N52>e30 Build Thread for the Sophisticated Gentleman

[hubcapboy]

A very similar and boring process started on the starboard side. The bolt locations made a lot more sense on this side with respect to the motor mount, and this side was pretty easy to template.



I think these are @hoveringuy's fingers up top holding the cut-back factory manifolds while I muttered about how there was plenty of room to turn a front bank exhaust back over the engine arm... worst case maybe I'd scallop the top of it for a little more clearance... while he muttered back about how the factory manifolds suck and I was making a huge mistake. It was incredibly nice to be able to set the head on and off, mount the mainfolds, etc to check this stuff without having to lift the whole engine and transmission in and out.


I still think this early design is better if you aren't going to bother with the headers, but the header development came together at about the same time, so a revision to the starboard engine arm pushed the arm itself forward to wrap around the ideal routing for the front back collector



I don't have a great shot of that bracket holding the mock-up block in place, but this is what it looks like leaning over the fender from above with the engine away from you, and the lowest hole picking up the motor mount stud:



and here's both prototype brackets in the jigs with the final designs set to the side. These got a few coats of epoxy paint and sat around for a few months while I started on other components... but you might see either of these painted or unpainted in later photos holding one or other engine up while I worked on something else.



With these new arms bolted to the mock-up block and one more fixture to define how the engine rotates around the mounts, I was able to unbolt and grind off the fixtures for the not-a-sump... leaving me with the mock-up block sitting under the hood supported on engine arms and motor mounts, with clear space below to start looking at oil pans.

[hubcapboy]

There's a ton of controversy about how the factory engine arms work and how you should treat the magnesium block on the n52 discussion thread. I'll summarize some of it and my decisions here... you may come to different conclusions. As much as I can, I use "motor mount" to mean the flexible suspension between the engine and subframe, and "engine arm" to mean the piece that bolts to the engine block and transfers loads tot he top of the motor mount.

-The engine block is magnesium, and is generally isolated from steel parts by using rubber, plastic, or aluminum intermediate parts and gaskets. This is due to some concern that direct contact with the dissimilar metals will cause corrosion to the magnesium. I knew a little bit about this coming in... and for a start it didn't make sense that if the engine block was grounded to the rest of the electrical system, why it would make any difference at all whether the metals were in direct contact. Galvanic corrosion is electrical/chemical, and will happen any time two metals are conducting and exposed to the same continuous electrolyte to complete the circuit. If I had to guess, this would never be a concern if this engine weren't exposed to the elements, particularly salty winter roads. The countermeasures that BMW took in the assembly of the engine seem to me to just distribute the effects and if possible move corrosion away from surfaces that need to separate for surface... such as threaded fasteners, the oil pan, and ancillary brackets. The factory oil pan for an N52 manual is painted steel, and the gasket is detailed with a flange to stop salt water from making a short bridge between the materials... but there's aluminum pan bolts that will certainly scratch off the paint on the pan enough to make an electrical connection, and they thread straight into the magnesium. Building the engine arms out of aluminum to match the factory arms wasn't just vastly more difficult for me, it was unnecessary because there's going to be steel in the ground path eventually. A lot of it. The whole car. For my engine arms, I'm using an aluminum washer to give me a gap from the block and to prevent direct contact, and I'm painting my steel bracket.

-The bolts on this engine, wherever they engage magnesium, are aluminum. This is probably both to reduce weight and minimize the corrosion where a bolt needs to move eventually. The most important thing to know about these bolts is that YOU CAN ONLY USE THEM ONCE. This is not a joke, this is not a suggestion. Normal steel bolts are torqued, which is a measurement of how much force is applied to the bolt and at what distance, and translates to a tension in the bolt which holds the components together. In typical steel bolts (any of the ones that aren't labelled DO NOT RE-USE) this tension does not exceed the elastic limit of the bolt. The tension stretches the bolt, and when you remove the bolt it goes right back to its original length. These aluminum bolts, every single one on the engine that engages magnesium, are torque-to-yield. In the service manual, you'll see a torque, and then an angle. The torque gives you a starting point, but the angle prescribes an amount that you need to stretch the bolt beyond it's elastic limit. This plastic deformation means that you have a very predictable tension in the bolt after this procedure... but after it's removed it will not go back to its original length. If you try and repeat this process on the same bolt (after removing and re-installing) there's a very high chance the bolt will break. I tested this on four used engine-arm-to-block bolts, the big ones, and every single one broke about halfway through the specified angle. DO NOT RE-USE ALUMINUM FASTENERS ON THIS ENGINE.

