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  1. #1
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    Default Upgraded head bolts.

    Back when I used to frequent Integrale forums, upgrading to 12mm head studs and bolts was discussed quite often. Doesn't seem to get brought up on here all that often, so has anyone done it or plan to do it?
    It might be down to the fact that they were all into running large amounts of boost, 1.7bar or so, whilst we all seem more occupied with sorting out the breathing of the engine first.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
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  2. #2
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    Quote Originally Posted by Steve Webb View Post
    so has anyone done it or plan to do it?
    Planning to use them when the building starts.

    Regards,
    Marc
    In a world full of compromise...
    ...some don't.
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    Opel Astra Sports Tourer 110HP 2017
    Alfa 147 1.6 16V 120HP
    Alfa 155 Q4 2.0 16V turbo

  3. #3
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    Quote Originally Posted by Brul(tm) View Post
    Planning to use them when the building starts.

    Regards,
    Marc
    What boost are you planning for eventually? 1.35bar + or is it just for reliability\flexibility?
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  4. #4
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    Quote Originally Posted by Steve Webb View Post
    What boost are you planning for eventually? 1.35bar + or is it just for reliabilityflexibility?
    It's a fun car, so I have to wait and see what's going to happen
    I am after 400BHP, so I think I'll have to see and wait what adjustments (besides the forged bottom, worked cylinder head and different turbo) are necessary. I guess it wil probably be around 1.5 bar, but again I have to wait and see how everything works out.

    Regards,
    Marc
    In a world full of compromise...
    ...some don't.
    ___________________________
    Opel Astra Sports Tourer 110HP 2017
    Alfa 147 1.6 16V 120HP
    Alfa 155 Q4 2.0 16V turbo

  5. #5
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    above 350hp 12mm bolts are musthave... if u dont wanna have trouble.

    regards coly

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    In my opinion 12 mm head bolts would be nice - but I am not using them...From my own personal experience I would recommend using the simple sub $100.00 Cometic head gasket. I have reused mine 4 times so far and it seals perfectly. I am running between 1.35 and 1.55 bar. I am using ARP head bolts - but just the normal diameter.

    There are so many thing to spend money on with these cars, but for me the stronger head bolts would not be on my list.

    Also I have found that with the right cams you cam make a lot of power without needing more than 1.4 bar boost - And that is on a car with no inlet manifold porting at all..

    cheers, jim.

  7. #7
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    mpampis_ is offline Running smoothly
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    i think, if you porting nicely the head, manifold and more aggressive cams you can have 400 hp at 1,5 - 1,6 bar boost (it depend on the tubro you have). i have to ask something else. what about the head gasket? actually about the compression ratio. the stock cr is 8.00:1, what is the max boost with this cr for not having problems?

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