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    M50/S50 - M52/S52 Engine questions

    Well, like many of you on this board, I've long contemplated an engine transplant. To this end, I'd like to know as much about the prospective engines as possible. So let's start an m/s/50/52 engine info thread. Please post links to sites which detail the differences between the engines (pistons, cranks, heads, cams, valves, blocks etc).

    Hopefully, through this thread, questions like the following could be answered: Can you take an obd1 vanos 2.5 and bore it and/or stroke it to reach 3.2 liters displacement using s52 parts, then swap cams and, basically, have an s52.

    I'm kind of looking at interesting alternatives to a plain m50 swap. The motors seem plentiful and relatively affordable, and it would be fun to buy a thrashed one and do a performance rebuild, hopefully to exceed s52 hp etc. What's the cheapest way to 300 naturally aspirated hp with these engines? For example, could this kit be incorporated into an m50 with different crank and/or rods to create an s52? http://cgi.ebay.com/ebaymotors/ws/eB...tem=2461304057

    So, with that introduction, let's flood the board with info about these engines, including links etc. Have at it and have fun.

    #2
    I don't have any links, but I can tell you quite a bit. We will go by year model.

    M50B25-Non-vanos 2.5L. Only 2.5L block that can be bored to fit M3 pistons. Max boring by BMW is 85.4mm, but you can take it to 86mm no problem.

    M50TUB25-Vanos 2.5L. Max boring is 85.5mm.

    S50B30US-Vanos 3.0L. 86.5mmX86mm. 3029CC.

    M52TUB25-Vanos 2.8L. 84mmX84mm.

    S52B32US-Vanos 3.2L. 89.5mmX86.5mm. 3178CC.

    All Vanos engines are single step Vanos. Non-vanos engine came with double valve springs. The valve stem is 7mm vs. 6mm for vanos counterparts. The valve seat on non-vanos engines is 32.4mm exahust, and 28.8mm intake. Vanos engines are 28.8mm exhaust, and 26.8mm intake. All these numbers are straight from BMW. Stuart will disagree with me that the non-vanos valve heads aren't bigger, but for some reason I don't forsee BMW being wrong. 2.5L vanos engines have single valve springs, and non-forged retainers. 2.8L, 3.0L, and 3.2L engines have M3 conical valve springs, and the nitride forged retainers. Pre-10/95 3.0L's had a weaker retainer, but all new 95-99 retainers are made with the new process.

    Now, on to building engines. There are many different options. The 3.0L crank is not forged, where as the 3.2L crank is. The 3.2L crank is roughly 10lbs lighter, and forged. With the lighter 3.2L crank, to balance right you need to run 3.2L pistons or custom JE, Wisco, Ross etc... pistons. To 'make' a 3.2L, you need a 3.2L block, but can use a 3.0L block. There is NO M50 block that will work. A 3.2L block can take up to 86.6mm of bore, atleast according to BMW. To make a TRUE 3.2L, you need to have that extra .1mm of bore. But that is beyond the point. To me, the ideal engine is a knife edged 3.0L crank, with .020" over pistons. That would get ride of the extra 10 lbs, aid in lubrication due to the knife edging, and helps with cutting through the oil. That would make a perfectly square engine. Another idea that intrigues me is the crank from the 524TD. It is forged, and its stroke is 78mm. 78mmX84.5mm would make a sick revving engine, and due to the forged internals, build the head and turn it up to say 7800 or so. Just another thought that won't ever make it past a thought.

    Thats just some information for you. Feel free to ask whatever you want.

    Wes

    Comment


      #3
      Basic engine information:

      The block castings are all similar, with the main difference being dimensions. The 325 blocks are generally the smallest...then the 328 blocks...then the M3's being the largest.

      Cranks:
      325-- Cast, 75mm stroke.
      328-- Forged, 84mm stroke.
      3.0L M3-- Forged, 85.8mm stroke
      3.2L M3-- Forged, 89.6mm stroke

      Pistons:
      325-- 84mm bore
      328-- 84mm bore, graphite coating (reduced friction)
      3.0L M3-- 86mm bore
      3.2L M3-- 86.4mm bore, graphite coating

      '91-'92 325 blocks can take 86mm pistons. '93-'95 325 blocks cannot safely go over 85mm.

