where does the 2.7 engine come from?

[Kieran_n22]

Someone told me some 325i have this 2.7 engine in from standard you only look the side of the engine to see what it is. And I've seen 2.7 on Alpina models. How and where does it come from because it seems to be rare too.

[m_jermyn]

The 2.7 is standard in the 525e....

This motor forms the basis of most of the 2.7 built engines you see here on e30zone. The key ingredient is the crank shaft.

Have a look here: http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.7

Basically a very torquey engine that pulls from 1500 rpms all the way through to 6500rpms with more HP then a 325i.. Torque + HP = alot of fun and a real nice ebgine.

[Kieran_n22]

Thanks a lot mate. This looks like something I'd like to do. 2 more things, how much power does it actually have and how is it on petrol compared to the 2.5?

[m_jermyn]

here you go...


So after 2 engine rebuilds and almost 1500kms on the new engine I took it for a long drive.

Armed with the sat nav to measure the distance

I travelled 252kms with 19ltrs of petrol.

I filled the tank right up double clicked the bowser, did the drive and on the way back stopped at the same servo at exact same bowser and double clicked again. So the e30 was on the same lean meaning the same amount of fuel would go in..


Very scientific arnt I?


So courtesy of a online consumption calculator as im too thick to figure it out myself..

Litres per 100 Kilometres:....7.5
Kilometres per Litre:..............13.26
Miles Per Gallon (Imperial):.37.46
Miles Per Gallon (U.S.):.........31.20


How incredible is that? And to think there was some parts where I was showing off, for the most part I drove pretty carefully and easy on easy off but im male and there is the times where I couldnt help sick my right foot into the carpet..


Pretty happy with all that.



To let you know of my mods...

Eta bottom end
731 head
Big bore throttle body
Stainless exhaust manifold
Stainless strait through exhaust
Light weight flywheel
Compression raised
Dynamically balanced crank, rods, pistons, flywheel, clutch and pressure plate
323i cam
Chipped by Atech


It pulls from 1500 rpms easily and really pulls from 3000 all the way to the limiter. Easily outruns a standard 325i as the extra torque down low helps get it going right from the start.

Hope that helps mate.

Mike

[daimlerman]

No right way or wrong way to build a 2.7,just the way that suits what sort of engine that you want.

Alpina/Hartge,Racing Dynamics/Les Stannard etc mostly used the crank from the 324d as it's virtually indestructable,also virtually un-obtainable in the UK!
With 320 'rods and custom pistons to suit the 325i(885 casting)head.

Most 2.7's built today follow Mike's bottom end spec,E28 525e short motor with either 320i(731 casting) or the 325i head mentioned above.Worth mentioning that the eta pistons do not suit the 325 head perfectly,and that 325 pistons do not come quite to the top of the bore,meaning that the block top requires 'decking' to reduce it's height slightly.

So one way is a cheap(ish) way,one way is more expensive in machining costs.

More detail is available in the wiki,BTW,follow the link button at the top of the page.

[Kieran_n22]

Aw thanks a lot guys. It's a good thing I still have my 2.0 then as I may need some bits from it. I should of thought about doing this before I put the 2.5 in! I'm gonna go home wrap my head around this and probably do it September time I'll probably be in touch again lol.
Cheers

[daimlerman]

Worth looking at is the 2.8 M20,using one of the cranks(not sure which )from M52's,gives a slightly easier build,hunt up suitable build threads and have a read,'stonesie' and 'goosiegander' are two that come to mind.

E28 eta cranks are getting a bit like rocking horse shite,and the slightly longer stroke is an added bonus.

[Cloud]

The one I have in mind for mine is the crank from the M54B30 - it's the longest stroke you can reasonably easily fit into the block. You need the bottom end from a 2.7 (525e) because it's got more crank clearance, and you also need to hack off the bottom of the piston skirts, otherwise they'll hit the crank just before BDC.

It's a bit more work, and a heck of a lot more dinero, but look at the benefits of the 2.7 over the 2.5, mentioned above, which is only a 200cc increase. The M54 crank would give you two and a half times that, 500cc, making it just a touch under (for legal reasons) a 3.0l.

[mrLEE30]

M50 B28 crank - cheap and easy to find
M20b20 con rods - cheap and easy to find
Everything else m20b25.
Only "hard" bit is the oil spacer that you need to make.

This makes 2.8 litre

No need to skim, no need to mess with the timing belt.

But to release power you also need a decent exhaust system, perhaps better injectors and a remap.

About 1-2grand should see you with 200-220hp.

[m_jermyn]

To be honest I have issues with the 2.8 M20s and anything higher although good in theory they have some issues...

The long skirt on a piston serves a purpose to keep the piston square and upright as much as possible in the bore, its to stop the bore from going oval on the thrust side. The long skirts help minimize piston rock which is what courses this.

