m20b20 vs m20b25

[spankerdan]

hey guys,

currently i own an 88' 320i with no engines mods expect exhaust... i am really happy with the car itself i just wish it had more go...

without copius amounts of money to spend and the fact of bmw parts in australia i was considering an m20b25 swap, keeping my current exhaust and chip (though i have read that most of the chips o the market are not worth the money).

getting to the point, will this swap be worth the money i fork out?

does anyone on here own both a 320i and a 325i?

[mikeedler]

I have swapped quite a few 320i cars to 2.5l It is the best thing you can do for the car. it is an additional 40hp. It is so straight foreward it is sick. the computer/airbox is the same, as well as the exhaust if it is a plastic bumpered car. No other mods are going to bring you 40 hp for that money. and if you do any mods to the 2.0 in the end, you will just wish you had done them to a 2.5
to me the 2.0 is the worst motor around!

[Borat]

yip, you wont regret it. I've driven both and the difference is huge.

[ADEN]

should i just replace the bottom end and leave the head or replace both?are the fuel consumption is a big difference?

[SpecM]

should i just replace the bottom end and leave the head or replace both?are the fuel consumption is a big difference?

replace both, the b25i had a #885 head that breathed a lot better (vs. the #731 head in the 320i/323i)

[Borat]

I don't think you'll notice any difference in fuel consumption unless you floor it everywhere, that M20B20 is really thirsty for what it is.

[Madhatter]

id swap ecu's for the 325i item rather than running the 320i's one, even if its been chipped.

[SpecM]

id swap ecu's for the 325i item rather than running the 320i's one, even if its been chipped.

Me too. Are you going to run L-Jet, Motronic 1.0, or 1.1?

[Madhatter]

we got motronic 320i's down here, he'll already be running it :)

[mikeedler]

the ECU is the exact same one for a 320i or a 325i- there is no difference whatsooever!
you need to swap the complete motor/head along with the intake. exhaust manifolds are the same.

[Madhatter]

its no different? the maps are the same, the timing curve is the same?

how do they achieve this on both motors when the difference in power output is 50hp and its a full 500cc smaller.

Might be the same part number, but I doubt the tune inside is the same, it just wouldnt function properly.

[gstuning]

the ecu number is not the same and thus not the same software.
But I can imagine the software to be VERY similar,
Doesn´t the 2.0 have a 2.5bar fpr? That can offsett as well as other injectors.
So the combo becomes the same running

[Madhatter]

yeah, but if you change injectors, the pulse width and duty cycle will still remain the same. It would be difficult to tune two different engines using the same values, especially since the 320i runs smaller injectors.

[ADEN]

so bottom, head, intake,ecu?
that's it?

[SpecM]

I would match AFM to the ECU as well, but yea that's about it