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E34 M20 to S50 swap

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    E34 M20 to S50 swap

    Hey guys, I may not post much b/c Im not an E30 owner, but I do refer to the forum for technical info and expertise, especially for the M20 motor. I own an 89 525iM and have been considering several options to gain more power. Thought about doing extensive intake, head, exhaust work on the motor w/o stroking it; also considered turbocharging; and finally, fitting an S50 motor, which is what I have my heart set on heavily.

    If S50 it would definitely be OBDI. Sourcing a motor and transmission will cost money, but Im setting a budget for $7k, hoping this will cover the power expense and misc. parts along the way. I plan on doing the installation, to save money, but mostly for the challenge.

    Anyhow, just wondering what comments, advice or info you gents have. If you suggest FI over the S50 swap, or have proven power recipes for the M20, etc.

    Thanks for reading

    #2
    I think an E34 with an S50 would be great. I'd say that would be a comfortable, fun, and dependable daily driver with some extra power over other 6 cylinder E34s. And I believe with $7k you'll be able to do it comfortably and replace some wear items if need be in other areas of the car maybe?

    Basically since 525i's after 1991 came with M50's you'd just need a lot of what is in the engine bay of one. Maybe if you found a parts car 525i with an M50 you could save yourself some searching for parts? And having the two cars side by side you could see any differences in wiring.
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      #3
      curious to know if the S50 harness and M50 harness are compatable. the realoem site shows different part #'s.

      also, currently have an open 3.71 differential. would this still be a good ratio for the S50 motor/tranny package?

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        #4
        I'm unsure on the harnesses just because I don't want to give you the wrong info, wait for someone to chime in in regards to that.

        With E30S50s with the S50 ZF tranny people use a 3.25LSD because of the gearing in the tranny. I'd suggest that. Your car will still have some pickup and go, but you won't be at really high RPMs on the freeway. A 3.71 open would be too short I'd think, plus it's not LSD, and LSD rocks.
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          #5
          Hey fellow e34 M20!

          Hi everyone,

          I've been thinking the same thing. I was originally thinking FI, but decided against it due to extra strain on a tired old M20. What our cars need is a fresher engine, and the S50/S52 can bring that. I've been looking around and there are several low mileage ones out there.

          I just started researching this too, so I don't know much yet, but I found a wiring harness adapter by Treehouse racing for the E30 swaps. Maybe this is what we need too? Pretty sure we want OBD1. Maybe someone knows?

          As for trannys, I heard that the S50/52 will bolt up to the Getrag 260, but that it may not be ideal due to geometry? Maybe this is only an E30 issue?

          Also, Schneller Motoren Technik does the conversion, and I think they charge around $7k. It's on their website.

          Mark

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            #6
            I wouldnt take a chance on using my existing Getrag with the S50, it might tear it apart! I read that the transmission used with the M50 will also work with the S50, and that offers an affordable alternative. No matter what transmission is used with the S50, one big concern is the prop shaft fitment, will the original fit with the new engine/tranny package, as I dont know the lengths and where it exactly it will position itself once installed.

            My biggest concern is sourcing a motor that has not been abused. As a given, I would overhaul some major items before installation and starting, ie head gasket, piston rings, inspect and change bearings (if needed), oil pump and the nuts (important issue), clutch, water pump.

            OBDI is a given, and one option is to purchase OBDII and convert it to I, but at a considerable expense, so it's best to buy it OBDI and be done with it.

            Still researching deeper into the details. Lots of interesting details

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              #7
              You should be able to use the driveshaft from a 1991-1992 manual non Vanos M50 525i. The 525i came with the same transmission as the 95 M3, the ZF310. Because it uses the same block, I see no problem with using this driveshaft. Finding this driveshaft might be a little difficult.

              If I were you, I'd pick up a low mileage S50 in good working condition. They are really durable engines and shouldn't require a new headgasket, rings, etc. if things are already in good condition. The only thing you might want to change are the valve retainers, but even then that is a condition usually brought on by someone overrevving or spinning out. A new waterpump, thermostat, thermostat housing, and safety wired oil pump nut should all be put in.

