Insert some plastic here. The m52 swap.

posted in: Just e28 stuff | 1

Once upon a time there was a really smart Audi commercial.

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Everytime when i have to explain why the m52b28 is the most epic 6 cyl non S (///M) engine, I’m thinking about that advert.
Simply said the m52 combines all the good qualities you might look for, in a N/A engine.

The “technical updated” version is slightly better for a daily driver, because its equiped with the dual vanos which is improving the low rpm torque and maybe it’s probably a liiiiiiiiiiiiiiitle bit more efficient than the ordinary m52, but it’s complicated.
M52 on the left, M52TU on the right. Obvious differences are the inlet manifolds and VANOS plastic covers.

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For example every TU motor  is having that DISA valve, which is really pain in the arse at some point.
It got Four (yes, four) oxygen sensors and if just one failed, you are going to have a bad time.
Also most of those engines are equiped with electrical accelerator, which is another issue because in one hand you need to modify things to get it fitted while swapping (including extra wiring) and in the other, adding a cruise control  (CC) and having proper idle while AC is on will be another problems you’ll have to face.

And here comes the good, old, single VANOS m52b28.

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It’s reliable and  efficient. Spares & consumables are affordable. It got plenty of hp / torque. Some easy mods are available to squeeze out some more power (I’ll talk about that in the next chapter) and if that’s not enough for you, some forced induction can be held aswell (Comming soon in the chapter after that) . It got no DISA, just 2 LAMBDAs, CC is just a matter of attaching the bowden cable to the throttle body (if you already have CC) and no issues with AC idle.
Top of the pops.
It’s the engine that turns gas into smiles per hour.

Choosing the right еngine.

M52 is available in few BMW models. e36 328, e39 528, e38 728 and z3 2.8.
Now here is piece of an advice. Do yourself a favor and look for less abused engine.
I mean the m52 could handle lot of stress, flooring, redlining and stuff, but you know .. “You better be her first.”
Picking an engine from e38 728 with an auto tranny seems a way better option than having it from an e36.
With a LSD. Previosly owned by a teen.

In this particular article, I’ll be writing about swapping m52b28, taken out from e39 528i 98′ with stick shift, into an e28 that was originally equiped with m20 & stick shift.

Еssentials.

Make sure you will have the complete engine with all of it surroundings such as alternator, starter, hidraulic pump (steering), ac compressor, fuel rail, injectors, inlet and exhaust manifolds, throttle body, maf sensor, oxygen sensors, complete engine harness, ecu, immobilizer + connector, transpoder key ring & the chip from inside of the donor car key, flywheel, clutch plate, pressure plate, gearbox (look below) , mechanical fan  (they are pretty much same for all of the bmw engines, so take it only if you have a chance) …

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Or in other words, everything except the radiator, air filter box and engine mounts (right time to say, they woulnd’t work for e28).

1. Oil pan. 

Since the oilpan collector of the e28 engines is placed infront of the front axle and e36/e39/e38/z3 oilpans are behind it,

(e36/e39/e38/z3 on the left, e34 (needed for the swap) on the right.)
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you got only one option here  – Sourcing an oil pan from e34 m50b20/5 (m52 and m50 oilpans are the same, difference is only in the collector positioning). You will need also the e34 m50b20/5 dipstick and suction pipe from the engine – #6

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Oil pan gasket 11131437237 

Oil pan and suction cup replacement takes about an hour, and it’s nothing more than unscrewing and screwing back few bolts.
The little tricky part is the oil deflector thing. On m50 is attached via rivets to the oil pan. On m52 few bolts are holding it under the crankshaft – you will be able to see it, once you remove the original m52 oilpan. So simply remove all #2s till #1 is free to go and then throw it away. You wouldn’t need it.  Then just put the new oil gasket on and bolt back the m50 oil pan – it got the exactly same oil deflector right on it. 3d5h
The little trick here is, you need to cut off 25mms of the right side of the deflector on the m50 pan.

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That will grant some clearance needed for the fit. The deflector (yellow arrow) will drop with few milimeters below the oil pan frame (red line). Degrease and clean well the pan after that. You don’t need any alloy dust in your lubrication system.

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2. Accelerator bowden cable.  e36 m52 bowden cable is required It doesn’t have to be brand new. You can use the e38 and e39 cables, but the e36’s cable is just with the right lenght for your needs.