      Heads:
      The heads are all very similar, with the non-VANOS head being slightly different (valve stem size, valve spring setup). The '96 and later heads seem to have larger intake ports with only slightly larger valve pockets.

      Cams:
      non-VANOS 325's had 240/240 cams.
      VANOS 325's had 228/228 cams.
      M3 (3.0 and 3.2) has 252/240 cams.
      I believe the 328 has 228/228.
      (note: You cannot put VANOS cams in a non-VANOS motor, and vice versa)

      Valvetrain:
      325's have 35mm tappets.
      M3's have 33mm tappets.
      non-VANOS 325's use double valve springs
      VANOS 325's use single-cylindrical springs.
      M3's use a conical, progressive rate, lightweight spring.

      If you plan to build a motor to turn 7000 or greater, I highly recommend using M3 tappets, trays, valve springs, retainers, etc.


      The non-VANOS engine DOES NOT have larger valve seats, only the stems. If they did have larger intake/exhaust valves, everyone would build 3.0L+ non-VANOS engines.

      This is just some information, mostly just rambling. Let me know if you need any specifics.

      Comment


        #4
        You should try Robert(rwh11385) for info on the M50/S50 swap. He usually rapes these posts with helpful information due to all of his extensive research on this project.
        ________
        lamborghini wiki
        Last edited by Wes325; 01-22-2011, 12:26 PM.
        - 318is 4 life

        Comment


          #5
          Stuart,

          I would like to show you exactly what I am talking about. When is the next time you will be in town? This weekend I should have the non-vanos head off, and I will 'mic' everything. Straight from the TIS:

          M50B25-28.8mm/32.4mm
          S50B30US-28.8mm/28.8mm

          Am I missing something? I just looked again, and yes it could be wrong. It has been before, saying that a 1987 325is has a Getrag 220 transmission. I understand that you have a shitload more experience, but for the past 3 months I have been reading and studying every possibly source about building a BMW engine, top to bottom. Also, one more thing regarding the non-vanos engine, there is no alternative for retainers without having custom ones made or going with BMP/VAC/others titanium retainers. Schrick has forged 7mm retainers, but the sales rep at Korman Auto said that they have failed at 7200rpms or so.

          Please help me if I am wrong, but what I posted is exactly what I have seen/read, actually in two different places.

          Wes

          Comment


            #6
            Wow. Lots of good information to start with. Here's a few questions I'll throw out.

            Let's assume two different budgets. One that can afford only the non-vanos m50, and one that can afford the better s50/52 motor. What's the cheapest way to displacement and hp with the non-vanos m50 (the limited budget motor) and what amount of hp certain mods would yield (ie m3/schrick cams, exhaust, intake, etc . . .)?

            Now for the other end of the spectrum - the high budget motor. what would it be? Is it as simple as taking a basically stock s52, mildly massaging the internals and head and doing an obd1 swap with the typical chip/intake/exhaust/cam upgrades?

            Comment


              #7
              Originally posted by JRowe
              Wow. Lots of good information to start with. Here's a few questions I'll throw out.

              Let's assume two different budgets. One that can afford only the non-vanos m50, and one that can afford the better s50/52 motor. What's the cheapest way to displacement and hp with the non-vanos m50 (the limited budget motor) and what amount of hp certain mods would yield (ie m3/schrick cams, exhaust, intake, etc . . .)?

              Now for the other end of the spectrum - the high budget motor. what would it be? Is it as simple as taking a basically stock s52, mildly massaging the internals and head and doing an obd1 swap with the typical chip/intake/exhaust/cam upgrades?
              The best bang for the buck is probably just buying a '95 M3 engine, complete with all it's accessories and wiring, and slapping it in an E30 325, retaining the E30's tranny/driveshaft differential. These motors are 240horse out of the box, and simple mods (Euro MAF sensor, altered fuel pressure/larger injectors) will yield nice gains on the Motorsport engines.

