M20 2.7 and 885 head Engine identification

[edf]

Hi, I am wondering if anyone can help identify this engine I got from Facebook which was supposed to be a 325 engine.

I have attached some images.

It says 2.7 on the block which was the first sign that I may have a problem.

I think it says 27 6E A (the “2” is not really visible but I guess it can only be that).

The engine number appears to say 1095871

It also says 0138 and 5500 on the other side of the block.

The head says 1 705 885 on it.

The engine is in my brothers garage but he should be able to get an endoscope into the pistons tomorrow if that will help, but does anyone have any ideas what I have here?

[edf]

Images didn’t seem to attach

[flybynite]

So you have a 325i 885 head and 325i inlet but a 2.7 eta block. What version of motronic was it running?

The engine could be a 325e/525e engine (super eta) 2.7 with a 325i manifold

Or it could be one of the common 2.7 convesions that were done. Have a read of this to give you an idea

https://www.e30zone.net/e30wiki/index.p ... ding_a_2.7

Only ways to tell is to measure the stroke (difficult but not impossible with the head on)

Measure the con rods (it will have 130mm instead of the proper 135mm) again difficult without stripping the engine.

You could try to measure the block height to see if it has been heavily decked (again see 'building a 2.7' above)

Unfortunately only way to be sure is strip it down

[edf]

Thanks, not what I was hoping to hear! I have tried to do a bit of reading, will an endoscope image of what the pistons look like help do you think?

[edf]

I got it from someone near Spalding, they had a few things lying around (like a yellow Del Boy reliant Robin!) but I don’t think the engine has been in a car for some years - perhaps 10 or more but I forgot to ask!

[flybynite]

Thanks, not what I was hoping to hear! I have tried to do a bit of reading, will an endoscope image of what the pistons look like help do you think?

If you have an 885 head then it will likely have the 885 pistons (either HC or LC) anyway so not much help unless it has been completely cowboy built and you spot pistons for the 200 head.

It may just be a 325i that has used an eta block to replace worn bores. Most likely it is a 2.7 but unfortunately there are several ways of building one, some better than others. If it is a good running 2.7, might be a bonus?

Has it got a vernier cam pulley?

Unfortunately many of these engines have been stripped rebuilt and played with over 30 years so only way to know for sure is strip it down and measure

[edf]

Thanks for all the advice, my brother just took the cam cover off and this is what it looks like -it just looks standard, does that mean the “cowboy” build is looking likely?!

[flybynite]

You have a proper sintered pulley so it is looking like a later engine or somone has taken the time to swap it from the unreliable pressed ones. Most 2.7 builds would need a veriner pulley to run at all.

What I would call a cowboy build would be one that left the eta pistons in. 200 head pistons do not have individual valve reliefs

You may have a super-eta which had the 885 head so would not need a vernier pulley. The intake is not correct for that though.

You could try to measure the stroke with a bent piece of stiff wire through the plug hole from BTC to TDC that would tell you what crank you have.

2.7 super-eta is not a bad engine, lower power but higher torque and uses 130mm rods, but not really as good as the higher revving " i " engine which has the 135mm rods.

As i say, mostly guess work until it is taken apart unfortunately.

[edf]

Ok, well perhaps this might be some good news.

However my brother thinks it has standard ETA pistons from the brief look he got on his old endoscope before it broke but he won’t get the new endoscope until this eve to get a photo.

Regarding the stroke measurements, he will try and measure to see what it is, what are the different measurements it could be?

On the link you sent it says 81mm - does that mean if it is 81mm we just have a standard eta bottom end with standard ETA pistons?

Also if he measures the block what measurements is he looking for and what is a reliable way of doing this?

Thanks again, I was hoping to not have to strip it but it is looking more likely I might!

[flybynite]

Have a look through the wiki here it will tell you a lot

https://www.e30zone.net/e30wiki/index.php?title=M20

If you have 81mm it only tells you what crank, pistons do not affect stroke. 81mm=2.7 75mm=2.5

Pistons you have to look at the top. Google some pics of pistons and look at the wiki page above. Some are difficult to tell apart without taking the piston out due to differing skirts. but 885 and 200 pistons are easy enough.

