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    M20b23 adding power

    Hi guys, I'm new to the e30 world and just got myself a e30 M20b23 with manual transmission. Can someone advice what I can do increase the power please without going force induction.

    For an example in my m50 previously I stroked it to a 3.0 by using m54 internals. Is something like that possible for the M20b23.?

    Looking forward to your advice. Thanks in advance.

    #2
    You would be better off starting with the 2.5/2.7 block. The 2.3 not only had a shorter stroke, but tiny 80mm slugs.
    john@m20guru.com
    Links:
    Transaction feedback: Here, here and here. Thanks :D

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      #3
      Originally posted by Roguegenius View Post
      Hi guys, I'm new to the e30 world and just got myself a e30 M20b23 with manual transmission. Can someone advice what I can do increase the power please without going force induction.

      For an example in my m50 previously I stroked it to a 3.0 by using m54 internals. Is something like that possible for the M20b23.?

      Looking forward to your advice. Thanks in advance.
      can stroke the m20 much the same as M50 but depends what kind of engine characteristics you want more torque or do you want to rev the hell out of it?
      As stated the eta block is a better starting point as the larger bore ads plenty of cubes. People have taken the 80 mm bore out to 84 mm many times and its pretty popular in the UK but dont know if anyone has gone to 85 or 86 like is common with the 84 mm blocks from eta and M20B25

      Does yours have the 731 head casting ? i think the real early engines perhaps from e21 had the 200 casting may be wrong on that
      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


        #4
        ^^^didnt even think about the head castings. Yeah, b20 and early b23 got 200, but AFAIK, the b23's I have seen in the grey market USDM have been 731.

        Either way, the m5x stuff works with either head since they have flat/dish pistons. Just be weary of 2v vs 4v reliefs.
        john@m20guru.com
        Links:
        Transaction feedback: Here, here and here. Thanks :D

        Comment


          #5
          I put a megasquirt 2 on mine and it made a huge difference to the driveability and general fun ( 6 x ls1 coils, proper tps, wideband 02 with ego correction, idle control).

          Remember the m20b23 is 9.8:1, and the b25 is 8.5:1. So the overall power might be lower but its still a 9.8:1 2.3L which is quite snappy and fun with lots of time spent tuning. The stock l-jet and fairly conservative vacuum advance distributor really holds them back.

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            #6
            i learnt to drive on a e30 323i 1984 model in the late 90's, so much fun revved nicely
            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
              Hey guys,
              To answer u guys:
              What I want: I like the a balance or torque and also high rev. To put in context my M50b25 stroked with m54b30 internals gives me the balance I really love.

              The car is running a 731 head. By using a 2.7 block, will the 731 head compliment it and give the optimum output the engine is capable off?

              It's also on Ljet management which I read is a bit restrictive.

              Hence my conundrum ☺️

              If im reading u guys right - swap out to 2.7 block and run a megasquirt?

              Comment


                #8
                Originally posted by Roguegenius View Post
                Hey guys,
                To answer u guys:
                What I want: I like the a balance or torque and also high rev. To put in context my M50b25 stroked with m54b30 internals gives me the balance I really love.

                The car is running a 731 head. By using a 2.7 block, will the 731 head compliment it and give the optimum output the engine is capable off?

                It's also on Ljet management which I read is a bit restrictive.

                Hence my conundrum ☺️

                If im reading u guys right - swap out to 2.7 block and run a megasquirt?
                If I remember right, the putting the 731 head on a 2.7 block with no changes maintains the same compression as the M20b27(9:0.1). I was looking for a 731 head for my m20b27 for quite a while, I like the torque of the 2.7, but I ran across an S52 for a steal. Don't expect massive gains, but that engine/head with a 3.25 LSD with a lil tuning would be quite fun.

                Comment


                  #9
                  you’re not going to have anything like the 3L 24v balance from a b23 that’s naturally aspirated. It would involve changing everything except maybe the head casting to get that from an m20 and big dollars which I don’t think is your goal

                  I’d look for an eta bottom end and put the 323i 731 head on it with a cam, headers and ecu. It won’t be a m52b30 by a long shot but it will be a good step up on the b23 especially from a torque perspective and won’t break the bank if you’re able to DIY. You could get the head massaged a bit but depends on your budget
                  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


                    #10
                    Originally posted by digger View Post
                    you’re not going to have anything like the 3L 24v balance from a b23 that’s naturally aspirated. It would involve changing everything except maybe the head casting to get that from an m20 and big dollars which I don’t think is your goal

                    I’d look for an eta bottom end and put the 323i 731 head on it with a cam, headers and ecu. It won’t be a m52b30 by a long shot but it will be a good step up on the b23 especially from a torque perspective and won’t break the bank if you’re able to DIY. You could get the head massaged a bit but depends on your budget
                    yes sir, i just gave the m50b30 as an example cause it seemed pretty straight forwar. initially i thought of getting a b25/27 bottom end to swap in the m54b30 internals only to find out its not a direct fit as i will need custom pistons which slightly shorter. so i canned that idea.
                    but thanks for your advice guys.

                    now the immediate task is to source for a 325/27 bottom.

                    Comment


                      #11
                      you can put the M54B30 guts into a m20 84mm block you may need to use different slugs from an M52 or something or machine the tops and add reliefs iirc need to check the stack height. it can be done but there is a few other bits you need to get to
                      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

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