So going to 2.8 you get the displacement but you will also get a shorter engine life... For what? very small tiny increase maybe a few hp.

Now imagine how short the piston skirts would be on a M20 with a m54 crank?


Of course its just my opinion and im no mechanical engineer but im pretty sure im right

[CHR1S1990]

325 pistons do not come quite to the top of the bore,meaning that the block top requires 'decking' to reduce it's height slightly.

according to the wiki..

To get around this, you need to use 130mm Eta/2 litre rods. Then the pistons don't come to the top of the bore - about 2mm short in fact.

Would this not work at all or would it just give a massively reduced compression? Im thinking turbo/supercharger here

[daimlerman]

325 pistons do not come quite to the top of the bore,meaning that the block top requires 'decking' to reduce it's height slightly.

according to the wiki..

To get around this, you need to use 130mm Eta/2 litre rods. Then the pistons don't come to the top of the bore - about 2mm short in fact.

Would this not work at all or would it just give a massively reduced compression? Im thinking turbo/supercharger here

Exactly!

You need to 'dummy build' one cylinder with your chosen parts to see just how much needs skimming off...


Loads of work,but your time is free....

And who claimed that tuning engines is 'cheap'?

[CHR1S1990]

if my calculations are correct (which they probably arent) based on the values in the wiki:

ETA block + 81mm ETA crank + Pre-facelift 84mm 9.75:1 CR 325i Pistons + 885 head + ~2mm off the block = 10.4:1 CR
Dont skim the block and this would be 8.6:1 CR

ETA block + 81mm ETA crank + Facelift 84mm 8.8:1 CR 325i Pistons + 885 head + ~2mm off the block = 9.4:1 CR

Dont skim the block and this would be 8.0 CR..

perfect for FI? or is there something ive not taken into account

[m_jermyn]

Spot on Go a thicker head gasket and get more boost

[CHR1S1990]

sorry if im taking over the thread!

this is interesting...
I pulled a pre-facelift (high comp) 2.5 out of my scrap car and bought an m52b28 crank to stroke it. Upon stripping the block, I found it was scored quite a bit and the pistons were quite worn on the thrust side. Annoying as I wanted to build a nice high comp engine and run it off my LPG daily.

I then sourced a cheap early (11:1CR) ETA block and was going to bolt on the 885 i had off the scrapper - compromise between CR and valve size.

Ive always had turbo in the back of my mind, but since buying a BTB3 exhaust, my mind is set on supercharging the m20.

Ive got all the bearings, rings etc in my garage and the ETA block/gubbins all cleaned up ready to go together - this would make probably about 180-200bhp maybe a little more with the BTB, and a CR of around 10:1 - too high for big boost on the SC.

If i can find some decent enough later 2.5 pistons to make the 8:0CR, and the rings I have bought (originally for the ETA pistons) will fit, i will go this route instead and run it in...adding the supercharger down the line.

What do you guys think?

[bss325i]

To be honest I have issues with the 2.8 M20s and anything higher although good in theory they have some issues...

The long skirt on a piston serves a purpose to keep the piston square and upright as much as possible in the bore, its to stop the bore from going oval on the thrust side. The long skirts help minimize piston rock which is what courses this.

So going to 2.8 you get the displacement but you will also get a shorter engine life... For what? very small tiny increase maybe a few hp.

Now imagine how short the piston skirts would be on a M20 with a m54 crank?


Of course its just my opinion and im no mechanical engineer but im pretty sure im right

You do not have to shorten the skirt on 8.8:1 M20B25 pistons when used with an M52B28 crank and 130mm rods AFAIK.

Despite all what has been said in this thread, my recipe for a potent M20 is going to be,

TD forged crank
135mm H section rods
Custom pistons 11.0:1 comp ratio
Worked 885 head
Cam undecided
Steel rockers
BTB manifold

Watch this space.

[Dezzy]

To be honest I have issues with the 2.8 M20s and anything higher although good in theory they have some issues...

The long skirt on a piston serves a purpose to keep the piston square and upright as much as possible in the bore, its to stop the bore from going oval on the thrust side. The long skirts help minimize piston rock which is what courses this.

So going to 2.8 you get the displacement but you will also get a shorter engine life... For what? very small tiny increase maybe a few hp.

Now imagine how short the piston skirts would be on a M20 with a m54 crank?


Of course its just my opinion and im no mechanical engineer but im pretty sure im right

You do not have to shorten the skirt on 8.8:1 M20B25 pistons when used with an M52B28 crank and 130mm rods AFAIK.

Despite all what has been said in this thread, my recipe for a potent M20 is going to be,

TD forged crank
135mm H section rods
Custom pistons 11.0:1 comp ratio
Worked 885 head
Cam undecided
Steel rockers
BTB manifold

Watch this space.

Interesting

[pony]

The 2.7 is standard in the 525e....