3. The Gearbox and the driveshaft.

Now, let’s make clear first the fact that ALL m20, m40, m42, m43, m50 and m52 еngines are with same gearbox bolt patern which basically makes the transmissions interchangeable, no matter if they were made by Getrag or ZF.

But … there are few differences.

№1. The m20 engine is tilted to the left with 10 degrees compared with the other listed engines. So if you are trying to fit m20 gearbox (complete waste of time and money according to me and gearbox ratios below) to any other engine pointed above, you’ll need to do two things – fabricate custom gearbox mount support and custom shifter, since it have to be twisted a bit ( or your 1st gear will sit on a position where normaly will be the 5th gear).

№2. The gear ratios. Here is a chart for the different engines.

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 The ZF and the Getrag.

Basically all gearboxes in the chart above are made by Getrag, except the m20b20, m50b25 ( e34 btw ) and m52b28 (which are using ZFs). There are rumors on the web, which are claiming ZF boxes are stronger than the getrags and could handle more hp and torque. We can’t confirm if that’s true or not, but on this particucar case (my swap), the getrag 220 (m43b18) is doing great so far. (FYI abusing the clutch at high speeds is what kills the gearbox)  The factory ZFs applied to the m50b25 in e34 and m52b28 in e36/39/38 are using larger output flange, which is slightly bigger than normal. Respectivelly the stock driveshaft flange and the guibo are slightly bigger (left) than normal too.
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Good news are the m10 and m30 gearboxes are with the larger flanges and guibos, so basically if you decide to go with  the original for the m52b28 ZF gearbox, you will need to source an m10/30 driveshaft (and bigger guibo too ofc.).

If you decide to go with a Getrag, which will be reasonable since they are easier to find, cheaper and also strong enough to handle the m52b28 power, your stock m20 driveshaft will fit plug and play and you will be ready to go in no time.

Picking a gearbox is totally up to you, but if we have to make any sort of conclusion:
If your goal is a totally trackday/drift e28, you better find a ZF.
If you are going for a pumped daily, good for a spirited driving from time to time, they you should be fine with a getrag.

e28 m20b20 gearbox support frame works fine on the getrag 220.

4. Gear shifter.

I used a linkage from e36. Fits great.

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The e36 rubber boot (#8) fits also.
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The only thing you need to do is simply grind the tiny rubber bushing with the bracket from any e36 and weld it to the e28 chassis after you adjust the shifter.

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5. The cooling system.

I bought brand new radiator for 6 cyl e36 with an AC. e36s equipped with ac got slightly bigger radiators
The black arrow points the difference.

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Besides of the precise fitment, its good because of few more reasons:

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1. The expansion tank is integrated in it and that saves some space.
2. It got that thread on the side for a temp sensor which triggers the AC (or the additional) electric fan.

( I made a custom frame for the e36 ac fan )

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3. Since the m52 is a common engine for an e36, finding proper hoses isn’t much of an issue for this swap.
4. e36 fan shroud can be used.

(I used an old radiator for a test )

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Secured it to the mask with a bolt. grommet and a fancy nut.

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6. Air filter

You might be able to fit the original for the m52 airbox into the e28 bay, but the easiest way is using a cone filter. Period.

7. Powersteering and A/C.

You will need someone experienced in TIG welding to get that done, since pipe customization for the A/C is a must.
A/C compressor intlet and outled threads are with a totally different angles compared to compressors used on m20 and m30.

Because of the same reason you will need to customize the powersteering hoses, also the one for the high pressure should be expanded with 90 mms. (if we take the m20 high pressure hose length for a base)

8. Exhaust.

It’s a totally a custom thing. What i did is just simply copying the curves of the OEM e28 exhaust, converting the whole system to a single pipe using a center and rear mufflers.

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Exhaust engeneering is really a thing, but let’s just say if you are going this way there is a simple formula. The diameter of the single pipe should be 120% of the diameter of one of the dual pipes. So in my case both of the oem pipes for m52b28 were 50mms, so i converted them to a single pipe with diameter of 60.3 mms.

