M50/M52 Differences

[e30strokr]

Just when I thought I had everything together for my M50 with M54 rotating mass swap...

looks like I got a M52 iron block.. I was under the impression that M52 where aluminum

I cant seem to find a reference for the stamp on the bottom of the block

BMW Block 1748933 "b" (M52)

bottom of block
36208079 (?)
25 6s 2 (2.5 ltr?)

back of the head
SB A 41031 ??

now the issue is what does the Referee station check for OBD1-2 compliance? the ECU? the block?

what parts should I order from M50/M52?? are the two blocks the same?

[323i E30]

25 6S 2 shows as M50B25: http://www.ge39.com/files/zeigeinfo.pdf
M52 would have a 3 or 4 as last digit.

[ForcedFirebird]

m52tu should be aluminum and have the same coolant passages in the front, like m54, cable TB (not DBW). M52b25, b28 are iron blocks and backward compatible to m50, but not forward since the OBD system used a rear-mounted crank sensor with a reluctor ring bolted to the crankshaft (as well as missing the additional front cooling passage). M50/s50us used a front crank trigger and pre-OBD (OBDl), and used the same cooling passage system as the m20.

[moatilliatta]

Euro and 97 Z3 "E36" early "E39" Non Tu motors were aluminum block.

[e30strokr]

25 6S 2 shows as M50B25: http://www.ge39.com/files/zeigeinfo.pdf
M52 would have a 3 or 4 as last digit.

you just made my day!!! now I can go into this swap fully committed

thanks much for the help!!!!! Ill save that document for reference at the smog if necessary

[323i E30]

:) Good luck!!