N52>e30 Build Thread for the Sophisticated Gentleman

[lukeADE335i]

It's not my goal to turn this into a career (if you can't tell by how driveway-science this looks) but I am on board with hoveringuy with the goal of standardizing this engine as a swap (and broadening it to a potential swap for the ix). It's getting more and more and more likely that I'll figure out a way to open-source the information so anyone can reproduce it., but I want to at least get my car finished first A few people have reached out to see if they can start production, but I think it's too unproven for someone to sell this and expect people to be able to follow a guide.

Open source would be awesome - no, I wasn't thinking you'd be turning into K-Miata or something

Basically that was how I did my M30 back in the day - there were no swap guides outside a brief description of the swap on e30.de back then and a few r3v threads. I grabbed engine mounts from e30.de and went for it. Obviously this is a lot more complex than the M30 was!

[Northern]

I think that was a joke about the girth of the oil pan flange lol

[hubcapboy]

Great work on documenting your swap! With so much work on the engine arms, sump and oil pickup etc. do you intend to sell a kit at some point?

It's not my goal to turn this into a career (if you can't tell by how driveway-science this looks) but I am on board with hoveringuy with the goal of standardizing this engine as a swap (and broadening it to a potential swap for the ix). It's getting more and more and more likely that I'll figure out a way to open-source the information so anyone can reproduce it., but I want to at least get my car finished first A few people have reached out to see if they can start production, but I think it's too unproven for someone to sell this and expect people to be able to follow a guide.

Does the oil pan substitute as a block girdle also? Looks like it'll be ready for war. :)

Funny you say that. block girdle... no, as nando says above, but the 2nd revision of the oil pan that's in hoveringuy 's car you'll see if you poke through the discussion thread was built up with laser cut pieces in a heavier gauge to forgo a skidplate. With the streets around here, I don't want to know that every time I hear a clank it's shocking my whole driveline.

[nando]

Block girdle? the N52 has a bed plate, so the main caps are cast into the lower half of the block itself. it's waaaay stiffer than an M54 block with standard steel caps.

[moatilliatta]

Does the oil pan subatute as a block girdle also? Looks like it'll be ready for war. :)

[hoveringuy]

Great work on documenting your swap! With so much work on the engine arms, sump and oil pickup etc. do you intend to sell a kit at some point?

I hope so, and if he does I can tell you that I've been working really hard to find any engineering deficiencies. It's been rock solid after a full season of tracking, and my feeling is that the more people that get the N52 the more we can innovate and gain from shared knowledge!

[lukeADE335i]

Great work on documenting your swap! With so much work on the engine arms, sump and oil pickup etc. do you intend to sell a kit at some point?

[Trevbot]

Every time my brother comes over to sip a beer and look at the car he shrugs and says "you know you can buy this engine in a 1 series... right?"

I got sick of waiting for you to finish and tried this engine and transmission in a Z4 coupe. It wasn’t a big enough upgrade to replace my FRS, but what if it had a back seat and lost 500lbs… 🤔

[hubcapboy]

All the pieces I've drawn or templated so far just made sense and fell into place. I'm a little more proud of this one. Similar to the pressure to adapt headers, I was starting to hear rumbling about how all track-bound BMW's need an oil baffle, and that without one rear-sump cars get oil starvation under braking, and all cars get oil starvation around long right hand corners. I'd thought about designing the entire pan around an available drop-in baffle, but after thinking about what a baffle actually does, and staring at a few hundred examples... it seemed like pretty much everyone was just guessing based on a few common concepts. Oil should be able to go into the baffled area but not out unless it's deep enough, oil shouldn't be able to go from one side of the sump to the other without passing through and filling the baffled area, and oil draining from the engine should ideally drain to the baffled area and then overflow to the rest of the sump. Many aftermarket baffles use hinged plates, but the ones that interested me the most were based on Cosworth style flaps:



These were actually used in the original factory e30 M3 baffle, and are part number 11131309428. Don't look too closely at the price. I think this type of trap door is better sealing, quicker-acting, and less error prone than a metal flap with a hinge, which is going to constantly wear and shed metal, and could get stuck.



Taking all of this into account, this is what I came up with:





The oil pickup will drop into the baffled trap, and the flaps will allow oil to flow into the trap under left hand turns or acceleration, will keep oil in the trap under braking or right hand turns, and the trap will be constantly filled by the tray from the rear of the engine and the top-plate, which collects oil from the front of the engine and forces it into the trap until it overflows through the holes along the top of the trap walls:

[hubcapboy]

There are a few other components that need to go into the oil pan, such as the drain for the PCV system, which you'll have if your engine is a magnesium valve cover. I just cut this off the factory steel oil pan and moved it over to the same location on the new oil pan:



And the oil pickup, which is made from a very standard DIY chevrolet V8 pickup kit, with a steel adapter turned to fit the oil pump. The turned steel piece that fits into the oil pump matches the geometry of the plastic pickup, and even uses the same O-ring:



Setting that at the correct angle and at the correct height for the bottom of your sump lets you build a little bracket to hold it to the windage tray bolts:



Another issue that came up during construction here: I sized the tray around the factory windage tray that's bolted up to the bottom of the block bedplate... but didn't consider that the crank counterbalance at the rear actually comes VERY close to the inside face of the engine block - off the end of the windage tray. hoveringuy discovered this while rotating his engine, and mine cleared, but I checked it with putty anyway:



and I eased the edge of the gasket flange just to be safe:

[hubcapboy]

One side of the pan was left open so that I could size up the best way to build an oil pickup. Here's a similar angle to the plywood mockup, but this is my tacked together pan bolted in place. You can see my paper template is still glued to the inside of the pan for some reason:



