SWAP Thread: '91 325i Sedan - S50b30us

[hwy84]

I've had 4 E30s, and I have loved the fun handling of all of them. I've had 2 E36 M3s and I loved the motors. I had an S52 M Coupe, and it was juuuust riiiiight... except it had too few doors, and too many miles.

I wanted a 4 door M Coupe with a few less pounds, and less "irreplaceable" sheet metal so I could actually park it and not worry. Trailing throttle oversteer, decent torque, and enough horsepower to get into trouble. As we all know, there is only one way to do that...

...and thus was borne the "M Crap!" The handling and motor magic of an M coupe, but at 1/10th the budget. Hopefully. Maybe. Probably not.

In any case, this will be my swap thread, with pics, details, and questions for you experienced swappers, if and when I run into issues. I've read the threads, the wiki, and this forum for months as a lurker... I think I am ready. I hope I am ready...

The high-level plan:

From the E30 - Chassis: 1991 325i sedan - 225K miles

• Stock wiring harness, for the connector
• Stock late model radiator and expansion tank
• Getrag 260 from same, with White325is brace
• 3.73 LSD (already installed)
• Stock Booster (will relocate to clear manifold)

Not from the E30

• S50b30 - US
• 413 DME
• Vanos M50 harness
• e34 pan and tube and dipstick etc
• S52 exhaust manifolds, welded ports

Motor has 120K, but known maintenance history for the last 30K miles. It was tracked, and didn't have an oil pan baffle, so I plan to change the rod bearings and bolts, since I have to have the pan off anyhow. I am going to leave the rest of the motor as is, and slam it in.

Phase one begins today:

I need to put all the accessories on, clean 'er up, and get the bearings checked and measured and ordered up.

I'll keep the thread updated over time as I get things done, to help keep me motivated, and to maybe be a reference for others down the line.

The car, as it sits now:







Process pics to follow

[hwy84]

Well Underway!

Finally made some significant progress.

Spent the last weeks pulling together all the parts needed to take the S50 from naked long block to fully functioning motor. Oh, and cleaning parts. A lot.

Since the motor had been in a tracked car, and had 120K miles, I figured I'd go at the rod bearings. Typically the first place to lose lubrication when oil pressure drops, and an pretty easy project when the engine is out of the car.

10 of 12 bearing shells were damn near perfect, and I thought I had wasted my time replacing them... until I pulled the shells on cylinder 3. Looks like the top shell wore through the coating and well into the material beneath - as seen as the bronze color at the top of the shell on the right. Doesn't look like much, but made me happy I replaced the bearings.



Got the motor buttoned up with the e34 pan, and am now in the process of plugging on all the accessories, hoses, and related business to make this log block into a fully functioning motor.

(better pics to follow)



In the meantime, I got busy with the chassis.

Pulled the M20 and trans today - nothing new here other than the pain in the ass bracket that braces the motor against the subframe - presumably to keep it form sliding forward if the mounts tear - was just tall enough to keep the hoist from working nicely. Put the motor back down, removed the offending bracket, and it came out SUPER easy. Hooray for load levelers - I can't imagine trying this without one.

"The workshop"


Shadetree Mechanic - needed more shade


Just a little leveling, and it was out!


I can see the ground!


More as it comes!

[hwy84]

Reserved2

More Reservation

[Boris]

Building an 85 M3 4 door

Doing a similar swap on my 85 325e 4 door
picked up a 97' s52 with Trans last year.
Look forward to following your thread.

[DREWHALL]

Looks like it will end well. Good luck!

[AndrewK]

Nice! I just (mostly) finished a similar looking build. Red '89 four door with S52. I love it, especially the fact it's a plain old looking four door! Good luck!

[drumad]

^blacksburg!? man I miss it there

BTW, looking good. 4dr > 2dr definitely

[hwy84]

Nice! I just (mostly) finished a similar looking build. Red '89 four door with S52. I love it, especially the fact it's a plain old looking four door! Good luck!

Thanks, and congrats on competing your swap!

I am looking forward to enjoying the "Stealth" factor on this...

[hwy84]

...And the questions begin

Tune Question:

I came across a free Turner (Conforti) chip tuned for a 3.5" MAF only, and extended rev limiter.

I don't have a 3.5" MAF - I have a stock MAF.

My Q: For a given volume of measured air, will the voltage from the stock MAF be different from that of a 3.5" MAF?

I know a 3.5" MAF could theoretically flow more air, but I am hoping that the stock and 3.5" MAF will output the same voltage from idle up through the volumetric limit of the smaller MAF.

If that the case, I assume I could use the chip with the stock MAF, and it basically would be like running a stock tune...

Wishful thinking?

