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lots of motor questions for all you experts

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    lots of motor questions for all you experts

    Okay, I have been all over on what to do with my car. Someday as in years down the road it will get an s50, but for now it needs work and I need info on what will work and what doesnt.

    My goal is to make a 2.7 liter high output eta with a low budget. The objective is to use eta internals with eta head incorporating dual valve springs, all new guides, seals, 3 angle valve grind, and a slight deck to increase compression. I need input on what to do with the ports. I want to keep them smaller with the longer runners to make more torque but with luck I will extend the redline to 6k and will need to get more air into the motor at that time. Should the ports be opened to 'i' specs? I will also use the i throttle body and match it to the e intake.

    The next question involves the flywheel. I know my car has a dual mass which weights a lot. What options do I have there? Did the pre 86 etas have a slightly lighter flywheel, and would it be noticable? The 325i is out of the question due to the speed sesnor correct? One more ?, I heard the 323i flywheel was around 8 pounds.. compatibility?

    The motor will be finished off with a j/c chip to start unless I can use something else to bump the revlimiter up. i dont need to rev to 6500 since I hear the cast eta crank is better spun to 6k instead. The final piece would be a 3.35~3.46 differential. I want to go this route, because as it is now my car has enough power to run with i cars to a certain point. I want the low end power, So please dont tell me to get an i motor unless you know where i can get a low milage complete motor for around 450~500 bucks. I know some of you out there know a lot about these motors, I have some knowledge but not enough to start this on my own.
    Old and improved:

    #2
    Talk to Modified E30 he just built a M20 2.7i stroker. RS4Pro is in the process of building an M20 2.7i using 525e euro pistons which are compatiable with 323i heads.
    https://www.facebook.com/BentOverRacing

    Comment


      #3
      I was building one, but have quit due to lack of pistons.
      If you want to retain the stock eta block, crank, rods, pistons. the best route is the Big port 323i head on the eta block. I highly doubt you could get an eta head ported out to I specs if so You'd have to have the head x-rayed to see if there is enough material.
      The 323i flywheel lacks the sensor pick up also so the only option is a lightened single mass eta or aftermarket. I'd personaly convert the wiring, ecu, and sensors to the newer 325i Motronic 1.3. But that just is becuase it is a system that is easy to work on in my opinion. Then you can run any flywheel and any other mods.
      There are so many different ways to build these engines so it's all depends on what your after.
      85 325e 2.7 ITB'd stroker

      Comment


        #4
        Okay, that is helpful. My original intention was to try and use a 323 head. With my luck I would probably put money into something and come out with nothing. You mentioned switching to motronic 1.3.. So I can potentially (not that I or anyone would) replace my entire wiring harness and computer with the newer motronic? That means if I were to use the 323 head, I would have the newer motronic management system and then be able to use a lighter factory flywheel? That is more logical than what I originally wanted to do given the 323 hybrid yields about 160hp or so. Now, where do I find a 323 head........
        Old and improved:

        Comment


          #5
          Originally posted by EtaSport
          Now, where do I find a 323 head........
          Sitting in my dreaded basement.
          https://www.facebook.com/BentOverRacing

          Comment


            #6
            So let me get this right.

            If you swap the entire harness, ECU and sensors from an eta over to late-model 325i Motronic 1.3 items, you can use a 325i flywheel?

            What sensors do you mean?

            Comment


              #7
              Make sure to try to find a big port one(non 200 head casting)(
              to convert to 1.3 you'll need a good bit of items. TJ right now has the items you need for sale.
              here is a list
              ECu
              Engine harness
              fuel injector harness
              6 injectors
              Purge valve
              Crank sensor and crank wheel
              spark plug wire set with pulse sensor
              the two coolant sensors on the Thermostat housing(depending on the year of your car)
              TPS
              ICV
              AFM
              85 325e 2.7 ITB'd stroker

              Comment


                #8
                Originally posted by rs4pro3
                Make sure to try to find a big port one(non 200 head casting)(
                to convert to 1.3 you'll need a good bit of items. TJ right now has the items you need for sale.
                here is a list
                ECu
                Engine harness
                fuel injector harness
                6 injectors
                Purge valve
                Crank sensor and crank wheel
                spark plug wire set with pulse sensor
                the two coolant sensors on the Thermostat housing(depending on the year of your car)
                TPS
                ICV
                AFM
                EXCELLENT.

                I have a harness already, and I can get the rest of that easy enough later. I have already snagged a set of dual i valve springs.

                Comment


                  #9
                  Yea :roll: I know it's a 200 casting and I'd like to get rid of it. But a 50 lb boat anchor.
                  https://www.facebook.com/BentOverRacing

                  Comment


                    #10
                    Yes Josh, you can use any m20 flywheel, and any m20 tranny. Plus you'll have the adaptive capability of the 1.3 motronic. I'd probaly talk to Mark D. about getting a chip build as the ecu will still think you'll have 2.5 litters of displacement but most guys havn't had to much trouble running 2.7 with the 325i ecu.
                    The 1.3 motronic gets rid of those two sensors on the Tranny bellhousing and moves them to the front of the engine/spark plug wire. Plus you'll have a wider range of fuel injector choices from 19lb mustang units to E36 injectors.
                    85 325e 2.7 ITB'd stroker

                    Comment


                      #11
                      Ya Greg, I've got the 200 casting also. I plan on tossing an I cam in it and dual valve springs and just bolting it right onto my 100k milage eta block in the garage and have a slightly more power full then stock engine.
                      85 325e 2.7 ITB'd stroker

                      Comment


                        #12
                        Originally posted by rs4pro3
                        Ya Greg, I've got the 200 casting also. I plan on tossing an I cam in it and dual valve springs and just bolting it right onto my 100k milage eta block in the garage and have a slightly more power full then stock engine.
                        Then do a fake Schrick sine you are doing valves.
                        https://www.facebook.com/BentOverRacing

                        Comment


                          #13
                          Ya I probally will as you can get a race-tep reground for under $200. I won't be doing this untill after I swap in the m30 engine(which I should be picking up Wednesday if everything goes as planned).
                          85 325e 2.7 ITB'd stroker

                          Comment


                            #14
                            Okay, so if I got a 323i head, which computer set-up is the best? Didnt the e30 323 have a motronic system? I know the old e21s had L-jet and it didnt make as much power. If I got that head could I still use the eta motronic and get away with a higher rpm chip? Or is it best to swtich to the 1.3? I would rather switch to take advantage of using a lighter flywheel, but I can imagine it may get a bit pricey. I would save money by getting the cylinder head as opposed to doing all that work to an eta head though.
                            Old and improved:

                            Comment


                              #15
                              So wait, with dual valve springs, and the 173 ECU/Harness (and other goodies) the M20B27 will take the 6800 Rev's without any issue?


                              I have a set of dual valve springs from my M20B25, as well as every other part.....



                              Hmmmm, would it be worth my time to do this while I build the 2.8? Hell I gotta adjust my valves anyway...


                              /me ponders

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