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Small port vs Large port head

Discussion in 'A3/S3 Forum (8L Chassis)' started by Lemon S3, Feb 10, 2011.

  1. Lemon S3
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    Lemon S3 Alex

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    I've tried searching for this but I never have any luck with the search option for some reason.
    Would someone be able to tell me the size difference between a small port and large port head, and how much extra the large flows.
    Also what are the pros and cons of going from a small port to large?
    #1
  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    On a standard engine its not really worth it. The small port head flows enough for the standard turbo, and gives better low down torque etc, which is why Audi fitted them.

    If your planning on fitting a larger turbo, then its worth it, as the stock head starts becoming restrictive after 300hp.
    #2
  3. beachbuggy
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    beachbuggy Active Member

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    Also the inlet manifold is small port as the S3 never came with a large port manifold, so you then have to go from a small port manifold to large port head, as this happens the air speed drops but volume increases. Which as stated isn't good for low down torque unless u have a big bhp setup.
    #3
  4. badger5
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    badger5 RIP S3dave Site Sponsor

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    wellys goes all right with its largeport

    remembering audi's design criteria was 225bhp tops

    modded cars, remapped with mods... Does this still apply?
    #4
  5. Lemon S3
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    Lemon S3 Alex

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    I will be hybridding it soon so will be aiming for the same sort of power as Welly.

    Does anyone know the actual dimensions of the large port and flow rate?
    #5
  6. Dane
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    Dane Faster than a V12 Q7

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    I'm gonna stay small port and go hybrid, like Steve, if that doesn't come up near Welly's I'll think about a big port head, but, I reckon small port should see a hybrid reach good figures.
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  7. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    >head info from some blokes build thread<

    <tuffty/>
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  8. Dane
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    Dane Faster than a V12 Q7

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  9. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    #9
  10. Welly
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    Welly VX220 SC Driver :)

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    lol, my old 145000 mile bus become the new hybrid benchmark...

    It's not just about the head in all fairness, it's also about all the other flow related mods that help out in general. The thing has a colossal cooler, big pipework to fill, and the large port head as well.

    Ideally I think people looking for the hybrid should be aiming to try and keep the boost at sensible levels personally. Tried and tested.
    #10
  11. Lemon S3
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    Lemon S3 Alex

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    Does anyone know the width n height of the inlet ports as I've found a head but the owner doesn't know much about it but said the inlet port is about 55mm x 25mm.
    #11
  12. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    What engine code is the head from?

    <tuffty/>
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  13. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [​IMG]

    <tuffty/>
    #13
  14. Welly
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    Welly VX220 SC Driver :)

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    I so want one...
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  15. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    I think I need one!!!

    <tuffty/>
    #15
  16. badger5
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    badger5 RIP S3dave Site Sponsor

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    does'nt mean **** all tho does it... forcing it to do that on american dyno's vs a higher flowing head which will flow more for less boost is for me far more sensible approach. you neglected to also mention c16 fuel and 32psi of boost... hmmmm.. yea right! :p

    BT cars need large ports in their lives - lol :)
    Last edited: Feb 10, 2011
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  17. Lemon S3
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    Lemon S3 Alex

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    Thanks for the info guys, the head was a large port then. It didn't have an engine code on it for some reason.
    If I got a bare large port head, could I transfer all the parts from my small port over to it?
    #17
  18. S3 Nattie
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    S3 Nattie Quattro ist für sissies

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    Think you got to ask yourself what you want from your engine. Runinning a large head will shift your torque curve over a bit giving lower low end torque but give you better flow at high engine speed as it wont choke as soon as a small port head. Bigger isn't alway best.

    Ye, as far as I know everything is transferable
    Last edited: Feb 11, 2011
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  19. Lemon S3
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    Lemon S3 Alex

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    Well he has another bare large port head which apparently hasn't got many miles on it and he wants £100 plus £15 p+p for it. Wondering if that's a good price, the brand new head with cams went for £165 on the bay.
    #19
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