[cormier]

Why don't you just run the 3.5?

Swap lookin great man mines in progress too! Love the red ps

[Mr.SWISS]

If you are tuned for 3.5 MAF. you have to run 3.5" MAF sry.

[hwy84]

Thanks for the replies!

Been out a while, but thanks for the replies about the MAF. Gotta get the right chip. (or a 3.5" MAF). Damn.

Lots of progress though: Engine and 260 are in the car, mounted, and driveline is all connected.

PROPS: To White325is His 260 trans bracket was PERFECT in every way. I used the early 320i mounts (p/n: 23-71-1-109-173) and everything bolted up like stock. The bolts on the mounts JUST fit through the slots in the bracket (I screwed the mount through the bracket) - but they do fit. And it's awesome.

Next issue: (Yes, I searched, but didn't find the specifics...)

I moved my STOCK e30 325i booster. Exactly .5" to the driver side. Clevis was dead easy to put onto the pedal arm, but installing the pin was a PITA.

QUESTION TO THOSE RUNNING THIS BOOSTER SETUP: With the booster shaft now at a slight angle - have you run into any binding issues with the booster?

I know there is a fair amount of play in the mechanism to allow for the change of angle as you depress the pedal, and so far it feels smooth, but I want to make sure I haven't set my self up for something... unexpected.

Pics to come.

Next up - stock S52 Manifolds to Stock S50 center section. I think it's time for the BFH...

[scottinAZ]

I moved my STOCK e30 325i booster. Exactly .5" to the driver side. Clevis was dead easy to put onto the pedal arm, but installing the pin was a PITA.

QUESTION TO THOSE RUNNING THIS BOOSTER SETUP: With the booster shaft now at a slight angle - have you run into any binding issues with the booster?

I know there is a fair amount of play in the mechanism to allow for the change of angle as you depress the pedal, and so far it feels smooth, but I want to make sure I haven't set my self up for something... unexpected.

Pics to come.

Nope, no binding or other issues with a relocated stock booster. feels just like it did before the swap.

[hwy84]

Well, damn.

So I got the correct chip (found a used Dinan chip for a stock S50) and got the engine in and wired.

Sadly, I have a "cranks but won't start" situation now. I tried last night, and my battery was very weak. Thought it might catch - it didn't. I have charged the battery now, but no change in behavior. Here's the deal:

• When I turn the key to "on" I hear humming, I get the dash lights (including CEL).
  
• Stomp test works, and gives me 1281 - which is DME memory. Typically caused by low voltage... but I have good voltage now - reads 12.03 volts at the distribution block.
  
• DME is grounded.
  
• I swapped in a second ECU, with a second chip - no change, same 1281.

I am fairly certain I am not getting fuel, even after I jump the FPR. I can't hear the fuel pump whine, and I smell no fuel. Fuel pump is new - was replaced and running shortly before I started the swap.

If it helps - when cranking, the engine has a distinct cranking pattern, not just a steady rhythm of "turn, turn, turn, turn, turn" but more of a syncopated, "turn turn, pause, turn, turn, turn, pause" that repeats. Maybe typical, maybe weird.

I am an electrical newb, but I studied the hell out of the ETM to get my harness right... my swap chart is below.

I am going to check the Cam/Crank position sensors to make sure I didn't get them backwards, but I am 99% certain that is not the case.

Also, the harness grounds (2) are grounded, motor is grounded to the chassis on driver's side mount arm, coils are grounded to valve cover.

Harness power (1) is connected to dist block, as is chassis power from the battery (2 - big and small) and from the driver's side firewall (2 medium and small).


Function 1991 325i C101 12/93 E34 X20
alternator 1 25
oil level sensor (static) 2 1
coolant temp sender 4 12
oil pressure switch 5 23
power distribution box to O2 relay 6 22
ignition switch 7 21
fuel economy gauge 8 24
engine speed output 9 20
oil level sensor (dynamic) 10 2
SI RESET 11 19
check engine light 12 8
fuel pump 13 13
speed signal input 14 14
starter (unloader relay) 15 15
Diagnostic 16 17
starter (power during start) 18 18
ABS 20 3

I have to run to work, but any thoughts are welcome. Thanks all.

[Adrian_Visser]

Sorry you say you jumped the FPR?

FPR is an accepted acronym for fuel pressure regulator But I'm going to assume you meant fuel pump relay.

Jumping it, assuming you jumped the correct terminals (30 and 87) on the relay should make the fuel pump run. Obviously this is done with the ignition key in the Run position.

If not check the fuse and then check for power at the fuel pump.

Oh and congrats on the four door, I'm going to be swapping my s52 drivetrain into a '91 Delphin 318i four door in the spring as well.