Accurate deck height is difficult with head and sump on but it should be 206.2mm If it has has 2mm taken off it should be obvious and the block cannot be put back to B25 i spec as it will be to low for 135mm rods.

[edf]

Right, thanks for all your help, and now I have got some sort of update after some measurements and endoscopy!

Looking at the images of the pistons, do they look like ETA or something else?

Also I am a little confused about the other stuff.

My brother measured 272mm from the bottom of the block where the sump joins to the top where the head joins which doesn’t seem to be anywhere near the figure of 206.2mm and the stroke he thinks (though he admits it was very hard to measure through the spark plug hole) is apparently about 92mm?!

Am I looking at a mega-cowboy build do you think?

Does any of this sound odd or normal as now we are totally lost!

Thanks again

[flybynite]

Well that looks to me like you have a standard 2.7 eta bottom end with an 885 i head.

The pistons look like those for the eta 200 head. This is known to run but it won't be the best way to build a 2.7.

My mistake on the deck height, I think it was the measurement for the stack height (rotating assembly) can't say I have the deck height to hand.

As it stands it probably won't have the power of a 325i or the torque of a proper 325e. Thats my guess anyway.

[DanThe]

That looks like a valve has hit the piston, they also look very much like flat top eta pistons, 92mm stroke is very unlikely

[edf]

The pistons are fine my brother says, it was some oil that dropped in.

Other than that it all seems to be sounding a bit crap!

He said it was hard to measure the stroke, is there an easier way that a bit of wire?

Would the sintered cam pulley suggest this is just an 885 head on an ETA block which it is suggested is the worst of both worlds and is that what I have do you think?

[flybynite]

That looks like a valve has hit the piston, they also look very much like flat top eta pistons, 92mm stroke is very unlikely

Yes they look like the 200 flat top pistons but i think the 2.7 eta pistons had one valve relief on them unlike the other 200 head pistons (320/323) which did not IIRC

I think if he has measured 91mm diagonallythrough the plug hole it could have been 81mm vertically but highly unlikely 75mm

Dan, can you remember anywhere that has the block height written? checked everything I have, can't remember where I saw it written.

[DanThe]

Looks like there is slightly raised material on the curve which could be from impact

Google search brings up 206mm from various sources, I dont think ive ever measured one, I always measure from the top of the piston up

[flybynite]

which it is suggested is the worst of both worlds and is that what I have do you think?

At the moment it is worst of both worlds but still a basis for a good engine, just not as it is. The way I see it is you have 2 choices without going mad.

1. get a 325i crank, 135mm rods and pistons, build it as a 325i
2. get super-eta pistons to go on your 130mm rods and make a proper 2.7 super eta.

Worst case if the block has been severely decked a second hand m20 block are fairly common.

3 You could build a proper 2.7 with that crank, 135mm rods and custom made pistons (similar to an Alpina) but pistons will be a few ££

[flybynite]

Looks like there is slightly raised material on the curve which could be from impact
Google search brings up 206mm from various sources, I dont think ive ever measured one, I always measure from the top of the piston up

I know what you mean I thought that too but I think it is more the light and poor camera.

I had 206mm but just put a tape on one I can just about reach and it is more like 270mm

Never had to use it much either as you say from the top is the important direction

[DanThe]

The measurment is from the centre of the crank upwards

[Andyboy]

There is nothing wrong with using 2.7 Eta pistons. I was doing these 20-25 years ago and they have a good compression ratio and do decent power.
There are two Eta pistons, the early one up to 9/85 with the 11:1 compression and the later one with 10:1. The 325i head has slightly bigger chambers which lowers the CR from these figures down to 10.4 and 9.4 respectively. The 325i pistons are a bit better but there's not much in it. Yours is an early high compression unit from September 1983. Should be 276KA or 276EA.

325i bottom ends aren't really worth a carrot but an Eta one certainly is. I would be examining the camshaft for markings - it might be something a bit spicy.