-The mechanism for how the factory brackets transfer load is not really known... we haven't talked to the BMW engineers who designed them. Anecdotally, one of the bosses on the arm is rebated so that it "pushes" onto the engine block nub. It's a very shallow interface, and it's in cast aluminum. I think this is just for ease of assembly. I don't believe that these bolts see much shear force since they are torque-to-yield. Usually this type of connection is designed to be slip-critical, where the tension in the bolt is used to create friction between the mating surfaces, and that coefficient of friction along with the bolt tension is enough to resist the anticipated forces. I ran my aluminum washers over some rough sand paper to give myself some confidence there. There are also engine arms for this engine which only use 3 bolts (I believe the z4) so as long as we're sensible about placement, a bracket with four bolts will be adequate. The last thing to know about how the statics of these engine arms work is that the shape of the arm has absolutely nothing to do with how the load is distributed between the bolts on the engine block, provided that the bracket is sufficiently stiff (and in the directions we'd be worried about, mine are). The only factors in distribution of load are the direction, magnitude, and location of the force applied to the bolt group from the motor mount. The arm is a black box.

-There's tons of speculation about whether there's a factory engine arm that would work when combined with a different factory motor mount, or a motor mount re-drilled into a different location in the subframe, or a factory engine arm with some straightforward modification. I hadn't welded aluminum, don't trust welding of cast aluminum in this application, and didn't really have any way of testing every engine arm in my mock-up. I can say definitively that e9x arms would not be a good starting point, because the motor mount locations are out over the control arm ball joints for our car... the arms are just too wide. I still have a spare subframe and the loose engine block, so if anyone wants to see how a set of arms relates to the E30 subframe, send them my way.

OK. Here's my engine arms.

The factory engine arm is cast aluminum, and it's a pretty gossamer construction. You can see one rebated mating surface on the top right of the picture here, but all of the mating surfaces on the bracket and along the side of the block are flush. Cutting and realigning this bracket would be possible, if you could get over the challenges with welding cast aluminum, but I'd want to insert a plate between the two halves to do this, and you'd have to know the plane that you needed to move the bracket in advance. These brackets are now wheel chocks:



There are six mounting bolt pickups on each side of the block. I started off by taking a rubbing of these, scanning them, and cutting plates to match the "front four" and "rear four" on each side. I didn't know at this point where it would make sense for my arms to attach. The five holes in the middle were just in case I needed a later reference between an "arm part" and a "plate part," and thier location ended up pretty much meaningless. My goal was to design arms that defined their own geometry (slotted together with tabs or assembled with bolts, and could then be welded) but I wasn't successful. The final arms need to be assembled in a jig.



On the port side of the engine which is the "high" side of the block, I bolted my new e46 motor mount to the modified seat you can see in the early engine bay posts, and dropped a thick square plate the same size as the motor mount on the stud. I started mocking up arm shapes for the front and rear engine plate locations (you can see all six potential bolt locations here... if it's a bolt location that hasn't been used, they are tapped from the factory but I found that you'll want to chase it with a tap to clean up the threads that have had gunk in them for as long as your engine is old)



I used a ton of 3/16" craft plywood, hot glue, and paper templates, and learned that an arm that goes to the rear plate location will inevitably conflict with the steering linkage, and an arm that goes to the front location will end up being a very awkward shape, and will obscure the installation of at least the bottom bolt in the center. Mounting with three bolts at this odd angle wasn't ideal. If I was going to run the arm straight over to the block, it was going to be very close to the center two bolts, probably spanning them, and a four bolt plate would have been awkward. I went back and re-drew a 6 bolt plate and some of the pieces I'd templated out of plywood, and this was the first iteration I tested. The markup here is showing how I need to widen the arm to clear the bottom bolt (I wasn't sure if I was going to be able to warp the bracket to clear).



After making that adjustment, here's the final port-side arm being assembled in a jig that was created from the first attempt. These jigs aren't great, but I have the original prototype engine arms stored in them, so I can always make a new set.



We've assembled two pairs of engine arms from these patterns and both engines plopped right into place.

[Mazdayasna]

Very clever play with the not-a-sump! Looking forward to reading future updates. I recently bought an E82 128i and have really fallen in love with the N52.

