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N52 Swap (RHD)

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    N52 Swap (RHD)

    So I happened to stumble upon cwlo 's N52 thread about a year ago just as I was deciding what to replace my gutless M20B20 with. I was instantly sold after hearing about how the entire engine was designed for lightness with a truly NA torque curve and power levels pushing close to an S54 (with headers, an N54 manifold and tune). The more I read, the more it seemed the perfect engine for an E30... It's the weight of a 4 pot with more power than an S14 and most importantly, that creamy straight-six soundtrack.

    After spending weeks searching, I managed to bag myself a running E90 330i manual donor car for the pretty great price of £1000 (around $1250). Considering an entire engine costs this much I was rather pleased with this purchase ​. Even in the boat that is the E90, the broad torque band surprised me and the top end made me realise just how out of puff my N55 daily gets. Anyway, after a few weeks of enjoying it and finishing rust repair on the E30, I started ripping the poor 330i apart to harvest its organs.
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    As far as I can tell, nobody has done a right hand drive N52 swap (I'm located in the UK) so I have the added complication of getting the headers/exhaust manifold around the column. I noticed cwlo had to spend a fair while getting round oil pan and pickup modification which I decided to avoid. After spending days researching Ackerman and bumpsteer, I decided to bite the bullet and move the rack forward to accommodate the stock rear pan of the N52. This required some subframe modification and custom steering rack brackets but the end result is that the engine remains untouched and the rack remains serviceable. The tie rod ends still point slightly backwards and the height of the rack is only 10mm lower than it's original position. For the subframe I used Garageaholic 's idea for inspiration and used a tubular cross member to join two steel plates.
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    Once the engine was positioned, the next step was to connect the driveshaft and mount the drivetrain. I used a Z4 N52 front prop and joined it to an E36 328i rear prop (same length as an auto M3 in the USA). Installed an early model E30 centre support bearing and the spline engagement was perfect - around 2 inches. After loosely connecting the propshaft to the transmission guibo and ensuring it was square, I modified the original M20 trans cross member to hold the new ZF GS6-37BZ. This consisted of re-drilling the holes for garagistic 80A mounts and welding in spacers to get the height perfect.

    For engine mounts, I used Z4 N52 mounts with garagistic 80A mounts. These placed the engine around an inch too far forward and I noted that cwlo addressed this by cutting and re-welding the Z4 mounts. Unfortunately, I don't have access to a tig welder and can't weld aluminium so instead opted to re-drill the mount locations. As I already modified the subframe it was easy enough to open up enough access for a nut on the underside.

    So at this point, the engine and trans were mounted in the car and the steering rack was in it's slightly new location. The steering column requires lengthening and I will need someone to tig this as it is made of aluminium. All steering lines fit perfectly with the existing e46 purple tag rack and the E90 steering pump so this was nice and simple. I still need to decide how to mount the E90 power steering cooler which should help with spirited driving/track work.

    Moving onto cooling, I managed to slide the E90 radiator into the E30 chassis after sanding down one of the plastic brackets. Clearance is tight but there is 5mm either side of the rad which will work. I welded L brackets to support it from the bottom and used to weld nuts to secure it up top. Once mounted, it was clear the original puller fan would not fit which was a shame but I managed to source two 10 inch fans rated at 1000cfm each. These are thin enough to be used as puller fans and were installed using custom mounts. Ideally, I'd like to retain the DME control of the cooling fans (controlled by PWM). I'm not 100% sure whether my solution will work but I found an E87 120d fan control module which takes the DME signal and outputs DC voltage. Hopefully this module can be wired to the aftermarket fans giving OEM function. Coolant hoses don't seem to be too difficult but I have yet to sort these. The most difficult appears to be the lower thermostat to radiator hose which is tight. As I am performing an AC compressor delete there is ample room for the thermostat to be relocated to provide extra space.

    After some more research, I purchased an N54 intake manifold on eBay for £50 ($60). The extra space in the engine bay alone is worth it but combined with the minimal torque loss at low rpm and the gains at high rpm it was a no-brainer. I'll be revving this thing as much as possible and combined with a raised limiter to around 7500rpm, it should make for a great NA power delivery. This also means there will be loads of space for the E90 booster and master cylinder which will be connected up to the new Kunifer brake lines that I made up today. From what I've read, this will require an N54 throttle body and a tune to make things run properly.

    The aim for this car is to be a great driver's car with a direct, mechanical feeling. With this in mind, the gearshift quality had to be perfect. After coming across chassis mounted shifters, I decided I had to have one and wasn't going to spend £3/400 on one. I ordered an M12 spherical bearing and an M12 threaded rod and fabbed my own. As I have a pre-facelift E30, my shifter housing was the sheet metal version which had a perfect cup to weld the spherical bearing into. This was then bolted onto the trans tunnel and the threaded rod was adjusted until I achieved the perfect throw length. I then welded the bottom of my original shifter onto the rod and fabricated a DSSR to connect it to the transmission. Using nylock bolts, I was able to add some drag and adjust this until the shift quality was exactly the way I wanted. End result - perfection.

    For the clutch, I connected the existing 3/16 inch line directly to the E90 slave cylinder and binned the clutch delay valve (nobody needs that junk!).

    That's pretty much as far as I have got up to now. Next few things to do are fuel system, exhaust and coolant hoses. After that most of the mechanical stuff will be done and we can move on to the dreaded Wiring!