              For a built 2.9/3.0/3.1 non-VANOS motor, with M3 spec (or similar) camshafts, expect similar horsepower figures to an M3 engine.

              Going all the way with a 3.2L can yield about 310-320 horsepower, but that is for the track only. That would be a short-use, high-wear engine that should get a rebuild more frequently. You have to be careful modding these engines, you don't want to just get the wildest cams you can find. You have to keep torque in mind, since this is where these motors have the ability to shine compared to their Euro 6-throttle counterparts.

              Note: Andy Watt's 3.2 race motor that we built puts 268 to the wheels on a Dynojet (about 325 crank HP).


              Wes---Please give credit to the Alex and Pete McHenry for introducing the thought of a 2.7L M50 that can turn 8000+.

              Comment


                #8
                Wes---Please give credit to the Alex and Pete McHenry for introducing the thought of a 2.7L M50 that can turn 8000+.
                vanos or non stu?

                Comment


                  #9
                  Originally posted by bahnfire
                  Wes---Please give credit to the Alex and Pete McHenry for introducing the thought of a 2.7L M50 that can turn 8000+.
                  vanos or non stu?
                  Either way really. Non-VANOS would be simpler.

                  Comment


                    #10
                    hot damn cause i scored a free nonvanos m-fitty. just have to save some money up i guess..

                    Comment


                      #11
                      Originally posted by bahnfire
                      Wes---Please give credit to the Alex and Pete McHenry for introducing the thought of a 2.7L M50 that can turn 8000+.
                      vanos or non stu?
                      stu, any more info on this? also a question i was hoping would get answered is, what would be the best, most potent streetable M50 without a concern for price, with reliability being one of the key factors. i think it would be interesting to see how the highest performing M50 compares to a maxed out S50, while still carrying a life expectancy of 100k+ miles.

                      Comment


                        #12
                        Originally posted by MattM20
                        Originally posted by bahnfire
                        Wes---Please give credit to the Alex and Pete McHenry for introducing the thought of a 2.7L M50 that can turn 8000+.
                        vanos or non stu?
                        stu, any more info on this? also a question i was hoping would get answered is, what would be the best, most potent streetable M50 without a concern for price, with reliability being one of the key factors. i think it would be interesting to see how the highest performing M50 compares to a maxed out S50, while still carrying a life expectancy of 100k+ miles.

                        Again, the M50/S50 engines are extremely similar with the exception of the internals. Yes, the block castings are slightly different dimensionally, and the later heads are slightly different with more port-work from the factory...but you can meet/exceed this porting by doing headwork on an earlier head.

                        They are all 24v 6's with hydraulic valvetrain....everything is the same layout, they just use different parts (pistons, cranks, rods, cams, springs, etc.)

                        Comment


                          #13
                          So with the exception what valves/springs/cams are used, the heads are all the same dimmensionally (inc intake/exhaust ports/location and bolt patterns) for vanos cars (328s and m3s) and non vanos cars?

                          Comment


                            #14
                            I am glad i found this thread i was about to start one very similar +1 for search feature.

                            Anywho so i am looking to get a M50 non vanos put into my car. my question is what do you need to do the S50 conversion? As well i second "MattM20s" qestion

                            Comment


                              #15
                              Holy thread revival Batman, but...

                              According to this thread, with regards to cams -
                              non-VANOS 325's had 240/240 cams.
                              VANOS 325's had 228/228 cams.
                              M3 (3.0 and 3.2) has 252/240 cams.
                              I believe the 328 has 228/228.
                              (note: You cannot put VANOS cams in a non-VANOS motor, and vice versa)

                              My question then is, if doing non-VaNoS M50 stroker (with M54B30 rotating assembly) what would be the best option for upgrading my cams? Since I can't use VaNoS cams in a non-VaNoS build, is a Schrick intake cam the best/most reasonable option? I've got everything nailed down for my build, with the exception of cam choice. Thanks for your help.

                              Chris
                              Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

                              Comment

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