Valve to piston contact may be because there is no centre bolt securing the cam pulley to the cam. There should also be a three legged adaptor that the rotor arm bolts to. Those look like standard Eta valve cut outs.

[flybynite]

The measurment is from the centre of the crank upwards

Yeah that is what I have written down, I thought a total block-height measurement might be easier to measure on a built engine but can't find a measurement.

and do decent power.

I know you were doing these but I think there are some urban myths about these 2.7 engines.

I can't see how an eta with flat top pistons would do better than a super-eta with the correct ones and higher CR. The super-eta was a better than the eta but always the poor cousin to the 325i. 127bhp and 5500rpm IIRC

It will have done more torque lower down which might have impressed the bum-dyno but I remember driving some years ago when my 323i was on the road and not being impressed anything above 3000rpm. Good running 325i is still hard to beat.

IMHO only way to get decent power out of a 2.7 is the way Alpina did. 135mm rods and the correct piston for the head whether it be 885 squish or hemi.

[Andyboy]

The super-eta was a better than the eta but always the poor cousin to the 325i. 127bhp and 5500rpm IIRC

That's because it used the Eta camshaft.

[reggid]

ETA bottom end with 325i top end is rubbish and not worth the time

[steve_k]

I got it from someone near Spalding, they had a few things lying around (like a yellow Del Boy reliant Robin!) but I don’t think the engine has been in a car for some years - perhaps 10 or more but I forgot to ask!

the yellow robin sounds familiar to me, it wasn't a guy they call dirty Derek? little london near spalding?

best way to check it to get the head off & get some proper pics then we might be able to help you,

if it is a 2.7 eta then you have the basis for a stroker m20 with would give you an "as new" engine.

[reggid]

What is the goal or purpose of the engine ?

[DanThe]

As it would happen I currently have a 2.7 eta short engine on the engine stand for a refresh/upgrade, came with an 885 head too

Here are some pictures of the pistons next to a 2.5 piston, you can clearly see the huge dish in the eta piston compared to the 2.5

The 2.5 piston has had the exhaust valve relief machined deeper in a previous life so ignore that

[DanThe]

It says 2.7 on the block which was the first sign that I may have a problem.

I think it says 27 6E A (the “2” is not really visible but I guess it can only be that).

The engine number appears to say 1095871

I put the engine number into realoem, older cars have the VIN on the engine, yours is from an E28 525e

[flybynite]

I put the engine number into realoem, older cars have the VIN on the engine, yours is from an E28 525e

If the engine is 9/83 then it is not a Super-Eta and the 885 head has been put there afterwards, block has probably been decked beyond what can be used for a proper 2.7/2/9 build. Not a great loss but something to consider I guess.

[Andyboy]

ETA bottom end with 325i top end is rubbish and not worth the time

Righto.

[reggid]

ETA bottom end with 325i top end is rubbish and not worth the time

Righto.

Well it isn't, a 2.7 with 81mm crank, 130mm rod, b25 piston, 885 head and blocked decked etc is easily worth the effort over putting the 885 head onto a complete "conventional" eta bottom end, same with the 2.8 using 84 crank, b25 piston, 130mm rod it will also make more power and torque across the board as its not a random collection of mismatched parts. The piston and cylinder head must go together (match) with a sensible CR else it will not be efficient

[flybynite]

Well it isn't, a 2.7 with 81mm crank, 130mm rod, b25 piston, 885 head and blocked decked etc is easily worth the effort over putting the 885 head onto a complete "conventional" eta bottom end, same with the 2.8 using 84 crank, b25 piston, 130mm rod it will also make more power and torque across the board as its not a random collection of mismatched parts. The piston and cylinder head must go together (match) with a sensible CR else it will not be efficient

I always thought a better option was to get some standard "super-eta" pistons, for a long while they weren't that expensive new and made for the job. If it wasn't for my loathing of the 130mm rods it is something I might have done.

I remember driving a few 2.7 back in the day when I was looking for more grunt from the 2.3 and not being impressed. The 2.3 had its faults but it was happy to rev its nuts off. Most of the options I looked at might have had a bit more at the bottom but lost everything at the top.