    The early E30 fuel systems had an in-tank pump feeding a second pump mounted under the car and I was initially going to mimic this setup. Instead, I've decided to use the E90 in-tank pump as the only pump and will see if I suffer any starvation (will install a swirl pot and second pump if I do). This will be connected to an S54 fuel regulator and hoses will be PTFE braided ones. I will also need to install the fuel pump module from the E90 (EKP).

    For the exhaust, I initially toyed with the idea of building custom long tube headers that snake around the steering column before realising that this was probably beyond me at this point. Instead, I will be cutting out the primary cats from the original manifold and replacing them with straight pipes. Waiting for the 304 stainless pipe to arrive so will be doing that next week. (as a side note, does anybody know what stainless grade BMW use for their OEM manifolds?)

    Finally, we move onto wiring. Now at this point I have to say I'd have never attempted this swap if I hadn't been given hope by nando . Just knowing that it is possible to delete EWS and CAS on the MSV70 reassured me enough to dive into the swap and at worst I can always transfer the extra wiring/modules and have a start/stop button (even though I'd prefer the old-fashioned key). From the weeks I've spent studying wiring diagrams, I think the wiring shouldn't be too difficult and the basic things to integrate are the tach signal, the coolant temperature and hopefully an OBD2 port. As far as modules I'll need to pull from the E90, I'll need the EKP, CAS module, accelerator pedal, start/stop switch, key holder, (possibly body control module) and possibly some others I can't think of right now. Fingers crossed cwlo and nando will be kind enough to offer me some of their knowledge and expertise if I hit a wall at that stage and I know they want to see more N52 swapped E30's.

    Have to say a massive thank you to cwlo, nando and Garageaholic for their detailed information on their N52 and N54 swaps respectively.

    More updates to come...
    Last edited by Saturnblau; 05-10-2020, 03:32 PM.

    excited to see the build but the pics are dead for me!
    85% of the time i have no idea what I'm doing


      Nice to see your progress, although the pics are not working. If you are running the ews delete msv70, then you don't need the CAS and key holder. Wiring is really not too bad. Good luck, I'll keep an eye on the thread and progress.


        Hopefully you can see them now.. only let me add five so I'll add a few more here.

        First up is the radiator...
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        Then we have the N54 manifold...
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        And finally my new gearstick! (will have the gaitor and oem knob on don't worry)...
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        Just spent today ripping out the interior of the E90 for it's main wiring harness, fuel pump, EKP and DME. More progress updates incoming.


          Ok, stupid quesion, but does the RHD brake booster still reside on the left?
          I am definately following.


            hoveringuy indeed it does! Has a rod that goes across from the pedal under the dash and a pivot to push into the booster.


              Cool to see some progress! I think I got an email from you about the swap DME. I'll get back to you as soon as I can.

              My N52 is still sitting on a stand, sadly.
              Build thread



                nando you have to get your own N52 running before you help anyone else! Is the ix layout still causing clearance issues?


                  there's already a few N52 swaps, and at least one N54 swap that I helped with. ;)

                  Sorta - I need to get the oil pan modified. I have basically everything else. But I also need to build the engine, and I just don't have time to mess with it unfortunately.
                  Build thread



                    BTW, so far we haven't used the E90 EKP in any swaps. We have found the Z4 calibration for MSV70 works better in a swap situation (we ran into some strange issues with the E90 calibration), and the Z4 EKP would need to be used. I think it might be possible to flash the E90 EKP with the Z4 EKP calibration, but I have never tried. The main difference is the E90 uses the BN2000 CAN protocol, while the Z4 uses the older CAN11h (like the E46). Another possibility is to modify the DME to use a regular relay, but that hasn't been attempted yet.

                    You don't need much of the E90 harness. Probably just whatever is needed to power the DME, and of course the engine harness itself. I bet you can make some money back parting out the rest of the car!
                    Build thread



                      oh, I also forgot another thing - the N54 manifold doesn't match up with the ports on the N52 head perfectly. I think you have to slot the holes on the manifold to line it up better. If you can fit it, the 3-stage manifold is best for the street, but it probably hits the brake booster.

                      and you don't need the CAS at all. Unless you're trying to keep push button start and swap a bunch of other stuff from the E90 over.
                      Build thread



                        I know you’ve helped a few people but go and enjoy yours too! If this project has taught me anything it’s that progress is inversely proportional to time and money 😭

                        I do remember reading something about the e90 EKP but I’m leaving all the wiring/modules alone until I’ve got the hardware installed. Worst case, I can pick up a Z4 module!

                        One thing I’d like to ask is regarding the cooling fan module.. my OEM fan has the controller built in but I’ll be running twin 10 inch 12v DC fans as pullers. I’ve picked up a cooling fan module from an e87 N43 which I’m hoping will take the PWM signal from the DME and I can splice the powers out to each aftermarket fan. (Each fan has a third of the amperage requirement of the oem fan). Do you see any reason this wouldn’t work?

                        I’ve still got the 3 stage manifold and I’m considering chopping it up to use the runners going into a custom plenum. I’m after as much top end power as possible and I’m happy to sacrifice a little torque to hear the thing scream. Turbo torque is everywhere nowadays and I’m craving the feeling of a good old NA engine which you have to keep in the powerband. Maybe that’s a better route than the N54 mani but I’d hate to do all that if it ended up being worse.