No announcement yet.

N52 Swap Discussion

  • Filter
  • Time
  • Show
Clear All
new posts

    No! Please speak your part, and no need to hold back. This isn’t my build thread, it’s an n52 swap discussion.

    When I say rotation I mean rotation of the engine arm *around* the interlocked boss, with the drivetrain static. I’ll post a photo when I get home.

    Please, any information you have as you progress is going to be useful.


      Ok. Like I said. We need all the help we can get.

      This is the starboard (right/bottom/low) side of my block. It might be different on different motor arms, but on these (which I think are e90) the only socketed face is the one circled in red. If a vertical load is applied to the motor mount (green vector) the arm is going to rotate around the single socketed bolt and the two nearest the motor mount will be taking all of the shear anyway.

      I’m sure there’s loads on these in every direction, but I’d expect the greatest load to be in this direction when you hit a bump and the chassis has to move the engine up... but it’s also the same direction that the two motor mounts act to resist the torque of the engine.

      I’m not saying the socketed face doesn’t have a shear capacity, but if it was taken into account during design there 1. Aren’t enough of them on the engine arm and 2. The one that’s there is in the worst possible place.

      If the bolts through the engine arms to the block weren’t torque-to-yield I wouldn’t consider this a slip critical connection. There’s a significant amount of tension on the bolts... in fact when you pull on the bolt straight away from the block, you don’t actually increase the tension on the bolt. That seems counterintuitive, but until you exceed the bolt tension you’re actually just *reducing* the compression against the block.

      In a perfect world I wouldn’t use a washer for this connection... but I don’t think it will reduce the capacity. The friction coefficient between the faying surfaces is all that’s important, not surface area (if I’m remembering correctly)
      Attached Files


        I hear you, and I don't think you're wrong.

        But you're talking about only one mount. There's another mount on the other side with roughly the same green vector. Except, the bosses on each side of the block are on two different axis. It can't pivot unless one mount completely fails.

        Think of the aluminum boss/counterbore feature as a big fat stubby dowel pin.

        Like I said earlier, if you look at other N52 mounts for other BMW models, they have the bosses in different locations. Not sure why, but maybe just so the mounts are not interchangeable?

        Let me get some picture of my mounts so you can see the differences.


          The easiest way I can think of to keep the plate a flat piece and provide an aluminum socket for the boss would be to enlarge the hole straight through the plate, turn a socket piece with a lip less than the plate thickness, and then use a washer on top.

          The plate wouldn’t get more complicated, the socket would be simple to turn, and the washer could be steel.

          We’d have to also consider the thread engagement of the bolt though... we don’t want this piece to reduce the depth that the bolt has to grab the block.

          Here’s a great example of why I draw in cad...
          Attached Files


            Okay, here's some pictures of my Z4 mounts. They came from a 2007 E85 3.0si. With 33k miles....

            My 'thoughts' so far are that I need to move the motor back approximately 1 inch based on what I've read. So I thought I'd try to move the mounting points for the rubber engine mounts. On the passenger side (starboard), it looks fairly straight forward as long as there is sufficient thickness of material where the hole ends up. If not, I can weld a plate to strengthen it up. The driver's side is going to be a bit more tricky. Basically, I plan to bore a hole through the mount and create a large spot face on the underside of the mount. I will then turn an aluminum flange bushing that will lightly press into the bore from the bottom, and then be welded all the way around. In theory. Possibly.

            I've been looking at these mounts for a few weeks now. I can't get into the machine shop until the covid thing settles down. I'm waiting for a front subframe to arrive so I can hopefully do a mock-up on the engine stand.

            I am not actually planning to do the swap until next spring. I'm still collecting bits and pieces and my M20 is running good right now. Things could change though.

            Click image for larger version

Name:	20200625_180134 (2).jpg
Views:	372
Size:	82.9 KB
ID:	9934821 Click image for larger version

Name:	20200625_180203 (2).jpg
Views:	368
Size:	95.8 KB
ID:	9934822 Click image for larger version

Name:	20200625_180209 (2).jpg
Views:	365
Size:	86.6 KB
ID:	9934823 Click image for larger version

Name:	20200625_180216 (2).jpg
Views:	363
Size:	94.4 KB
ID:	9934824 Click image for larger version

Name:	20200625_180235 (2).jpg
Views:	364
Size:	96.8 KB
ID:	9934825


              Click image for larger version  Name:	20200625_180247 (2).jpg Views:	0 Size:	92.6 KB ID:	9934827 Click image for larger version  Name:	20200625_180305 (2).jpg Views:	0 Size:	87.4 KB ID:	9934828

              Your 'napkin sketch' above is pretty much what I was trying to suggest earlier. If you use the steel plates, try to incorporate the feature if you can. It might just be as simple as what you've drawn. But like you said, make sure you still have full thread engagement.


                Oh interesting that one of those has three bolts... and the socketed mount is directly in line with the motor mount. I would have 100% thought the socket was functional seeing only that arm.

                What was your reference for how far back you wanted the engine? The only meaningful location I could come up with was the shift carrier, and it put me a little further back than that (I think... but different arms, so the engine might be in the same place).

                I would have been waaaaaay too high on e30 motor mounts on top of the subframe, even if I’d re-drilled and reinforced it further back. Like 2” too high. Scooting back on the drivers side gets you very, very close to the steering linkage very quickly, and starts to interfere with the ball joint nuts at the same time.
                Attached Files


                  My reference for where the engine will sit comes mostly from when cwlo said this:

                  "So, I sliced the engine mount brackets, and then shifted it 1" and then re-welded. I opted to move the engine back 1" and leave the height alone. With some additional bracing, it might be good enough, although the cast aluminum is a bit weaker when welded. I'll probably fab something new later down the road, but for now, it works for sizing and all."

