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Old 04-05-2017, 03:51 PM   #1
e30WithNoWheels
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1986 325e s50b30us swap

Hello R3vlimited

I am a noob to BMW's, have done swaps in japanese cars before but never a euro. I have always loved e30's though, and now I am finally buying one this weekend. I came into enough cash and luckily found a great deal on a 1986 325e owned by a friend that has had multiple e30's in his family. The car is a great deal and I am buying it. That being said, it does have a mechanical issue from what I understand and that is fine with because I intend to do a engine swap asap. I have already done quite a bit of research, and I know that almost any question I have has already been answered. So I am posting here today to start my build thread and ask a couple questions that I have about the swap itself before I start throwing money around. First here is my current list of parts that I have sourced and intend to purchase:

1) s52, found 4 different units, help me choose (e36 m3 for $1400 with 190k mi, '99 z3 m for $1800 with 160k, e36 m3 for $2000 with 149k miles, or e36 m3 for $2300 with "obd1 intake manifold conversion" and 138k) all have compression tests done before purchase and will include harness.

2) e34: oilpan, dipstick, dipstick tube, oil pickup tube, throttle cable

3) Porsche 944 brake booster

4) e36 engine mount arms (If I buy z3 motor, otherwise will be included)

5) e28 535i or m5 engine mounts

6) 3.73 lsd ($250 a good price?)

7) garagistic "E30 M50/52/S50/52 GT260 TRANSMISSION SWAP BRACE"
and "BMW E30 M50/S50 WIRING HARNESS ADAPTERS"

8) Headers (???)

9) Exhaust: Car has "New stock exhaust" according to my friend selling me the car

As of now, this is my list for what I will need to actually turn the key and hear the sweet sound of that inline 6.

Questions:

a) From my research, it seems that I will be able to use my stock transmission and driveshaft, since I have the 325e, will my stock diff work temporarily? Will the driveshaft or transmission need to be removed when I am doing the swap?

b) What will I need to do with my radiator? I can't find a clear answer (I am going for absolute bare minimum for my budget).

c) What ECU will I need?

d) What will need to be done for headers/exhaust?

e) any other parts I NEED to turn that key and hear boom?

f) What should I do for OBD I conversion? I am confused if I need to do it or not, or if I can/should do it myself.

g) I would consider m50 swap with some good reasoning. I can get a motor for 1/3 the price

I live in California , so am also curious about emissions.

I will post pictures as soon as I buy the car, engine, parts, everything. I am very excited to see what the e30 platform has to offer! Thank you for any comments/answers/support of any kind in advance!

Last edited by e30WithNoWheels; 05-09-2017 at 06:34 PM.
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Old 04-14-2017, 01:55 AM   #2
sweet3
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Welcome to the e30 group!
A) It is much easier to do the swap with the tranny already bolted to the engine when you're dropping the motor in. Also, the driveshaft can be put on afterwards (before the exhaust is put back on obviously).
Your diff will be fine for now. It will have the same gearing as it did before if you keep the same tranny. Diffs usually only need to be changed when using the e36 m3 ZF trans. Otherwise, it's just personal preference.

B) For the radiator, I assume you meant 89 325i? I kept my same radiator. Original m20 325i radiator with the external coolant reservoir near the ABS module.

C) If you go with OBD1, you would want the red label DME that ends with 413. You could use a silver label 413 DME, but you would need to have EWS removed (same for any obd2 as well).

D) you can use the s52 headers, but you need to have custom exhaust work. Find a pair of flanges that mate up to your headers. The exhaust shop will need those.

E) The engine will fire up without a custom tune if you run an obd1 setup with the red label ecu. But you will definitely want a custom chip to get the most out of the engine.

F) OBD1 conversion can be done easily by yourself. Find an m50/s50 engine harness, intake manifold, red label DME, coil packs. There are a few writeups about this.

G) No good reason to go with the m50 over the s52. Only the price would be the benefit. In the long run, you will regret not going with the s52. It's a lot more fun haha

About emissions, I can't speak for that section. However, I've heard that some places don't allow the obd1 conversion. Unless ou can disguise it well enough by changing the valve cover too.
I'll let other R3v members confirm that.

Looking forward to seeing your progress, good luck
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Old 04-14-2017, 02:04 AM   #3
sweet3
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Oh, and to help you decide which engine to get out of those 4, I would just go with the $1400 option. You can do the obd1 conversion for less than $900.

$250 for a 3.73 lsd, that's a good price. But do your inspection on it if you can. Are there any leaks? What is the history? Etc..

To save a little extra money, take a look on the forums about the brake booster. You can keep your original booster if you move it over 1/2 in to the driver's side. There is a writeup about it on here
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Old 04-20-2017, 07:28 AM   #4
Bimmerguy91
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If you are using the G260 transmission I don't believe you need to change anything about your transmission mounts, brace or driveshaft. I could be mistaken but I believe that is correct. I have only done the conversion with the ZF320 transmission so I don't have first hand experience in that category.
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Old 04-21-2017, 03:14 PM   #5
sweet3
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The ZF trans can use the original mounting bracket for the e30 chassis. But the g260 sits at a slight angle when mounted to the 24v motors. So you'll need a custom bracket if you use the g260.
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Old 05-09-2017, 06:28 PM   #6
e30WithNoWheels
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Quote:
Originally Posted by sweet3 View Post
The ZF trans can use the original mounting bracket for the e30 chassis. But the g260 sits at a slight angle when mounted to the 24v motors. So you'll need a custom bracket if you use the g260.
Thank you for all the tips. So I actually have been able to source a s50b30us out of a 1995 m3. From what I understand that will help me save some headache with wiring and emissions. The seller of the motor has the car complete, so what other parts do you recommend I get of the m3 other than "complete motor with harness, intake manifold, injectors, coil packs, and vacuum lines" (seller).

-Vince
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Old 05-09-2017, 06:32 PM   #7
e30WithNoWheels
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Here are some pics of my new baby

1986 325e 156,000 miles working odometer
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