2.5 or 2.7?

[Saavedro88]

Yes, this is my first post, and I'm sorry for it. I've been searching and searching, but I can't find the answer to what I need to know. I just recently acquired an 89 E30, it's in good shape, and I'm really enjoying driving it.

The problem I have is that it was advertised (on Craigslist) as having the M20B25 engine block with 885 head. I took this to mean it had the original 325i engine installed. When I went to meet the guy, he stated it was a 2.7L block from a 325e. I thought I had mis-read the ad, until I got home and verified the ad indeed, does say it has the B25 engine.

So what I need to know is how to tell for sure what engine block I have, from the outside, fully assembled. Again, I have been searching, but I haven't found anything that's useful. Thank you in advance!

[sgtskid]

http://www.r3vlimited.com/board/showthread.php?t=209580

[Saavedro88]

http://www.r3vlimited.com/board/showthread.php?t=209580

So there is literally no way to know without taking it apart? That's what I was afraid of... :(

[LateFan]

You may be able to shine a light and see with a mirror between the intake runners and/or exhaust manifold. You can see some of the castings in the head and block.

It should say 885 in the casting of the head. That would mean it's a 325i engine, OR...someone modified a 325e block with an 885 head. Here's a recent thread with some pics of the castings on the block...

http://www.r3vlimited.com/board/showthread.php?t=405749

Here's a pic of the 325e engine - you can see the plumbing on the passenger end of the intake manifold, the cylindrical idle control valve with the electrical connection, and the support bracket on the valve cover.


Here's a 325i engine - different valve cover, bracket, plumbing, and ICV in a different spot. These pics don't mean they didn't change anything, and some of these things fit on both engines, but there would be no point if it has the i head on it. An e intake on an i motor would be ridiculous.

[Saavedro88]

It definitely has all the I parts on it, such as the valve cover and intake manifold. Would those parts fit on an E head? And consequently, does the I head bolt right up to an E block? I've read something about machining pistons to make it fit. He didn't mention doing any piston work.

[LateFan]

..and intake manifold. Would those parts fit on an E head?. .

It would be pointless to put the e intake on an i head. It's much more restrictive.

The blocks are nearly identical - an 885 head bolts on. People do it to build a cheap "stroker" 2.7 engine. The pistons would have to be changed to i pistons I believe.

[e30sh]

You can see the piston top through the spark plug hole if you use a pen light. The piston tops are different enough between an ETA and i that you should be able to tell which piston you have.

Also right above the starter is the build date for the block. Uses Day / Month / year format. So 25 5 86 would be May 25th 1986. If it's dated 84-86 it couldn't be an i block.

[digger]

http://www.r3vlimited.com/board/showthread.php?t=405749

[Saavedro88]

http://www.r3vlimited.com/board/showthread.php?t=405749

Thanks for that one. There are two pictures in there and my engine block looks like this one with the bolt holes directly under the oil filter adapter:


So I definitely have a 2.5 block then, correct?

[Saavedro88]

So here is an interesting new development. I got in touch with the previous owner through a local facebook group, and he was super cool about giving me some more info. He stated he got the engine from a 1988 325e, and that he did not replace the pistons, he only replaced the rings and bearings.

Now, someone correct me if I am wrong, but 1988 was the year of the Super ETA, right? Which means it's basically just a 2.5L bottom end anyways?

[digger]

SETA is a 2.7L but it has m20b25 type pistons to suit the different head, its still low compression but better than a 885 onto ETA swap

[Saavedro88]

Good to know. So here's a video that I grabbed using my buddies absolutely terrible smart-phone borescope. Does this look like a SETA piston? I really can't tell, it looks like it might be, but I'm only comparing with photos from the internet.

[e30sh]

Really hard to see. Did you check the build date on the block?

You could always take it to a dyno. A few more hp than an i if it was built right and a noticeable amount of midrange.

[Saavedro88]

Really hard to see. Did you check the build date on the block?

You could always take it to a dyno. A few more hp than an i if it was built right and a noticeable amount of midrange.

I was planning to do this anyways, since it has an aftermarket ECU in it, and it runs terribly when it's cold right now. I kinda wanted to know what to tell him before I went though.

I didn't look at the date stamp, but I'll do that today. Thanks for everyone's help so far.

[325e '87]

My '87 eta has the word "eta" cast on the block right above/around the #5 spark plug hole. Couldn't you just look for the "eta" in the casting?