9. The engine mounts.

This is the last and most important thing for the mechanical part of the swap.
Once again – there isn’t any combination of the oem mounts which allows you to fit m52 into the e28 bay.
So it’s custom again. After a lot of trials and errors we have our perfect more-modern-engine mounts kit.

If you choose to fabricate them by your own, here are few hints:

They have to  :

– Clear the servo unit. Most people prefer to use smaller units sourced from various cars, but the stock one is just great if you did it right.

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– Lifting the engine , so you don’t have to worry for the oil pan clearance anymore, but not too much so you will have enough space left for a strut bar.

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– Proper vertical  alignment. Otherwise engine will be tilted, which will cause stress over some details and that will lead to prematurely wear of some/all rubber components such as engine rubber mounts, tranny rubber mounts, guibo, drivetrain support. The other benefit of the proper alignment in my case is the the posibility of using an e36 fanshround (on the e36 radiator) without any modifications.

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– Proper horizontal alignment so you will have enough space for the stock or aftermarket headers, but not too much or it will affect the gearshifter positioning.

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10. Wiring.

Now this is the “messy” part of the swap. If you aren’t experienced in the electrical stuff, i suggest to get someone who is. Anyways I’ll try to explain it as simple as possible – dummies style. As i said, this swap is based on an e39 m52, so if you are using engine from another model, connectors is quite possbile to be different, different wire colors, pin relocation etc.,  so you will need to google some electrical documentation for your donor car and make your own conclusions.

The e39 engine had this two connectors. X6021 (11 pin) and X6011 (26 pin)

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Also you should have the EWS (immobilizer) module connector

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On the other hand there are 2 connectors on the e28 electrical installation.
The C101 connector (red arrow) which connects to the side of the fuse box ( yellow arrow)
( best thing to do would be to cut it off from your old engine)

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And the C103 which is located just behind the glovebox.

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* The speed signal is important. Without it the engine WILL run in a limp mode causing rev limiter to drop down to 5.3k rpm.Rumors over the web says that you have to connect this pin to the brown/red wire, which is located on one of the three connectors on the gauge cluster, but probably this will work if your engine is from e36 or z3 since they got their speed signals from the sensor on the differential cover (same as e28). e39 and e38 are using can bus signal from the abs module and most likely it wouldn’t work this way. Anyways I skipped this part with the hinting and just gave the ecu to a guy who modified it and the signal wasn’t needed anymore. Solved.

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Don’t forget to wrap the chip from the donor car ignition key arround the transpoder ring. This can be solved too with an ECU modification. It’s called EWS delete. The m52 ecu fits nice and clean on the place of the stock ecu.

The last  wire-related thing, concerns the temp gauge on the dash. The m52 uses one temp sensor. It sends info to both of cluster and the ecu. The sensor and the donor dash works on totally different resistance values, so you need to put the temp sensor from your old engine. Most m52s got tapped spare hole on the head where it can be placed. It wouldn’t fit like a charm, since the old bmw sensors are way bigger, so you need to do a custom adaptor. (We can supply few i guess.)

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After you bolt the sensor, you just need to wire it to pin #4 of the C101 connector and your temp gauge would work with the new m52. If we can put everything in one picture, here how look the m52 swap into e28.

 

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The differential ratio selection instead of final words.

e28s are using 2 types of differentials. typ188 and typ210 and any of those can be LSD ( Limited slip differential, kind of magic that makes the car sliding easier, doing 1/4 mile better and allowing you to enjoy the RWD in the winter ) That means the diameter of the crown gear inside of the diff case is 188 or 210 mms. All e28s except 535 and m5 are using the typ188 and the rest are with typ210.  Both of those diffs are having same input flange, so whatever you pick as a gearbox and driveshaft will fit your differential. There is plenty of info writen on the web about the gear ratios and how they affect the acceleration and the top speed, we might spend some time discussing this in another blog post, but for now let’s just say you might concider a different ratio diff after swaping the b28. Another good news are most of the e36s and e34s are using typ188 and there are so many options about gear ratio select. Anything from 2.56:1 to 4.45:1   . What suits you best. It’s a matter of a personal choice.
We could supply almost any of them, just shoot us an e-mail, revealing your most sacred gear ratio desires.

Bonus: Inspirational gif.

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One Response

  1. hi. just want to know. is it alot of work to do n m50b25 swap in a e30? thank you.

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