[hubcapboy]

So much wiggling, checking what that changed, shimming again, checking to make sure it was still centered... One final check of the 24v lean angle:



And now, the not-a-sump magic. I have big ugly mild steel hanging down under the engine that I can lock off to the chassis. Way too fiddly to unbolt the block from the not-a-sump to lift it out, and no way to tilt the engine while it came out the top, so the fixtures had to be removable:



So glad I didn't decide to try and build my arms like this. With the fixtures unbolted, the engine package removed, and the not-a-sump swapped back into the car, we have a perfect negative of the block location under the hood:



It doesn't look like much, but I could stand on this. It absolutely represents the location and rotation of the engine as it was under the hood. If you're the kind of person who's been tripping over a bare N52 block in your basement for a year, you can carry it outside and bolt it in place:



Let's say you were also the kind of person who had a stripped N52 cylinder head and spare valve cover. You might as well throw that on to show off:



Look. at. all. that. room. You can see a few of the plates I'd pre-made to start mocking the engine arms up (this is why the block was in the basement). Since the shape of the engine arm is totally new and unrelated to any factory part, you can also see the e46 hydraulic motor mount that I decided to use. If these are good enough for the e46 M3, they're good enough for me, and if anyone wants to upgrade to solid mounts of any type, they're already made. Matching an older rubber mount didn't make any sense, and the e90 mounts are too large and a completely different design.

[hubcapboy]

Now that I could wiggle the front of the engine, here's the not-a-sump in place while I start lowering the whole thing into place to start locking down engine location:



After probably 3 weeks of wiggling and asking friends and doubting myself and putting hoods on and off and measuring, I ended up with "enough room in front to probably still fit a radiator"




And enough room at the rear to "probably still connect heater hoses without them hitting the 3-stage n52 intake"



Does this photo make it look like there's MILES to move the engine to the rear? It does. This next one shows how much cylinder head there is rear of the intake manifold, so it isn't quite as much as you think. Other things to consider are that moving the engine back this maybe-inch would affect the size of the oil sump, a redesign of the shifter carrier and linkage, and would move the engine down to avoid conflict with the transmission tunnel taper. It would also mean that the heater hoses no longer cleared the 3 stage intake and I later discovered would create a conflict between the 3 stage intake and the bosch electric booster. As long as I have room for a radiator, I'm not concerned about weight distribution because I'm losing a ton of weight in this engine swap already.

[hubcapboy]

Ok. This is the story all about how... I settle on an engine location and got it to stay there. All BMW swaps take advantage of the offset in engine and vehicle generations where and engine will span two chassis generations, and a chassis will get a mid-life engine update. The M42 was in both the e30 and e36, the M5x was in both the e36 and e46 and e85, and the N52 was in the e85 and e90. Because of these factory interchanges, we don't see vast changes in geometry.

When we try and locate the engine and transmission relative to the car, there are 6 degrees of freedom. There's translation along each of the three principle axes (forward-backward, port-starboard, up-down) and there's rotation around each of these axes. The more of these we can eliminate by making decisions, the fewer we have to scratch our heads about. The first axis I'm going to think about is forward-backward, because I think it's the easiest. This is an engine that came from an e90, so I think it's useful to see how the dimensions changed between generations:



One of the considerations when aligning the engine front to back is the location of the shifter. I started with a 330i engine package, and the shift carrier (the aluminum casting that spans between the transmission and body and locates the shifter ball) is common between the 1 series E81, X1 series E84, and all E9x 3 series variants. The length from the shifter to the front of the transmission is related to the distance between the hole we have in our tunnel and the firewall. Looking at how relative dimensions have changed with generations of the 3 series, it doesn't really look like the driver position has changed relative to the firewall. The front wheels shifted forward between the e30 and e36, but we know that was because the front axle and oil sump swapped places. I started off with the assumption that if the shifter position from the e90 worked, there was no reason to mess with it. Rotationally, we know that single cam 6's lean at 20 degrees (like the M20) and that 24v 6's lean at 30 degrees (M5x, N52). It's easy enough to measure this angle, so two degrees are locked down: Longitudinal position and rotation.

The translation in the horizontal axis (the line between the front wheels) is fairly easy to get a starting point. Motor mount pickup locations are symmetrical on both the e30 and e90 subframes from measurements of the motor mount pads vs the ball joints. If we mount the e90 engine arms to the n52, drop it under the hood of an e30, and wiggle it around until the motor mount bolts holes have equal distance to the frame rails... that's your starting point, and don't move it if you don't have to. Rotation around the horizontal axis (rotating the engine package around the line between the front wheels) is easy to make small adjustments to after the fact, because the motor mounts allow a few degrees of rotation. You can see the impact of this angle in a cross section of the e30:


Looking at the driveline, there's a slight declination to "point" the transmission output shaft at the diff input shaft. This doesn't give us much room to make decisions about this rotation. We have to match this angle within a half degree or we won't be able to correct it... and if we're wrong, we want to be on the upper end of our range at the back up the transmission so we can tilt the engine down a little further by shimming the transmission mount (adding spacers or washers between the crossmember and frame).

