Stock piston options?

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  • Cinnabar325is
    E30 Enthusiast
    • Mar 2011
    • 1064
    #1

    Stock piston options?

    Building a motor for a spec E30 car. Early 'i' motor with deep skirt pistons. The skirts have some excessive scuffing and wear according to the machinist and he recommended against reusing them.

    Spec E30 limits overbore to .020".

    What new, stock type piston options are out there? I can't seem to find any 8.8:1 compression, cast pistons at the stock diameter or less than .020" over.
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black
    Tags: None
    • Roland H
      R3V Elite
      • Mar 2009
      • 4480
      #2
      You can't buy OEM pistons for it?

      The first overbore pistons from BMW are like .010" over

      $125 each.

        Comment

        • SkiFree
          R3VLimited
          • Jun 2011
          • 2766
          #3
          The available OEM Mahle's are 84.50 mm, +0.50mm (+.020") over, Mahle recently did another run of these so availability shouldn't be an issue. This is usually the most common route for a spec e30 engine. The other option (if you're brave enough) are the over-seas cast maxsill pistons (some sets I've seen are useable, others not so much. It's a qc thing more than anything).

          **EDIT: not to try and sell you anything, but I've got the Mahle's on the shelf.
          Last edited by SkiFree; 03-05-2014, 04:41 PM.
          ADAMS Autosport

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            • Cinnabar325is
              E30 Enthusiast
              • Mar 2011
              • 1064
              #4
              Originally posted by Roland H
              You can't buy OEM pistons for it?

              The first overbore pistons from BMW are like .010" over

              $125 each.
              Sure, could you give me a link? I found the pistons on realoem, but there was not part number listed. And I haven't been able to find the OEM pistons elsewhere.
              '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

                Comment

                • jlevie
                  R3V OG
                  • Nov 2006
                  • 13530
                  #5
                  The only legal pistons for this engine are the OE (from BMW) or OEM (from Mahle). You can legally use the later "weight improved" .50mm over OE pistons (part 11251735758).
                  The car makes it possible, but the driver makes it happen.
                  Jim Levie, Huntsville, AL

                    Comment

                    • Cinnabar325is
                      E30 Enthusiast
                      • Mar 2011
                      • 1064
                      #6
                      Originally posted by jlevie
                      The only legal pistons for this engine are the OE (from BMW) or OEM (from Mahle). You can legally use the later "weight improved" .50mm over OE pistons (part 11251735758).
                      What do you mean "weight improved"? I'm guessing they're lighter than stock, but .020" larger?

                      While we're at it, do you guys have a line on new OEM M20 camshafts? Again for the spec E30 car. The old cam is too worn.
                      '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

                        Comment

                        • Roland H
                          R3V Elite
                          • Mar 2009
                          • 4480
                          #7
                          All of these are "weight improved." The early model ones are the four listed near the bottom.

                            Comment

                            • SkiFree
                              R3VLimited
                              • Jun 2011
                              • 2766
                              #8
                              Originally posted by Cinnabar325is
                              What do you mean "weight improved"? I'm guessing they're lighter than stock, but .020" larger?

                              While we're at it, do you guys have a line on new OEM M20 camshafts? Again for the spec E30 car. The old cam is too worn.
                              The "weight improved" pistons are just the late short skirt pistons, what I was already referring to. The iffy maxsills I referred to are technically spece30 legal as well, just look at 9.3.1.2.2 in the rulebook.

                              As for stock cams, you can also run the Febi replacements. Bear in mind that the oem and Febi cams are made within a tolerance range. I know of a few guys who actively hoard decent cams who have them checked out to see if they can take advantage of that "range".
                              ADAMS Autosport

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