M50 vs M52 head (euro)

[raimo]

As i found out today, the heads arent exactly identical.

the M52 (single-vanos) head has
1) more coolant passages
2) one less mounting hole for detail nr5

http://www.realoem.com/bmw/showparts.do?model=HD51&mospid=47375&btnr=11_1286&hg=11&fg=25

front left bolt cannot be attached, but its ok without it too
3)valves, valve guides etc

no temp sensor differences, both have 2 tapped holes and one hole for coolant.

[DanThe]

Head gaskets are the same for both engines, so coolant passages are not a problem.
Valves are different, I think the M50 valves have larger diameter stems.

Temp sensors are different, M50 has two, one for the ECU and one for the gauge while the M52 has one twin sensor

[raimo]

the m50 is non-vanos

head gasket is the same, yes, it has more holes like the m52 has.

my m52 has two sensors holes

im going to put m50 cams, valves and valve springs to m52 head. this way i get more cooling and the m50 head is easier to sell here. i bought m50 valve guides and i gonne machine them down a bit because the outside diameter is also bigger.

[DanThe]

Ive had two heads pressure tested and refaced recently, one was from an M52 2.8, the other from an M50 N/V 2.5

The M50 had to have the valves removed for skimming as they protrude the head face. I can only assume this head will give higher compression.

I doubt the extra coolant passages will make any difference, if you want cooler running get an 80° stat