That's four of six degrees where we have clear guidance. Translation in the vertical axis is a compromise between the space between the valve cover and hood, and the space we have left under the engine for an oil sump. It's also critical to our driveline diagram above... we don't just have to match the angle of the driveline, we have to match the height, or there'll be a vertical offset at the transmission output. We don't have two U joints like a pickup truck to make-up this offset... This driveline isn't expecting the diff to be moving up and down. As long as we're pointed at the diff, and we have room under the hood and above the crossmember, vertical position is what it is. Rotation around the vertical axis is straightforward: Aim the driveline at the diff.

That's all we have to know to lock down the engine position. Now... how to build it... fabricating and welding engine arms around a fully assembled engine with plastic parts didn't seem like a great plan, and I only have one engine. I needed something disposable to mount fixtures to, so I built the not-a-sump:



This does two things: it lets me remove the rear sump that conflicts with the e30 subframe, and it protects the delicate underbelly of the engine from the environment and my prying and scraping. The lump at the front of the engine is just large enough to accomodate the oil pump, because if I don't have to take that off, why would I. Once the engine package is under the hood with the not-a-sump mounted, I can start jacking, shimming, and measuring. I left the e90 engine arms bolted to the block and gave myself a wood platform to sit on and slide around:



It was a huge pain moving the engine around while the transmission was supported on a jack or blocks on the ground, so I made a rough transmission mount first. The way the floor pan works, sliding forward and backward isn't a problem, and the location side to side is pretty clear... I can jam about a finger either side of the trans between the tunnel and case. We later found that the 325i and 328i have a much smaller transmission than the 330i, and it might not have been so obvious. With either of those donor cars, your factory e30 manual crossmember will work here:

[hubcapboy]

I need to pick up a set of those S54 headers before they get hard to find. It might still be a while before I get a motor built, lol - been working on rebuilding an OEM stereo instead.

BTW, when you get to starting the car, we'll probably want to to reflash the DME. it can be done via OBD, but we fixed a lot of stuff on Steve's car that we don't need to do again. Probably just baseline it off that, and turn the 3-stage back on.

Yep... start a list. I think they'll be around for a while. Factory M20 manifolds are still around. I have my early-version flash here ready for a first start, but I'm pretty sure you flashed two DME's for me to begin with, so whenever you have time to put together the files let me know and I'll flash the other one with the new and improved.

[nando]

I need to pick up a set of those S54 headers before they get hard to find. It might still be a while before I get a motor built, lol - been working on rebuilding an OEM stereo instead.

BTW, when you get to starting the car, we'll probably want to to reflash the DME. it can be done via OBD, but we fixed a lot of stuff on Steve's car that we don't need to do again. Probably just baseline it off that, and turn the 3-stage back on.

[hubcapboy]

WELL, that was the plan anyway. Unfortunately... This approach isn't perfect. The geometry on these primaries is great for the m50x air conditioning compressor location, but conflicts with the location on the N52. Scroll back up to those super fancy european headers to see how close this is and how the factory euro headers deal with it:



Given the option of changing the shape of the AC compressor and changing the shape of the cylinder 1 primary... I chose to chop out the problem runner and keep moving. These 2.5" to 2" reducers take the size of the union where it goes into the catalyst and brings it down to a more managable 2" diameter. Bank 2 here is tacked on, and bank 1 is taped on to check the angle of departure of the cone. The aluminum foil tape turned out to be super useful for mocking up and tacking tubing. It's fairly strong in tension, very thin, and super easy to scrape off and clean to be able to tack a few spots while the joint is taped together.



Cylinder 2 is the sticky-outest of the primaries, and just barely interfered with the frame rail. Post 12 in this thread shows the fix for this... here was the problem being discovered:



There was a lot of moving the front two banks back and forth between the engine block mounted in the mock-up car and the engine (which had the transmission mounted). The sleeved connections along side the transmission should give me some leeway when I go to re-assemble this in the car.



Once everything else looked like it was going to work, I went back and built a new cylinder 1 primary around the AC compressor. I don't have a ton of clearance, but it's probably as much or more as the euro... and I realized I've completely borked my equal-length math... but I wanted AC and wasn't starting over!



I just realized I'm referring to an engine block mounted in the mock-up car and I haven't gone through how it got there. sigh. It sounds like engine arm geometry and engine position better be the next update.