The skidplate is in place, and there's enough clearance for a rock to fall through. Here's where the rear tray section overlaps the sump to (hopefully, one day) let the oil drain forward:



And here's what that tray section looks like looking forward from the transmission:



At this point I decided this ugly piece of crap was good enough to finish instead of throwing away as a prototype, so I improvised a method to remove the paper templates:



I'd already drawn and cut a doubler plate for the oil level sensor, and I drilled and installed a bung for a dipstick:

[hubcapboy]

The goal for mocking up the pan in plywood is to give me something that I can tear apart, trace, and refine, and eventually draw in CAD to be able to cut. I'd like my pan to have around the same ground clearance as the factory m20 pan, because after seeing a few e34 pan engine swaps it's very concerning that going that route reduces groud clearance even further. A good guide for this is my M20 skidplate, which has plenty of battlescars from driving around the city, and which an e34 pan doesn't fit inside of:



my markups here are showing that I have a little way to go back, but you can see in the background that the gear on the steering rack prevents me from going back much further. In order to get the skidplate to lift up into place, I need to either bevel or severely cut back the front of the sump.



This is just the sump "wing" sticking out to the side. I made it as long as I could, and it actually goes past the edge of the M20 skidplate in the prior photo, so I do have to cut or grind down the vertical return on this side, but it seemed like a reasonable compromise. The top of the wing can't come up much further and hold oil, because the oil level would be above the pan gasket on the starboard side (don't forget the gasket is at a 30 degree angle along with the block).



This is the view from the front, and you can see that the left "wall" of the sump comes straight down parallel with the engine lean. There's a ton of room on the starboard side for extra oil volume, but extending the pan in this direction leads to challenges with installing the pan bolts. Some pans do use through-bolt or long bolts with reinforcement through the pan to do this, such as the VAC Motorsports pan for the M10/S14:



As an aside, I would have loved it if I had some practice tig welding aluminum, and when I get around to it I could easily adapt the pan design I ended up with to this type of construction... but the expense of farming this production out was too much compared to the ease of cutting and welding steel. After messing with plywood and hot glue, measuring, drawing, printing, gluing my templates to some plate I had lying around (too impatient to wait for laser cutting) bending, and tacking, I had this:

[hubcapboy]

So we know we're going to kinda build something that looks like the above pans, but out of flat pieces of steel bent or welded. The most complicated and precise piece of this is the flange that needs to mate up to the bottom of the engine block. This came in two types on the factory engines: a beefy aluminum casting with aluminum bolts, and a flimsy steel pressing which came with the same bolts, but with a spacer the same thickness as the aluminum flange pan (so that the torque-to-yield aluminum bolt can be the same design). We're building a steel pan, but I'm going to use the same thickness steel for my flange as the aluminum pan. This way I can use the bolts intended for the factory aluminum pan (without the spacers) and they'll perform correctly. Here are the bolts for a thin flange:



And here are the bolts for a thick flange:



Note that I need *more* of the short bolts than are provided in the aluminum pan kit - mine are all the same. I bought two kits worth of the bolts without the spacers and thew the longer bolts in a drawer (they're actually the same size as some other bolts on the engine, so don't throw them away).

To make a flange, I flipped my engine block upside down and stared at it for a while. Then I ordered a flat bed scanner and a new oil pan gasket. I scanned each segment of the gasket with the flatbed:



Then I re-aligned them all in autocad:



and then checked a few key dimensions against the block to make sure I hadn't warped or stretched anything. After laser cutting the drawing to the right thickness, I had a flange for my oil pan:



With this bolted to the bottom of the block and the block supported by the new engine arms and motor mounts, I can warm up the glue gun and start mocking up an oil pan.

[hubcapboy]

OIL CONTROL

If you haven't poked around under your e30, this is what the oil pan looks like from the front:



and if you haven't held a loose pan in your hands (actually, I haven't), this is what the rear half of the pan looks like before that sump drops down:



And here's what the e34 oil pan looks like, which is the magic 5 series pan that lets us install all M5x's up through the S54 into an e30:



This pan only exists because the e34 5 series was released as a front-sump car in 1987 with an M20 just like the e30, and later got upgraded to the M50 when that engine was developed. From a "what do we do with the oil" approach, this is a pretty simple geometric matter of making a shallow tray that drains to the front on level ground (despite the engine declination to the rear), and incorporating any other features that we might want into the new pan. An e34 pan doesn't have the e30 oil level sensor (I think it has a different one? dunno. don't care) and an N52 pan doesn't have a dipstick. I want both. Another concern I had early on is why on earth the e34 m50 pan looks like this on the bottom:



What the frik is all that gusseting to the flywheel cover for. Typically this is a separate piece of pressed steel and does nothing but barely keep the dust out. I'm pretty sure that on the M50, which was (other than the e34) expecting a rear sump, the transmission to pan bolts are very much part of the engine/transmission package structure. Very early on this was a big worry of mine when trying to hack together an oil pan for a late model bmw engine. Luckily there was a miraculous design change between the M54 and N52 which completely addresses this.



Rather than using individual bearing caps on the crank and hoping to stiffen the block with a cast pan, the N52 uses a 2-piece block. The upper casting holds the cylinders, and the lower casting holds the bearing caps, and the crank is sandwiched between. Adhesive is injected between the two to seal them. This is one bullet point on the long list of amazing features of this engine, but it means that manual transmission, RWD N52 cars (like my donor) were delivered with cheap, flimsy, pressed steel oil pans that look like an afterthought compared to this bananas engine block. This really simplifies what we have to do with the pan design, as it only has to be strong enough to hold oil.

[hubcapboy]

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.

Every time my brother comes over to sip a beer and look at the car he shrugs and says "you know you can buy this engine in a 1 series... right?"