M20 types and part compatibility

M20/M30/M50/Whatever! All engine related stuff here.
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LEAN_E30
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M20 types and part compatibility

Postby LEAN_E30 » Fri Mar 06, 2009 7:48 am

All M20s have a Timing Belt. if you do not know when your belt was changed last, M20s being an Interference valve train design, you should keep it fresh.

M20's:
325i,is,ix* = m20b25
325, 325e, 325es = m20b27
320i = m20b20
323i = m20b23
(see a trend developing here?)
(* = ix block is allegedly different, tho so far no casting numbers have been provided for proof - it would not be surprising considering that the oil pump is of a different design as to accomodate the front half shaft which passes through the oil pan and the front differential which bolts to the oil pan. At minimum it is substantially claimed that some of the oil bores may be in different locations.)

M20 blocks:
Large bores (m20b25, m20b27) [84mm]
Small bores [non-USDM] (m20b20, m20b23) [80mm]

M20 heads:
200 (m20b27, m20b23)
885 (m20b25, m20b27SUPERETA)
731 (m20b23)

885 heads have a semi hemispherical design with a domed piston face
200, 731 heads have flat-tops

Cranks by stroke length in order of largest to smallest:
b27 [81mm]
b23 [76.8mm]
b25 [75mm]
b20 [66mm]

Valve clearances @TDC:



------------------------------------------
i'll edit more info into this later, i'm outta here
Last edited by LEAN_E30 on Wed Jun 24, 2009 5:39 am, edited 5 times in total.
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LEAN_E30
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Re: M20 types and part compatibility

Postby LEAN_E30 » Fri Mar 06, 2009 7:49 am

wtf, i'm still a n00b? how many posts you gotta whore before your bumped up?
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Re: M20 types and part compatibility

Postby ten2doyle102 » Fri Mar 06, 2009 12:12 pm

I think 15 posts

Also, the IX block does has some slight differences...Perhaps you may want to noted that in the list.
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Re: M20 types and part compatibility

Postby Yoshi » Fri Mar 06, 2009 2:02 pm

Yea IX block is slightly diff. I don't remember how but I know it is.

Fix it and I sticky ;)

we are so going to fill up with stickies fast.
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Re: M20 types and part compatibility

Postby ten2doyle102 » Fri Mar 06, 2009 4:48 pm

From christ325ix on the tech

"no, the entire oil pump system is different, including the intermediate shaft. You can't bolt on a 325i oil pump onto the ix block without machine work, and you need the 325i intermediate shaft & pick up tube. The block itself is a different casting, it's not a 325i block machined slightly differently. BT, DT. :)"
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Re: M20 types and part compatibility

Postby joecrotch » Mon Mar 09, 2009 10:40 am

so the IX is a whole different casting thats crazy does anyone know the engine code for the ix then? it should be different if it is a different casting right?
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Re: M20 types and part compatibility

Postby ten2doyle102 » Mon Mar 09, 2009 3:10 pm

I have never been able to find a different cast number. I could try to check it out tonight.
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Re: M20 types and part compatibility

Postby LEAN_E30 » Tue Mar 10, 2009 5:29 am

yeah... as far as i know that's still hearsay till someone can provide proof with casting numbers, but i'll take the "ix" out of the m20b25 or make a note of the possibility
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Re: M20 types and part compatibility

Postby BlackMagic » Wed Mar 11, 2009 4:03 am

I didn't read this before my copy and paste lol
It's not a question of how fast it will go, it is a matter of how fast do you want to go.
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Re: M20 types and part compatibility

Postby LEAN_E30 » Thu Mar 12, 2009 3:15 am

BlackMagic wrote:I didn't read this before my copy and paste lol


LEAN_E30 wrote:no, no competition. my thread was just random shit off the top of my head. this looks "cut and paste".

we should just combine the two. i was just shooting for a basic table layout of main points that are easily glanced though for certain info.

i'm all on board for compiling one "M20 MASTER THREAD"

basically this data with a table layout like mine just filled in with the specs like BORE, STROKE, Rod Length, Valve sizes, and most importantly... PART COMPATIBILITY, and dyno based output specs for non-OE builds which utilize strictly OEM parts only. such as the low compression (not-yet-boosted) 885FlatTop, cam'd 885Super, or the 731b27, with different fuel management approaches, like piggy motr1.3s, markDmotr1.1, Mega, Begi, etc.etc.etc.

i like spreadsheets augmented with voluptuous charts. :mrgreen: ;) sounds nice don't it?


Copy/Paste

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Re: M20 types and part compatibility

Postby ejohnson » Thu Mar 12, 2009 7:35 pm

I and IX blocks are the same casting wise, but the machining of them was not the same. I have both of them right next to each other in my garage and they are infact the same cast. The oil dip stick tube is located in a different spot, and the oil pump machined area is different. Those are the only 2 things that I have noticed between the 2.
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Re: M20 types and part compatibility

Postby BMWIS » Fri Mar 20, 2009 2:26 pm

I would like to read more about the "Euro high compression engines"

Rated at 171hp instead of 168 as I understand it.....

This is youtube, I know....I realize everything is to be taken with a grain of salt but check this out....
http://www.youtube.com/watch?v=nq_QK4d2EXM


Who has info on the euro motor?




A couple other questions. What's the max overbore that one can do to an M20 B25. It seems people avoid overboring. Is that just to save money. I'm thinking of a .040 overbore.
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Re: M20 types and part compatibility

Postby M20_fever » Fri Mar 20, 2009 3:30 pm

BMWIS wrote:A couple other questions. What's the max overbore that one can do to an M20 B25. It seems people avoid overboring. Is that just to save money. I'm thinking of a .040 overbore.


86mm but thats pushing it.
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Re: M20 types and part compatibility

Postby BMWIS » Fri Mar 20, 2009 4:08 pm

M20_fever wrote:
BMWIS wrote:A couple other questions. What's the max overbore that one can do to an M20 B25. It seems people avoid overboring. Is that just to save money. I'm thinking of a .040 overbore.


86mm but thats pushing it.


I'm dumb. How much is 86mm over standard bore in "'s


And man oh man I was hoping someone would comment on the Euro motors.
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Re: M20 types and part compatibility

Postby M20_fever » Fri Mar 20, 2009 4:12 pm

don't know much about the Euro motors other than they have a higher CR of 11:1 which is why they are rated at higher HP, but they have much better fuel quality over there so I don't know how those motors would handle our crappy fuel.

Stock bore on a 'i' motor is 84mm.
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