Are all 325 engines the same?

[e30ze]

Got a 1990 325i with a shot engine,are all e30 lumps the same,is there a difference between early and late types,and are they interchangeable from 5 seires etc,any help much appriciated.

[thesaint]

to my knowledge all 325 engines are m20 engines. so yes

[stevetigger]

to my knowledge all 325 engines are m20 engines. so yes

no

you have
m20
m30
m50
m54
r6

[tylerma]

for the e30 they were all M20

as far as I am aware the m30 was never 2.5
I think the smallest m30 was 2.8

[stevetigger]

as far as I am aware the m30 was never 2.5
I think the smallest m30 was 2.8

E28 had 2494cc M30

[Ziggy]

Of the m20s (all standard e30s & early e34 5series) there are 2 different types, running different versions of the motronic management system. It's possible to swap this over between engines though. The earlier type ran higher compression (it was lowered for emmisions reasons etc) so produces more power, all else being equal. An early lump, with your later management will make for a nice engine.

[Brianmoooore]

E34 M20B25 engine has a few external bits different from the E30 version, which would cause difficulties if you were upgrading from a M10/M40 to a 325, but as long as you've got an old 325 to pinch bits from, there is no problem.
525 version could possibly have lived an easier life as well.

[GDBN]

Hi Ziggy ... can you tell me what it would entail to change the electrics as you say. I have an '86 325 with I think the "early" wiring but a new head (could have changed the compression). Do the later ones have the oxygen sensor and stuff too or not ??

Giles