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    m20 stroker confusion....

    Hey guys, I want to build myself a stroker from my 1990 e30 325i m20 engine that I have pulled out and in the process of rebuilding. I have been reading alot about the stroker and I think I have just totally confused myself with all the different information. I know that I need a crank from a '88 528e and I read that the connecting rods need to be 133mm in length in order to fit. My question is can I use the pistons from the m20 and still get the desired results? :?

    #2
    Re: m20 stroker confusion....

    Originally posted by vance325i
    Hey guys, I want to build myself a stroker from my 1990 e30 325i m20 engine that I have pulled out and in the process of rebuilding. I have been reading alot about the stroker and I think I have just totally confused myself with all the different information. I know that I need a crank from a '88 528e and I read that the connecting rods need to be 133mm in length in order to fit. My question is can I use the pistons from the m20 and still get the desired results? :?
    No, you can't use 325i pistons, you will have the wrong compression ratio. You need either pistons from an 88 325 (super-eta), 88 528e, or custom made pistons from either JE or another manufacturer.

    Also, you can use the crank from any eta motor, not just the 88 528e. I'm also pretty sure you can use the crank from a 524td, which is much stronger than an eta crank.

    Comment


      #3
      Re: m20 stroker confusion....

      Originally posted by Eurospeed88
      I'm also pretty sure you can use the crank from a 524td, which is much stronger than an eta crank.
      I don't think there is any proof to back this statement..
      Build thread

      Bimmerlabs

      Comment


        #4
        Re: m20 stroker confusion....

        Originally posted by nando
        Originally posted by Eurospeed88
        I'm also pretty sure you can use the crank from a 524td, which is much stronger than an eta crank.
        I don't think there is any proof to back this statement..
        I was under the impression the diesel crank was forged and the eta crank is cast. forged > cast in my book. Although used cranks have had years of torque twisting through them.

        He also mentioned running a different length connectng rod to change the piston height. It would probably be easier to have custom pistons made instead of using different rods. That way you can be sure you have what you need, and also gain some extra compression if desired.
        Old and improved:

        Comment


          #5
          Re: m20 stroker confusion....

          Originally posted by nando
          Originally posted by Eurospeed88
          I'm also pretty sure you can use the crank from a 524td, which is much stronger than an eta crank.
          I don't think there is any proof to back this statement..
          The forged piece is stronger. Many high performance (and race) engines use a forged crank for a reason......its going to perform better under very stressful conditions (racing, forced induction, etc.).

          In the case of a NA stroker M20, an Eta crank is just as effective as a forged unit. Nowhere near the stress though...so there isn't as great of a need for forged everything as far as internal parts are concerned.

          Jon
          Rides...
          1991 325i - sold :(
          2004 2WD Frontier King Cab

          RIP #17 Jules Bianchi

          Comment


            #6
            Re: m20 stroker confusion....

            Originally posted by vance325i
            Hey guys, I want to build myself a stroker from my 1990 e30 325i m20 engine that I have pulled out and in the process of rebuilding. I have been reading alot about the stroker and I think I have just totally confused myself with all the different information. I know that I need a crank from a '88 528e and I read that the connecting rods need to be 133mm in length in order to fit. My question is can I use the pistons from the m20 and still get the desired results? :?
            Well what are your desired results? What do you want to bore it out to? 2.7? 3.0? If you want a 2.7, the best thing to do is to start out with a good condition super eta block. If you're going to be gung ho and go all the way to 3.0, then it doesn't matter what type of block you're using. As you'll most likely be replacing the majority of everything in there anyways. At least you'll want to.

            Comment


              #7
              Thanks for all the input. I'm just trying to get a decent running 2.7. If I get the super eta block what am I going to have to do to make the head compatible?

              Comment


                #8
                Originally posted by vance325i
                Thanks for all the input. I'm just trying to get a decent running 2.7. If I get the super eta block what am I going to have to do to make the head compatible?
                nothing.
                past:
                1989 325is (learner shitbox)
                1986 325e (turbo dorito)
                1991 318ic (5-lug ITB)
                current:
                1985 323i baur (project to resume soon...)
                2013 ninja 300 (way more fun than a car)

                Comment


                  #9
                  Re: m20 stroker confusion....

                  Originally posted by Jon325i
                  In the case of a NA stroker M20, an Eta crank is just as effective as a forged unit. Nowhere near the stress though...so there isn't as great of a need for forged everything as far as internal parts are concerned.

                  Jon
                  this is what I meant. I realize that the TD crank is forged, it's just not neccesary for an NA motor.
                  Build thread

                  Bimmerlabs

                  Comment


                    #10
                    i just realized something, but can;t remember sometihng else (heh)

                    u can use an 88 eta crank... 88 eta pistons, and eta block (right?)... what about 88 eta rods? if this is case.. can;t u simply... buy an 88 eta engine, and swap heads.. (cheap easy, not dependable i know, but can you) OR do you have to use the "i" rods...

                    i really REALLY want to do a stroker, but b/c of work/school.. no time,, it sucks.. so easiest fastest way is best for me lol
                    </img>
                    Schnitzel Not Rice....

                    Comment


                      #11
                      Originally posted by Switch
                      i just realized something, but can;t remember sometihng else (heh)

                      u can use an 88 eta crank... 88 eta pistons, and eta block (right?)... what about 88 eta rods? if this is case.. can;t u simply... buy an 88 eta engine, and swap heads.. (cheap easy, not dependable i know, but can you) OR do you have to use the "i" rods...

                      i really REALLY want to do a stroker, but b/c of work/school.. no time,, it sucks.. so easiest fastest way is best for me lol
                      Yes, if you have a Super Eta engine, you can swap the entire I Top end, and have yourself a stroker.
                      - Sean Hayes

                      Comment


                        #12
                        Originally posted by Sean
                        Yes, if you have a Super Eta engine, you can swap the entire I Top end, and have yourself a stroker.
                        More commonly called a 2.7i

                        It ends up being like 8.1:1 cr. Weaksauce.

                        Hers 13 X3 375hp/450tq - His 14 M5 780hp/730tq

                        Comment


                          #13
                          Originally posted by Jordan
                          It ends up being like 8.1:1 cr. Weaksauce.
                          uhm... given that the super-eta and i heads are the same, why would the CR change? :?
                          past:
                          1989 325is (learner shitbox)
                          1986 325e (turbo dorito)
                          1991 318ic (5-lug ITB)
                          current:
                          1985 323i baur (project to resume soon...)
                          2013 ninja 300 (way more fun than a car)

                          Comment


                            #14
                            If you already have a super ETA all you need is the "i" cam, springs, intake, TB, and ECU/harness and you'll bascially have a stroker "i"...The super ETA already has the "i" head but with the ETA cam and single-coil valve springs, smaller induction setup, etc...

                            Comment


                              #15
                              Originally posted by Jordan
                              Originally posted by Sean
                              Yes, if you have a Super Eta engine, you can swap the entire I Top end, and have yourself a stroker.
                              More commonly called a 2.7i

                              It ends up being like 8.1:1 cr. Weaksauce.
                              True... But still a stroker. :)


                              Originally posted by dk
                              Originally posted by Jordan
                              It ends up being like 8.1:1 cr. Weaksauce.
                              uhm... given that the super-eta and i heads are the same, why would the CR change? :?
                              Pistons are different.
                              - Sean Hayes

                              Comment

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