This motor forms the basis of most of the 2.7 built engines you see here on e30zone. The key ingredient is the crank shaft.

Have a look here: http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.7

Basically a very torquey engine that pulls from 1500 rpms all the way through to 6500rpms with more HP then a 325i.. Torque + HP = alot of fun and a real nice ebgine.

on the hyperlink it says:
"The 2.7 ETA ENGINE

These arrived in 1983 to power the 525e and 325e (not UK) although the US had them in 1982 for the 528e.

Eta is the Greek symbol for efficiency and it is a low revving engine rich in low speed torque but low on power. It does not rev much past 4500 and uses an 84mm bore and an 81mm stroke crank to give 2693cc. The crank is made from spheroidal grey cast iron and the connecting rods are the same 130mm end-to-end items as the 320, 320i, 520, 520i and 323i
"

When fitting this crank (from the 325e/525e engines) to a M20 engine
or
a M52TUB28 crank to a M20 does the cylinder block between BDC and TDC need to be longer to make into a 2.8 litre as otherwise would it not be just a 2.5 litre?

[CHR1S1990]

yes, the cranks increase the stroke (by 6mm on ETA/TD crank, 9mm on m52) so yes the piston moves up and down further to increase the stroke and therefore capacity - youl notice when you strip an engine the marks at the top and bottom of the bore where the rings travel to at BDC and TDC. The bore needs to be honed to clean this up for fresh rings, and maybe reamed if there is a noticable lip at the top.

[pony]

would a crank from a M54 330Ci fit straight in?
has anyone done it?
presume it would a M20B25 with a M54 330 crank would not produce anywhere near as much power as the M54B30 231bhp?

So to make a 2.5 a 2.8 you cant just put in a crank and off you go there is alot more involved I take it? Sorry I am new to all the mechanicals of engines.

[eta]

I have calculated the sideloading forces for a 2.8 compared to a 2.7. The side wall loading forces are 6% higher in the 2.8. Whether this is enough to shorten engine life by a measurable ammount I don't know. I suspect engine life on a 2.8 will vary alot depending on how well it is maintained rather than sidewall loading.

For an M20B30 using 130mm conrods the side wall loading force are only 17.6% greater than an M20B27. That I am sure is not ideal.

[DanThe]

Longer rods is where its at, investing in custom pistons is always a good idea when building a special engine

[pony]

I reckon when someone gets round to doing a M54B30 engine transplant on a E30 that is going to be one hell of a car except the S54 ones of course.

[Dezzy]

I reckon when someone gets round to doing a M54B30 engine transplant on a E30 that is going to be one hell of a car except the S54 ones of course.

M54 heads are gash.

M52B30 is where its at

[DanThe]

I have an M52B30 in my track car, close as it gets, M54 donk is a waste of good metal

[pony]

what makes the M54 cylinder head so bad?
I thought the M54 was just a straight evolution of the M52TUB engines?

[Dezzy]

what makes the M54 cylinder head so bad?
I thought the M54 was just a straight evolution of the M52TUB engines?

One word.....Emissions

Danthe has spent alot of work on one to try and make one worth using.

Not worth it imo

[DanThe]

It evolved into a more eco friendly engine than a more performance engine. Most of the engine is de-tuned for emissions purposes, the only reason it gets away with it is because of the 20 odd degree extra vanos advance to bring the power/torque back up

[Simon13]

Longer rods is where its at, investing in custom pistons is always a good idea when building a special engine

rod angle is where its at. Long rods and big bore good combo. S14 2.0 is a good example of this

[pony]

I have an M52B30 in my track car, close as it gets, M54 donk is a waste of good metal

have you had your engine on the dyno yet? how many bhp do you think it has?

[DanThe]

http://www.e30zone.net/modules.php?name ... ght=m52b30

[pony]

http://www.e30zone.net/modules.php?name ... ght=m52b30

Nice.
You taken on any E46 330Ci's in that or anything interesting or any E92s?
Bet they must be real suprised.
Did you bother with the DSC?
Is it really hard to drive in the wet?
What made you choose a M52B30 for a track car instead of a S50B30 or S54B32?

[Dezzy]

http://www.e30zone.net/modules.php?name ... ght=m52b30

Nice.
You taken on any E46 330Ci's in that or anything interesting or any E92s?
Bet they must be real suprised.
Did you bother with the DSC?
Is it really hard to drive in the wet?
What made you choose a M52B30 for a track car instead of a S50B30 or S54B32?

Cost if i know Dan

[DanThe]

Its an alloy block and weighs less than an M20
Most E46 M3's are passed with ease around Oulton

I want to get the car down the 1/4 mile as its shite off a stick especially with the gearing

[pony]

Crikey.........I bet you have a good old chuckle each time a E46 M3/996 Carrera/Jaguar XKR/Maserati Grandsporte 2006 pulls alongside you or a 335i?