt!
     
  37. s3clarke

    s3clarke Money grabbing s3!

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    it just looks like you've had a front ender as well!
     
  38. Paradox1

    Paradox1 Registered User

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    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
     

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