[hubcapboy]

OK. Updates on systems, and what was done to prep the engine package prior to dropping it into the engine bay shown above. This is going to be very boring for anyone who has been following the discussion thread, but a lot faster to absorb for people who haven't. In no particular order, the first is:

EXHAUST

This engine is pretty much the same shape as the m20 that came out, and pretty much the same shape as the popular 24V swaps, but there's no interchange-type header or manifold that will work for the combination of engine and chassis geometry. There are beautifully made (although not high production) headers for the N52 in the e9x chassis, but I wasn't able to locate a set at anything below full retail for experimentation. There's even a company in Australia making a set of beautiful headers for RHD e9x's. Considering the questionable clearances and hammering and twisting that I understand are needed to fit m5x 24v headers in the e30, and the n52's cylinder head being considerably wider and moving the exhaust ports further... starboard... All of these aftermarket N52 headers look to me like they go straight through the e30 control arm bushing, if not the frame rail, if not the passenger footwell.



The first option for an exhaust solution is the easiest. Every factory north american n52 comes with very, VERY compact exhaust manifolds with a boss for the only O2 sensor you need. There's two banks of 3, just like most BMW 6 cylinder systems, and they're identical after you cut off the catalysts. Sourcing them unless you have a complete donor car is a *little* tricky because the catalysts themselves are regulated, but there are yards that are happy to cut them off, and they're plentiful. This piece goes in the recycling bin at every wrecker because they come off with the catalysts.



There's tons of room to work out how to Y these together, and I think they'd look and perform fine. If you *really* want to do some math, there's ideal distances for the union to control exhaust pulse timing between the two banks, so don't think that just because the manifolds just mash three cylinders together that you can do the same as close as possible with no ill effects: the 6 cylinder firing order alternates between the front and rear banks.

The next option is my golden goose. There ARE factory manufactured equal-length short tube headers for the N52. It's totally unclear to me which models they were fitted to, and they seem to *share a part number* with normal looking 3-into-1 manifolds depending on which european country they were delivered to... I don't trust images on realoem or other fiches to correctly represent what these manifolds look like, but I have seen 2 sets for sale in europe and russia. Since these also have catalysts attached they're even more complicated to bring into the country. Many hours were spent lying awake thinking about these headers.



This makes me think that BMW saw some value in developing and manufacturing the short-tube headers where they could get away with it, and figuring out some type of equal-length header became a priority. Custom headers cost as much as my entire project (which ain't nothin) so the answer became "adapt s54 headers to the n52." These headers are EVERYWHERE in the US... and they're *cheap* due to the number of people discarding them to replace factory manifolds with long-tube aftermarket headers without catalysts. This is $40 worth of hard to make parts from an S54 Z3M:



And here's what they look like after you slap your forehead and realize the bore spacing is the same, make some little tube extensions in the right diameter, and cut flanges to match the N52 manifolds:

[hubcapboy]

I'm still here!

I'm one update behind, (spoiler alert... the engine package is IN) and I've been meaning to come back with that update. Thank you for the reminder.

I've been doing most of this work outside while my silver car snoozed in the garage, and my goal going forward is to continue the work in the garage... which means I've had a ton of workspace cleanup eating my time. "here's how I sorted all the half-boxes of nails and screws I moved to this house 2 years ago" isn't the most riveting content for the thread :)

Edit: Remembering now... the delay in the update is because I'd hoped to detail the steps taken to prepare the engine package before I just show it plopped in... and that involves me sifting through the other thread to remember!. I'll get right on it.

[Slybeanx]

Good thread, just needs an update :p

[nando]

It's lachssilber. I thought I might be painting the engine bay, but it all seems pretty clean. I just scrubbed it. As far as a paint match on that frame rail... ugh. The high temp paint is probably better next to the header.

ah, duct tape silver.. I think there are some close matches for that (such as duct tape, lol) but I haven't owned one in that color since my parts car.

[hubcapboy]

Awesome updates.

In regards to the radiator mounting, would a late model be better, or is it a moot point either way due to the radiator used?

I don't think I'd choose a late model for the swap just because of the radiator mounting brackets, but it's one less thing to do if you have a late model. This rad should fit late models, and thus other late model rads should fit this down the line if I need to swap it. My car is an early, the mockup car was an '88 (transition) and the other N52 swap that hoveringuy has completed is a late car. We didn't run into any huge advantages of one revision over another.

[hubcapboy]

It's lachssilber. I thought I might be painting the engine bay, but it all seems pretty clean. I just scrubbed it. As far as a paint match on that frame rail... ugh. The high temp paint is probably better next to the header.