My research: E34 M50B25 swap thread

[stig]

Hi all,Thought I'd share my research I did for a friend of mine wanting to swap an m50b25 into his m50b20 manual. His main concern is major engine electricals because he's not getting a half cut.For baselining, I used Jan 1991 cars to see what's different. Let's hope RealOEM data is reliable.E34: 01/1991 Manual M50B20 vs 01/1991 Auto M50B2512 05 IGNITION SYSTEMBoth part(s) numbers are the same12 10 CONTROL UNITBoth part numbers are different indicating different ECUs so a new ECU is needed. However in certain years, they use the same ECUs.12 22 ALTERNATOR, INDIVIDUAL PARTSBoth part(s) numbers are the same12 25 STARTERBoth part(s) numbers are the same12 28 ENGINE WIRING HARNESS12511703907125117039081 number different, but I guess you can retain either wiring harness...12 29 BATTERY CABLEMost part numbers are the same except 1-2 parts12 95 ACCESSORIES AND FITTINGS (MULTIPLE START INTERRUPTION)Both part(s) numbers are the same. Is this the immobiliser?SummaryIt looks like it's almost a direct swap! Do let me know if I have erred on the above

 

[julianpang]

How about fuel injectors? Are they the same?

 

[pussy]

i presume the current engine and the new one is non-vanos ?

 

[pussy]

How about fuel injectors? Are they the same?

yes, so is the throttle body, fuel regulater, intake manifold, MAF and Intake bellow plus the intake filter housing. inclusive of the exhaust manifold plus the rear pipes all the way to the rear box.

plus all this small costs, it would be more expensive than buying a half-cut.

 

[erica34]

direct swap iirc. i went from 2.0 non vanos to 2.5 non-vanos and finally vanos. in hindsight, should've listened to Al and puss and save myself quite a bit by getting a 2.5 vanos half cut which i eventually did and just skipping the 2.5 non-vanos step.

 

[anakin]

But now nice halfcut hard to find...

 

[ramsing]

i know of someone who has a low mileage e34 2.5 vanos halfcut. looks to be in v good condition.

if you're upgrading, upgrade to vanos straight. u will love the difference.

 

[anakin]

i know of someone who has a low mileage e34 2.5 vanos halfcut. looks to be in v good condition.

if you're upgrading, upgrade to vanos straight. u will love the difference.

Sing, kat mana tu...?