Euro M20b25 Piston Compression Height Spec

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • AWDBOB
    hooptie connoisseur
    • Aug 2013
    • 4482

    #1

    Euro M20b25 Piston Compression Height Spec

    Hey all-

    Does anyone know compression height spec for euro 9.7:1 b25 pistons, or how to identify them? I'm trying to discern if a set of replacement pistons overseas are 8.8 or 9.7:1 before I order.

    US Spec 8.8:1 as far as I can tell is 34.2mm. 206.7-(75/2)-135=34.2mm.

    This measurement also doesn't take into account the dome of the piston above deck, so perhaps CH isn't helpful?

    I found measurements of 34.090 on Yenmax 3104600050 b25 pistons.

    Yenmax specs:



    Help?
    Last edited by AWDBOB; 07-29-2026, 12:54 PM.
    1989 Hooptie 325iS Build Thread
    1989 Zinnoberrot M3 Build Thread
  • digger
    R3V OG
    • Nov 2005
    • 6137

    #2
    89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

    new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

    Comment

    • digger
      R3V OG
      • Nov 2005
      • 6137

      #3
      The way to identify is the depth/size of the valve reliefs
      89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

      new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

      Comment

      Working...