I remember only two engines impressed me at the time, Alpina 2.7 and the early 325i

[reggid]

Well it isn't, a 2.7 with 81mm crank, 130mm rod, b25 piston, 885 head and blocked decked etc is easily worth the effort over putting the 885 head onto a complete "conventional" eta bottom end, same with the 2.8 using 84 crank, b25 piston, 130mm rod it will also make more power and torque across the board as its not a random collection of mismatched parts. The piston and cylinder head must go together (match) with a sensible CR else it will not be efficient

I always thought a better option was to get some standard "super-eta" pistons, for a long while they weren't that expensive new and made for the job. If it wasn't for my loathing of the 130mm rods it is something I might have done.

I remember driving a few 2.7 back in the day when I was looking for more grunt from the 2.3 and not being impressed. The 2.3 had its faults but it was happy to rev its nuts off. Most of the options I looked at might have had a bit more at the bottom but lost everything at the top.

I remember only two engines impressed me at the time, Alpina 2.7 and the early 325i

i personally would use the early 9.7:1 b25 slugs, 9.4:1 or 8.8:1 B25 slugs in a 2.7 recipe as a preference over the SETA as its 8.5:1 for the SETA vs 9.3 to 10.2:1 with the 8.8 and 9.7 pistons respectively

i would rather a healthy b25 over a hodgepodge eta with 885 head

[flybynite]

i personally would use the early 9.7:1 b25 slugs, 9.4:1 or 8.8:1 B25 slugs in a 2.7 recipe as a preference over the SETA as its 8.5:1 for the SETA vs 9.3 to 10.2:1 with the 8.8 and 9.7 pistons respectively

i would rather a healthy b25 over a hodgepodge eta with 885 head

That is the conclusion I came to in the early 90s. Gave up on making the 323i a 2.7, bought a nice 325i and was happy with that until my M3 came along.

But never able to get how the 2.7 Alpina drove out of my head which is why the 323i is getting a 2.7 but built the proper way. Forged crank, 135mm rods with the correct pistons for 10.2:1 and correct 885 squish. Schrick cam, BTB3 wider throttle body & the rest of the works.

[reggid]

i personally would use the early 9.7:1 b25 slugs, 9.4:1 or 8.8:1 B25 slugs in a 2.7 recipe as a preference over the SETA as its 8.5:1 for the SETA vs 9.3 to 10.2:1 with the 8.8 and 9.7 pistons respectively

i would rather a healthy b25 over a hodgepodge eta with 885 head

That is the conclusion I came to in the early 90s. Gave up on making the 323i a 2.7, bought a nice 325i and was happy with that until my M3 came along.

But never able to get how the 2.7 Alpina drove out of my head which is why the 323i is getting a 2.7 but built the proper way. Forged crank, 135mm rods with the correct pistons for 10.2:1 and correct 885 squish. Schrick cam, BTB3 wider throttle body & the rest of the works.

in the late 90s and early 200s the 323i was a blast it "came on the cam" pretty hard just so much fun.

There is a nice collection of 2.5/2.7.2.8 dyno stuff here
https://www.r3vlimited.com/board/forum/ ... yno-thread

After almost 25years of dealing with the m20 i have concluded the ideal OEM+ 2.7 bottom end build for a 885 head
- 81 stroke (cast is enough)
- 135mm rod (24V rod is lighter but m20b25 works fine)
- b25 style dish-dome piston with compression height adjusted (i.e. alpina or forged replicas in 4032 with OEM dish dome)
- setup to squish clearance 1.0m

then it comes to the head and cam combo
- 27x cam with lobe centres no more than 110
- fettled head, its really hard to find someone truly comptent though unfortunelty most shops have no actual idea. - It just takes right valve job angles, backcut intake valve , blended throats and bowls and tweaking of short side no major material removal or port size increase required

[DanThe]

Forged crank, 135mm rods with the correct pistons for 10.2:1 and correct 885 squish. Schrick cam, BTB3 wider throttle body & the rest of the works.

I wouldnt get too worked up about the diesel crank, nice to have but its heavier than the eta version