              The M50 manual transmission, the Getrag 250, is a lesser transmission than the Getrag 260 from earlier vehicles. There's no benefit to using it except for ease of installation because the transmission won't be tilted at an angle. The clutch is the same diameter between the 250 and 260.

              Originally posted by whysimon
              WTF is hello Kitty (I'm 28 with no kids and I don't have cable)

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                #8
                Wasnt aware that ZF made manual gearboxes. Thanks for the info on the driveshaft. This eliminates much of any problems in the planning of this project.

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                  #9
                  I believe i have a 525 automatic harness on my s50 right now....either way it is definetely from an automatic m50 car. Also an E34 would be sweet especially with aggressive gearing .For example a 3.46 with a ZF would definetely surprise people off the line and once that 5er is moving it will be gone .Your lucky you wont have problems finding wide enough rims on the cheap.
                  253rwhp

                  My Vids(OLD)
                  http://www.youtube.com/user/aeryk7#p/a/u/0/hS4ZAzSdUdY
                  http://www.youtube.com/user/aeryk7#p/u/2/C-0hnV2k_xU

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                    #10
                    Ok, Im back from vacation and resuming my research. Im coming across 413 and 506 DME and EWS delete crap. If I end up having to use a EWS delete, how involved is this? What should I be looking out for here?

                    To reply on 'aeryk's' comment on wide rims, have BBS E38 style 5s currently with 225 tires all around. If I change to 245 in the rears, do you think that is wide enough rubber to handle the extra torque? Thanks for advice on 3.46 ratio input. If I want/need to change rear end ratio, it looks like just a matter of swapping the guts, the shell doesnt need to be changed. Will see what happens along the way.

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                      #11
                      Compiling the lists...

                      My part list so far...

                      OBDI S50 engine, harness, ecu and all attachments, flywheel
                      ZF S5D transmission, clutch assembly and clutch slave
                      M50 E34 mounting brackets
                      M50 E34 transmission mount support bracket
                      M50 E34 driveshaft (manual) with guibo and CSB
                      M50 E34 oil pan/sump
                      3.46 LSD differential (or similar)
                      Custom exhaust manifold and downpipes (to existing cat and BB triflow), O2 sensor(s), (might upgrade to a high flow cat)
                      E36 M3 radiator (or equivolent)
                      Engine driven fan and fan clutch
                      coolant hoses
                      fuel hoses and FPR
                      misc. vacuum hoses
                      throttle cable (still need to determine part #)
                      misc. wiring


                      Engine Upgrades (if money left over)
                      - underdrive pulleys
                      - EAT, JC or Dinan performance chip
                      - UUC ltwt flywheel and E34 M5 clutch assembly

                      My car has no AC, it was original and I tore it out since it wasn't working, and Im not interested in AC, so it's not added to the list. Most likely, whatever engine I buy will come with the compressor, and I would sell this.
                      Fitted an E36 shift lever for short-shift, will leave this unchanged. Will have to relocate battery to trunk

                      If Im missing something, please chime in...

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                        #12
                        If you are looking to save some money on the tranny the getrag 260 is more stout than the zf tranny, no money shift in the getrag, common in the zf (didn't matter if it was the regular or ///m tranny, fyi). A 506 dme (m3 ecu) will be hard to find at a good price, the 413 will work just as well and are common. Radiator can be a normal e36 one. If your e34 has Trac Cont. no need for the lsd. Call www.treehouseracing.com for questions, one of the guys there has a euro s50 in his e34.

                        Herb
                        bmpr stkr: real racers go left and right... so tru

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                          #13
                          Have you considered a M62 (or S62 8-)) V8?

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                            #14
                            Originally posted by Ferret
                            Have you considered a M62 (or S62 8-)) V8?
                            that's getting way out of my league, and I heard this is an even more difficult swap and mucho expensive. it's awesome, but not for me. Thanks for the suggestion.

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                              #15
                              I have a 413 DME if you need one.
                              253rwhp

                              My Vids(OLD)
                              http://www.youtube.com/user/aeryk7#p/a/u/0/hS4ZAzSdUdY
                              http://www.youtube.com/user/aeryk7#p/u/2/C-0hnV2k_xU

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