Difference between 2.0 and 2.5 M20 engines

[CGL325i]

Hi,
I'm looking for a new M20 for my 325i - a mate of a mate is breaking a car that is badged as a 320i, but he assures me the engine was replaced with a 2.5.

How do I make sure this is the truth? Is there difference I can see easily - e.g. throttle body, ECU, etc? Can I tell from the engine number?

Cheers for any help you can give,
CGL

[kidsinister]

If the numbers on the side of the cylinder head end with '731' it's a 2.0L.

The 2.5L should be '885'.

[Speedtouch]

Most immediately identifiable is the inlet manifold (that sits on top of the engine); on the 325i it has rounded curves while on the 320i it's angular, although they can be interchanged so it's no guarantee.

[jmc330i]

On the head between plugs 1 and 2 on a 2.5 there should be something like this (I think some 2.5s only have 2.5 stamped on them)......



Not sure what it says on a 2.0ltr.

[Brianmoooore]

Engine number (by the LH engine mount) . First two numbers are capacity, IIRC.

[Speedtouch]

325i block also has an 'E' (High compression, pre late '88) or 'K' for low compression (late '88 on) following the engine no.

[CGL325i]

Thanks for all the help fellas,
I went to look at the engine last night - numbers stamped on the block next to the LH mount are as follows:
20 6KA
24424533
(I presume the "20" is the number I am interested in)

I didn't take the rocker cover off to see the number on the head, but there was no number "knob" cast between plugs 1&2

Intake manifold runners were angular rather than curved.

Looks like it's a 2 litre then......

[jmc330i]

You dont have to take the rocker cover off to see any numbers - the '731' or '885' numbers are on the side of the head (inlet side I think, but could be wrong).

It does sound like a 2.0l though.