E46 M52b25 Block + E36 M52b28 Head: Will it work?

[E turd]

History: I bought a decent M52b28 single Vanos motor from a 97 328i, but while it was on the stand in my backyard, the tarp covering it was blown off partially during a storm exposing the exhaust ports. The result was that two of the cylinders got rain water into them, and after sitting for several months a significant amount of rust has deposited on the cylinder walls. I tried to remove it with some pb blaster and some nylon brushes, but it looks like the cylinders will need a good hone. This full teardown of the block puts a real wrench both timewise and financially into my swap progress. My M20 crapped its pants in November of last year and I have been without a car since, desperately looking forward to the day my swap is completed.


Enter the possibility of getting another block to serve while I rebuild the one I have (from the 328i). I am looking at getting a motor from a 99 323i. From what I can gather it comes with dual vanos, a shorter stroke and an aluminum block with steel cylinder sleeves. I know it's not as powerful as the b28, but I was thinking I could run the b25 block with my fresh b28 head and then either rebuild my b28 block or transfer my b28 crank, etc to make the equivalent of the 2.8L Z3 motor.


What is the concensus on compatibility and cost? Worth it or should I just put that money into the b28 block rebuild cost?


Thanks for the help in advance!

Logan

[hoveringuy]

Not compatible. The M52tu block has completely different coolant passages than your head. Just won't fit.

[E turd]

Not compatible. The M52tu block has completely different coolant passages than your head. Just won't fit.

Exactly what I needed to know. Thank you!