m20b20 to m20b25

[amdr]

Hi

I just bought myself a m20b25 to put in my e30 320i.
Is this engine plug n play? Or am I going to encounter problems?
They look identical so :p

Thanks in advance

[eta]

You'll need a motronic engine managment plus looms if your car is pre facelift. If its L-jetronic system on the 320i will not work.

I'm sure its do-able.
The gearbox you have is getrag 240 and might not work with the 2.5.

http://bmwfans.info/original/E30/4-T/32 ... l-23_0293/

The above site lists the 260 gearbox fitted to 325i, working with the 320i and the 240 gearbox fitted to the 320i working with the 325i. While the part numbers may be interchangable this seems wrong and is worth checking out properly.

[amdr]

Yes i also have a gearbox of a e30 325i.
I already know I need a 325i propshaft but does that fit properly on my diff and on my 320i?

[eta]

Should do.

[Brianmoooore]

Nearly everything is different between a M20B20 engined saloon and a M20B25 engined saloon, but either engine will fit either gearbox.
Assuming both engines are either pre or post facelift, then it's plug and play.
The diffs are completely different, but again, are directly interchangeable.

[amdr]

yes my 320 is nfl and the engine comes out a nfl too. So its all gonna be plug 'n play. Sounds good

[Coyote_ar]

The diffs are completely different, but again, are directly interchangeable.

you mean ratios or housings?

[Silverfang]

The diffs are completely different, but again, are directly interchangeable.

you mean ratios or housings?

Ratios, the housings will bolt up to the same positions, it's the internals that are different.

320i usually have a 4.1 open diff (Small case) which won't last long behind a 2.5 M20 though give stonking acceleration But would give a poor MPG since it'll be doing about 4000rpm at 80mph

325i diffs come in a variaty of ratios, but as far as i know came with either 3.91 , 3.74 (RARE) or 3.64 i believe. being that 3.91 and 3.64 i think are also a Limited slip diff

[Brianmoooore]

The diffs are completely different, but again, are directly interchangeable.

you mean ratios or housings?

Both!

[e30bmlover]

my car is a 1990 320i... i have a 87(pre facelift) 325 engine in her. she is running on the 320's gearbox, prop, and final drive(4.1) and a facelift 325 ecu(because the engine is running on facelift monotronic) the only thing you have to do is change the toothed pully for the crank position sensor... if the 325 engine was a facelift... i wouldnt have changed it, it would be plug and play. i cant wait to get my 3.64 lsd on!!! all that needs to be done on that is adjusting the length of the prop.

[Coyote_ar]

i thought all 6 pot cars had the same sized diff, only changing the ratios.

my 320i runs at 130km/h (~80mph) at 3500rpm on fifth gear (0,81 is the ratio i believe). so i guess i dont have a 4.1.

im running on 185-70-14 wheels.

[Jhonno]

i think a 325i sits about 3k @80..

[jaistanley]

My 4.1 diff'd 325 sits at more like 4k at 80... I doubt a 3.91 diff'd car is much different.

Acceleration is pretty good with that ratio.