                  In the 318ti N52 build thread: They mention using the stock mounts installed 180 degrees. The E36 subframe must be different than the E30 where the engine mounts mate, but it seemed they were able to take advantage of the offset in the rubber motor mount. The offset is about one inch.


                    Ah. Yes. Important variables to consider are that CWLO’s subframe is (I believe, correct me if I’m wrong guys) a modified arc-asylum subframe that previously accommodated his M54. He may already have been using non-m20 motor mounts, which I believe are part of the job for any m5x swap, although I don’t know those details. Sitting on my aluminum engine arms on 2x4’s to simulate motor mounts, on a factory e30 crossmember, both the valve cover and oil filter housing were touching the hood skin with the hood liner removed. There’s a picture a page or two back.

                    There’s a lot to learn from the 318ti build, but I would be careful following anything related to the subframe or suspension and steering component clearances. That actually goes for headers for both projects as well. The 318ti has an e36 front subframe and there are significant changes to accommodate the rear sump on the engines that were fitted to that generation. E36 motor mounts are already behind the ball joint.

                    Attached Files


                      You make some good points. Hopefully some others will chime in for some clarification.

                      I was under the impression that the ArcAsylum subframe was 'modified' to make it what it is, not that cwlo's subframe had been modded after the fact. What is it that makes that Arc subframe different, other than the smaller diameter cross tube that's pushed forward? Does it allow the motor to sit lower?

                      I bought an E30 front subframe on Ebay. When the subframe arrives, I'll be able to see better where things will land and what mods will be needed.

                      To be honest, I'm still trying to wrap my head around everything that needs to be done to swap this motor into the E30. I haven't done a motor swap before, which is why I wasn't planning to do it right away. Still much to learn.


                        Here is the other instance where someone (Saturnblau) has referenced the 1" dimension for moving the engine toward the firewall.


                        "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."


                          I’m not saying an inch is wrong, I expect that mine is somewhere around 1.5” back from where ever my arms would have landed over the e30 motor mounts. I was just desperately searching for another way to back-check my longitudinal position... which is just based on the shifter.


                            All I have to go on at this point is what 'you guys' are reporting. At some point hopefully, I'll have something significant to report as well.

                            I have a steel oil pan, so I was planning to modify it and make an aluminum tube to lengthen the oil pickup tube. I'll probably try to add back the volume lost, to the sides of the pan in the rear.

                            I actually don't know if an inch is correct. Maybe .75" is a better number? or 1.25"? I'd be curious to know what kind of clearance still exists between the back of the head and the firewall. It seems 'we're' trying to gain quarter inches in the front. Maybe the motor can sit back a bit further?


                              First post in a few years. I want to get back into an e30, my 135 is fun but it's not the same. The weight of an m42 with more power than an s52 is highly intriguing for an e30 project.

                              I am the engineering/quality manager for a tube fabrication company here in NC. I have access to a Faro arm, tube laser(s), CNC tube benders, etc... Obviously we have contacts with other suppliers for sheet and machined components.

                              How can I help?

                              First thoughts are to pickup tubes, should be no problem.

                              Second thought is a modified subframe. Iterating on arc asylum.
                              Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

                              Originally posted by TimKninja
                              Im more afraid of this thread turning into one of those classic R3v moments, where Pizza gets delivered.


                                RIP your inbox when hoveringuy finds out about you. He might already be in his truck eastbound.

                                My plan for the engine arms is to make them very similar to the factory m20 steel arms... flat pieces that define the geometry. I'm expecting to end up with a fixture for assembling pieces in the future (probably something that'll mount to my spare block) so there'll be an opportunity to reproduce the geometry with tube, but I don't see it being cost effective for this first pass.

                                What I'm very interested in with regard to a CNC tube bender is building downpipes. My plan has been to take factory N52 exhaust manifolds, hack them off below the collector (retaining the near-port O2), and V-band to a downpipe to connect to the factory e30 center section location. Someone was selling these for e90's at one point without much success as cat elimination (one of the attachments). I spent about 5 minutes confirming that my (I think e60) manifolds are a hopeless misfit for the chassis. There's some european factory manifold (the only attachment with cats) which has a little bit more of an equal length collector section, but certainly at the expense of space, and v-banding at the larger collector cross section would be an extra challenge. I've thrown an image of the supersprint type headers, which a few different companies sell. I'm not completely sure how these are supposed to work, because they move the near-port O2 sensor waaaaaaaay down and I'm not sure how that can work for engine management... It's a mystery to me whether the near port O2 sensors are near the ports for better sampling, or because the cats need to be closer to the ports to heat up as quickly as possible and that's the only place to put a pre-cat sensor...

                                All that being a preamble to say... If you have the capability to scan and bend what will undoubtedly be a hideous attempt at a pair of downpipes when I'm done, that'll be one of the hurdles I anticipate crossed off, and we'll end up with CAD documentation of the pieces so they can be duplicated going forward. I expect the pieces will look very similar to the e90 downtubes, but with no O2 bung (correct me if I'm wrong, Nando, just the near port O2 will be needed with the cat delete) and a V-band at the top instead of a weld to the manifold.
                                Attached Files