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1987 325es - Which heads are interchangeable?

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    1987 325es - Which heads are interchangeable?

    New to BMW land, but having some fun. I've recently started working on a 1987 325es. I want to take advantage of the holiday break to peel the head off and get a valve job, but think I might be better served to just buy a rebuilt head and save the hassle of dealing with the machine shop. I know these are the low performance version heads, but are they interchangeable with a better flowing head? I'm a competent engine builder, just don't know much about these older BMW's. As near as I can tell, this is the 2.7L Super ETA - does that sound right? Can you put a 325 IS head on this thing? I also considered porting this head and putting a little hotter cam in it while getting a valve job, but that doesn't seem to be the best route based on what I've read. Short of an engine swap, what are my most reasonable options here? Priority one is to fix the dead hole, but I'd really like to perk this thing up while I've got it apart. Thanks in advance!

    #2
    87 325eS is just an ETA engine 121HP. The 325i "885" head is a direct replacement and features 2mm larger valves and ports. Also has a hotter cam and dual valve springs. It's a definite upgrade but the valve pocket is different and will lower compression when installed on the ETA bottom end. Some don't mind the trade off since the gains outweigh the compression loss. These days one can get a complete 325i engine M20B25 for $300-400. You have to determine if doing an e to i head swap is worth it for what you're trying to do. 88 325 is a Super ETA, 1 year only model. It's a hybrid of a 325i engine and 325e engine so to speak. It's the engine most people build 325i stroker engines from since it features a 2.7 bottom end with domed pistons designed for the 885 head. One just needs to swap the cam, valve springs, intake, DME to make a 325i stroker.
    "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

    85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
    88 M3 - LACHSSILBER/SCHWARZE
    89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
    91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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      #3
      Great explanation!!! You just pieced this all together for me. I sincerely appreciate it.

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        #4
        One more question - I know I'll need a chip to put the 885 head to work. Is the ETA intake compatible with the 885 head? I'm actively looking for a complete motor as mentioned above, but not finding a good source just yet. Sure appreciate the help.

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          #5
          Originally posted by JimboBMW View Post
          One more question - I know I'll need a chip to put the 885 head to work. Is the ETA intake compatible with the 885 head? I'm actively looking for a complete motor as mentioned above, but not finding a good source just yet. Sure appreciate the help.
          Sure but you'd be choking the engine. The 325i intake manifold and throttle body flow more air.
          "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

          85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
          88 M3 - LACHSSILBER/SCHWARZE
          89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
          91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

          Comment


            #6
            That makes sense. With the proper intake, would a chip take care of making the computer compensating for the bigger cam and higher airflow or do you need to have it reflashed?

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              #7
              At one point back in the day in the early 90's, there were e to i chips made by Dinan that did exactly that. However, these days it makes more sense just to convert the entire fuel system from Motronic 1.0(ETA) to Motronic 1.1/1.3(Super ETA/325i) which is much better out of the box. That's another benefit of the 88 Super ETA...it ran Motronic 1.1. To take it a step further, there's programmable engine management systems like Megasquirt for even more control.
              "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

              85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
              88 M3 - LACHSSILBER/SCHWARZE
              89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
              91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

              Comment

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