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    M20 engine specifications

    If anyone can provide me with these figures, I'd be grateful:

    Piston heights for the factory e, supereta and 325i pistons.

    combustion chamber volume for the 325i head.

    wrist pin location on those pistons.

    #2
    885 head is ~43cc or so.


    E30 ABS Pump Refurbishment Service
    https://mtechniqueauto.com/

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      #3
      Well.. this is odd then. If the 325i head is 43cc, then a flat-top piston should give a 9.66:1 static compression ratio. But isn't the static compression of the M20B25 is listed at 8.8:1? And don't the pistons have a bit of a rise into the CC?

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        #4
        Hm, I actually did a calculation wrong (forgot to add CC volume to cylinder volume before dividing), and with a flat top at deck height, the static CR should be 10.2:1..? Odd...

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          #5
          Hm, after some googling, seems the CC volume stock on the m20b25 is actually 47cc, which makes a flat top at deck height yield a 9.8:1, which still seems off.

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            #6
            Ah, forgot the head gasket. 9.2:1 with a flat top. Sounds more reasonable, especially since the stock pistons apparently have a dish...

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              #7
              Having a nice thread all by yourself?


              E30 ABS Pump Refurbishment Service
              https://mtechniqueauto.com/

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                #8
                Well, since nobody seems to know anything about the specs of the engine, looks like I have to.

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                  #9
                  You seem to be doing just fine by yourself...


                  E30 ABS Pump Refurbishment Service
                  https://mtechniqueauto.com/

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