How to tell if an engine is 2.5i or 2.7i

[herbie]

Hi R3v,

So the E30 I bought is an 84 318i with an M20 swap. The Previous owner said the engine and transmission came from an 87 325i which he as no proof of. All this time, I assumed the engine is an M20b25. When doing my shifter, I googled the VIN on the transmission and donor car turned out to be an 87 325e.

Is there a way to tell, without opening the engine, if this is a 2.7i or a 2.5i?

The block stamp is 2.5. on the side, the numbers say 26096291. The ECU it is running on is Bosch 380 with a Turner Chip, if that helps.

Just trying to learn more about my Frankenstein of a car. It pulls really hard so I am happy either way, but I am very curious more than anything.

thanks in advance.

[digger]

What is the head casting number? The last 3 digits on intake side of head should be 885, 200 or 731.

[herbie]

What is the head casting number? The last 3 digits on intake side of head should be 885, 200 or 731.

Hi, I’m pretty sure it is 885 because while i haven't removed the manifold to check, i peeked through and saw 1 705 on the casting. But it’s possible they changed the head and retained the bottom crank set up.

[digger]

If it's an 885 it doesn't tell you anything. If it was a 200 it would tell you do something

[herbie]

If it's an 885 it doesn't tell you anything. If it was a 200 it would tell you do something

Yeah, that's what I figured too and thought someone here would know if there's a way to tell.

The reason I think it is a 2.5i and not a 2.7i setup is that he was building it to be legal for Spec E30 racing, but then again, if there's no way to tell, what's stopping him from keeping it as 2.7i, if it is.

Thanks for the response.

[Jaxx_]

there is a way to do it--they do it for verifying engines in competition without pulling them apart. I assume it is some function of rotating the crank and measuring the air in/out.

[herbie]

would it be possible to use an inspection camera through the spark plug holes to see the pistons if they are flat or domed? Sorry for the noob question. Not sure if that would tell me anything.

Come to think of it, I guess it's not that important whether it is a 2.5i or a 2.7i.

[digger]

Yes you should be able to see

[herbie]

I'm stumped. these are the best pics I could get and can't tell what type it is. Maybe you guys can help.

https://ibb.co/wLrD8sk

https://ibb.co/NTxG27T

thanks

[2mAn]

Was this a cosmoblau sedan from Escondido area?

The pic is a bit hard to tell exactly what Im seeing, but that may be a M20B25 style piston with the notches for the valves. The eta bottom end is a simple dome, the 325 is a bit more complex

The cylinder head should be easy to spot the number. 2.7 vs 2.5 isnt much difference though

[herbie]

Was this a cosmoblau sedan from Escondido area?

The pic is a bit hard to tell exactly what Im seeing, but that may be a M20B25 style piston with the notches for the valves. The eta bottom end is a simple dome, the 325 is a bit more complex

The cylinder head should be easy to spot the number. 2.7 vs 2.5 isnt much difference though

Hi 2man,

Thanks for the response. I am almost convinced the engine M20b25 mated to a getrag 260 from the donor eta. This early 318i is some kind of a frankenstein, with an e46 steering rack, e36m3 shifter, and 3.73 from god knows where. No, I bought this car from a guy in LA whow was prepping it for spec e30, the car was on primer with a race number painted on the side, but the OG color is Baltic blue. The swap, as well as most of the work, was done by Castro's. I'd hate to call them just to ask since that would mean them having to search in their database and they probably don't have records anyway aside from what the invoice says which doesn't say much. A lot could have been don to the donor car too which they would know nothing about.

Do you think it will be too much of a hassle to get this car BAR and smog legal? It still has the carbon canister, a 325i catalytic converter, and the stock airbox. When JMP checked for vacuum leaks, it doesn't have any. I just need to wire a CEL since it doesn't have one (as read from your other post and other threads).

Since you have experience, is the CEL as easy as looking for the black wire that goes to the ECU and tapping a light into that and a switched hot wire? Do you think I'll have other problems with the visual? the car runs very well aside from it running a tad rich on start-up as it shoots some black carbon residue from the exhaust together with the condensation.

I'd appreciate any input.

here's a pic from his ad a year ago.

[TobyB]

A 380 ecu is for a 2.5, if that helps. You'll have a front cps, too, not 2 in the bellhousing.
It is quite easy to use an eta trans+ 325is engine combo- what about the vin stamped on the
engine block pad?

I hate to tell you this, but you are missing a kidney. Did you spend a wild night with a
Czech girl a while back? Are there chunks of your memory missing? Some stitches
that you don't remember?

I have one of those cameras, too, and it's frustrating what they CAN'T see...

Since you have a 3.73, you have a mid- case diff- the other things to check are
rear brakes (drum or disc)
and the diameter of the front strut tubes.

As to BAR, I cannot help, as I live far enough east in UKC that I don't have to smog...

t