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Thread: Is this piston milled correctly?

  1. #1
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    Is this piston milled correctly?

    Does the spots milled out for the valves look correct?

    “The bitterness of poor quality remains long after the sweetness of low price is forgotten” – Benjamin Franklin

  2. #2
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    I dont know if its right but is sure is damn perty.

  3. #3
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    +1... what pistons did you buy

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    Not 100% for your engine but it looks about right to me.

  5. #5
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    Looks like a CP piston . My valve relieves look almost exacly the same.

    you can ask for specs from Tony and use a dial indicator to compare.

    here are mine

    http://www.thesocket.net/build/07302005/100_0474.jpg
    http://www.thesocket.net/build/09162005/DSCN0475.JPG
    http://www.thesocket.net/build/09162005/DSCN0476.JPG
    http://www.thesocket.net/build/09162005/DSCN0477.JPG
    Last edited by bmwperson; 01-04-2007 at 01:17 PM.

  6. #6
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    I've never seen a valve relief cut like that before, doesn't look right but if it is make sure those egdes are real smooth.
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  7. #7
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    I think the light thats just light, the jagged edge starts where the shadow ends on the upper relief

  8. #8
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    Should pistons be able to fit in connected to the rod either way? If so, there are 2 different cuts for the valves. One side is cut into the side of the piston and one side is inside the outside edge.
    “The bitterness of poor quality remains long after the sweetness of low price is forgotten” – Benjamin Franklin

  9. #9
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    intake valves are larger hence the difference in the size of the pockets. Can you confirm there are no jagged edges on the piston? or take more pics

  10. #10
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    Quote Originally Posted by Jean-Claude View Post
    Should pistons be able to fit in connected to the rod either way? If so, there are 2 different cuts for the valves. One side is cut into the side of the piston and one side is inside the outside edge.
    I'd not noticed the near side cutouts are totally different to the far side ones in your picture

    Im not sure what engine you have but the picture below is from a US M3 turbo CP piston..... *8.5:1 CP ratio*

    I would certainly take them to your local friendly engine machine shop and have them check the reliefs against the correct specification that they should be...
    Attached Images Attached Images

  11. #11
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    There is nothing abnormal about the valve reliefs being asymmetrical, in itself.
    Pistons are supposed to go one way, and probably have an arrow of some sort which may point to the front.

  12. #12
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    Are they supposed to grove like that on the edges of the piston wall? I'll be ordering CP pistons and pauter rods next month.

  13. #13
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    BTW are those from VAC? And is your set up for the S52 8:5:1?

  14. #14
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    They are CP pistons from VAC.
    “The bitterness of poor quality remains long after the sweetness of low price is forgotten” – Benjamin Franklin

  15. #15
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    Quote Originally Posted by Jean-Claude View Post
    They are CP pistons from VAC.
    Humm wounder if mines would grove like that? Get them checked out and let me know.

  16. #16
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    The larger cuts are still smooth despite cutting into the side. Here are some better images per the request.

    You can see why someone who wouldn't know better might wonder.



    “The bitterness of poor quality remains long after the sweetness of low price is forgotten” – Benjamin Franklin

  17. #17
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    With those new pictures I would say they are fine.
    Especially as they are from VAC. One way fitment.
    no problem FTW

  18. #18
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    The side with the bigger cuts goes on the intake side of the motor.
    -Kyle 1995 Custom Turbo M3 SOLD!

  19. #19
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    Quote Originally Posted by bmwperson View Post
    Looks like a CP piston . My valve relieves look almost exacly the same.

    you can ask for specs from Tony and use a dial indicator to compare.

    here are mine

    http://www.thesocket.net/build/07302005/100_0474.jpg
    http://www.thesocket.net/build/09162005/DSCN0475.JPG
    http://www.thesocket.net/build/09162005/DSCN0476.JPG
    http://www.thesocket.net/build/09162005/DSCN0477.JPG
    bmwperson, what type of coatings are those on your pistons? It looks like ceramic on the top and I don't know what is on the bottom???????

    -WTB: OEM Class 2 LTW GT wing with risers- Mazak

  20. #20
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    Hmmm. These all look similar:






    Rob - 2000 BMW Z3 M Roadster | 1986 Porsche 944 5.3L LM4

  21. #21
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    Quote Originally Posted by 3literheater View Post
    bmwperson, what type of coatings are those on your pistons? It looks like ceramic on the top and I don't know what is on the bottom???????
    With the use of our LO-KO XR2 Coating Systems for Pistons we have found extensive gains in performance and prolonged life. It is a combination coating system that helps reduce the stresses that a piston must endure during its working cycle. We achieve this by applying a low-friction, high heat transfer coating to the skirt and a thermal barrier coating to the dome.

    http://www.lo-ko.com/


  22. #22
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    Quote Originally Posted by bmwperson View Post
    With the use of our LO-KO XR2 Coating Systems for Pistons we have found extensive gains in performance and prolonged life. It is a combination coating system that helps reduce the stresses that a piston must endure during its working cycle. We achieve this by applying a low-friction, high heat transfer coating to the skirt and a thermal barrier coating to the dome.

    http://www.lo-ko.com/

    How much was the coating per piston?

    Rob - 2000 BMW Z3 M Roadster | 1986 Porsche 944 5.3L LM4

  23. #23
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    wpctreatment.com

    This reduces friction more than any coating. Numerous other benefits and applications.

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