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M20 Piston identification 85mm Bore

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    M20 Piston identification 85mm Bore

    Hi, I disassembled a M20 engine and found these pistons with rods, Can someone help me identify these. I have one piston crown that is cracked and need a replacement Thanks Sent from my iPhone using Tapatalk

    #2
    kinda look like these CP, just guessing though

    http://www.tmwerkes.ca/the-convertib...roker-project/
    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

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      #3
      Originally posted by digger View Post
      kinda look like these CP, just guessing though http://www.tmwerkes.ca/the-convertib...roker-project/
      Thanks, I need to look for 1 piston Sent from my iPhone using Tapatalk

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        #4
        contact CP with the code printed on them and see if its one of theirs
        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

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          #5
          Ross ?

          Comment


            #6
            Could be these

            https://bimmerheads.com/products/m20-stroker-kit
            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


              #7
              Ok Thanks. Opened engine and found piston crown broken. Any idea Sent from my iPhone using Tapatalk

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                #8
                Is that like sand blasted texture? Probably knock with a bunch of pre-ignition

                the answer is a bad tuneup and a knock prone piston design
                Last edited by digger; 01-07-2020, 10:18 PM.
                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


                  #9
                  Originally posted by digger View Post
                  Is that like sand blasted texture? Probably knock with a bunch of pre-ignition the answer is a bad tuneup and a knock prone piston design
                  Hi, What do you mean by a knock probe piston design Thanks Sent from my iPhone using Tapatalk

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                    #10
                    There's hardly any angular squish on those pistons - and they have a flat center, not a spherical dish. The m20 is a "knock-resistant" design so they could run leaner than most engines. The angled edge of the OEM piston swirls the combustion gasses towards the spark plug. When the squish band isn't used properly, the combustion can pre-ignite and knock.
                    john@m20guru.com
                    Links:
                    Transaction feedback: Here, here and here. Thanks :D

                    Comment


                      #11
                      The picture above looks quite a bit different in terms of colouring to the first post. Are they the same engine? Almost looks oily
                      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


                        #12
                        Originally posted by digger View Post
                        The picture above looks quite a bit different in terms of colouring to the first post. Are they the same engine? Almost looks oily
                        First pics is the piston cleaned up. Sent from my iPhone using Tapatalk

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                          #13
                          looks like pretty bad piston design. Look at that paper thin edge by the intake valve.....probably gets hot like crazy. Is it me or that burned up piston picture has that enfeebled totally burned off/gone.

                          I wouldn't waste any money on getting another one of those....

                          Comment


                            #14
                            The pocket edge is already machined back it’s not burnt away
                            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


                              #15
                              Yeah, but look at the original crown, by the intake valve pocket- I see signs of detonation right over the ring land.

                              OP, I'd ditch all six, based on the 2 crowns you show, and get something that's better suited...

                              sorry,

                              t
                              has broken pistons due to detonation, too.
                              now, sometimes I just mess with people. It's more entertaining that way. george graves

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