Engine ID help (new guy assistance)

[slix2]

Hello all,

Backstory: I purchased a 1989 325i a few weeks ago. I have loved the style of e30's for years now, and finally had the opportunity to pick one up. The seller claimed that the original engine gave out about 25,000 miles ago and he had another one put in.

So now i'm trying to ID the engine. I don't really know much about e30's yet, but hope to quickly learn all I can! I have some experience working on BMWs - mainly working on a friends 330iZHP and now his e46 M3. But of course those are different animals in complexity!
Anyway the reason I'm doubtful that it is an "i" engine is because of the valve cover, which I've been identifying as the cover usually on ETA engines! Also, it doesn't have the T-Style ICV which I understand should be on 1989 325i's. As I've never driven an e30 before, and my usual daily driver is *a bit* faster, I cannot make my decision based on power felt by the butt-dyno.

Attached are some pictures from the top of the engine bay. I'm not sure if there are any engine codes or numbers that are stamped anywhere on the engine to identify it certainly, so I thought i'd start here with pictures:

From Passenger side:



From Driver Side:



From windshield above the brake booster:



From Passenger side, looking at front of engine:




Any help and input would be appreciated! And thank you!

[jlevie]

That looks to me to be an M20B27 engine. The valve cover, intake, and sensor in the thermostat housing are consistent with it being an M20B27.

[ZM Blue Devil]

That looks to me to be an M20B27 engine. The valve cover, intake, and sensor in the thermostat housing are consistent with it being an M20B27.

this.

whats the last 7 of the vin?

[Vin-barrett]

looks like ETA engine with I fuel injection and electricals. Would guess the 89 needed a motor at some point and was replaced with B27

[StereoInstaller1]

an ETA will choke out hard over 5K RPM, that is clearly an ETA manifold and should choke out. An M20B25 will rev willingly to 6500 and hit the limiter.

[slix2]

looks like ETA engine with I fuel injection and electricals. Would guess the 89 needed a motor at some point and was replaced with B27

This is what the previous owner told me he did about 25,000 miles ago, but he neglected to mention it was an ETA engine. I was suspicious with the valve cover mainly, but with all of your much-better-trained eyes looking at it I suppose that solidifies it.

Oh well - I will continue to drive and enjoy the car for sure - but will need to remember parts for ETA not M20B25! At least until I do a bit more learning and a swap...

And as far as having "i" fuel injection and electricals - what does that mean exactly for this engine? Is it probably running a unique tune or just ECU adapting to the sensors? Or am I misunderstanding this.

Thanks again for all of your help,
The New Guy (Aaron)

[Vin-barrett]

i guess what really matters is you dont beat it up over 5k because it likely has an I rev limiter but like the stereo fellow said it's probably not begging you to do that anyway...
drive and enjoy, dont sweat it

[IAmGary]

Coming into this thread late, it would be great to have someone (StereoInstaller1?) explain: I've got a 1989 325i and this engine looks almost exactly like mine. How can you tell it's an ETA engine by looking at it?

[Vin-barrett]

The giveaway for me was you can see where the ICV bracket was mounted on the valve cover, the plugged oriface on the intake and the unused sensors on the thermostat

[e30trooper]

its a super eta ..... You can clearly see the "i" electronics matched up with the eta intake/valvecover and TB.

[jlevie]

The first clue is the valve cover. One for an M20B25 would have a boss and two threaded holes just under the end of the intake for an intake brace. An M20B27 has that boss on the other side of the valve cover.

The next clue is the nipple where the vacuum line to the FPR connects. On an M20B25 intake that hose connects to the small object bolted to the side of the intake and that object only has one nipple. That section of an M20B25 intake is shaped differently since it doesn't have a cold start valve.

Then there is the intake itself. An M20B25 intake has much less deep valleys between the runners because it's runners are larger diameter.

The last clue I could get from the pictures is the extra sensors in the thermostat housing. An M20B25 engine only has two sensors in the housing, but an M20B27 has four.

I'll grant that someone could have grafted an M20B27 valve cover and intake onto an M20B25 and they could have recycled a thermostat housing from an M20B27. But taken all together it strongly suggests that the engine is an M20B27. Conclusive proof would be from the head casting number and whether the valve springs are single (M20B27) or dual (M20B25) and by taking a peek at the the cylinder faces with a bore scope.

[IAmGary]

Excellent info, thanks a lot!

[Bretts85E30]

If u can poke a mirror under the throttle body on the head should be the casting number between 4&5 if I'm not mistaken

[slix2]

If u can poke a mirror under the throttle body on the head should be the casting number between 4&5 if I'm not mistaken

I took a quick look around last week for a number of sorts on the engine, but to no avail. I'll try to look around there tomorrow after work for sure!

And thanks again to all for your help!

[StereoInstaller1]

I took a quick look around last week for a number of sorts on the engine, but to no avail. I'll try to look around there tomorrow after work for sure!

And thanks again to all for your help!

It is why we are all here, is it not?

Luke