Yet another 2.7 question

[Andy_magic]

I've possibly got the chance of a 525e engine in good condition, I have a spare 2 litre engine out of the spares 320i.

Can I just pull the head off the 320 and drop it on the 525e block. If so, what compression ratio would I end up with and what sort of power.

If this were possible I would probably leave the 320 fuelling standard until I got all the right bits such as 325i TB and AFM/Manifold & Zone chip

I have done a load of searching through the forum and have read about machining block etc, this is not something I want to get into.

Cheers

[Templ8e30]

Hi Andy, yes the 2 litre head fits perfectly and has the exact same combustion chambers as the 525e head but with bigger ports.

The compression ratio will be about 10:1 depending on the year of the engine, earlier ones had higher compression than later ones.

Ideally you need a 325i inlet manifold with throttle body and blue top 325i injectors and 3.0 bar fuel pressure regulator along with a 325i Airflow meter and 325i camshaft. your standard ecu fitted with either a 325i chip or a zone 2.7 chip will really make it sing.

I modified my 525e head heavily by enlarging the ports to 325i spec then polishing them, I also drilled oil feed holes for the extra 3 camshaft bearings that the eta head does not use. I also had the new valves ground with 3 angle race style seats to give even more flow.

I also fitted a standard 325i cam although this will be replaced with a schrick 272 at a later date.

My friend has a honda prelude vtec (200bhp) and my 2.7 is faster and has more torque than his. Its a monster.

I'd advise fitting new piston rings and main/big end bearings while you have it in bits, and a new oil pump is a good idea too Ԛ£50 from GSF.

The 2 litre gearbox is ok but the standard small case diff's can be a bit weak, get a 3.64 large case from a chrome bumper 325i and you'll be doing 3200rpm @80mph in top

The 2.7 is a nice torquey but still revvy engine.

Cheers,

Iain T

[Jimbob]

if you were to keep the fuelling standard for a few days/weeks then you'll need to get a standard 325i chip

[Widge]

Hi guys,
Is it possible to use the 2.5 head? and would it give better compression?
Also what is the differences between the 2.0 and 2.5 head?
Cheers just reckoning things up before I take the plunge.
Sorry for hijacking the thread andy

[Jimbob]

I am using the 325i head bud.

[Andy_magic]

Hi Ian,

Thank you for an excellent reply, I saw one or two of your posts when I did my search earlier. This one however answered all the question I could think of and covered a few extras (325i cam)

I understand the cat equiped 525e had 9:1 and the earlier ones will be higher at 10:1. I'm pretty sure the car I'm in line for is an 86' so will be the higher of the two.

I would do the shell bearings/rings/pump as a matter of course. I don't think I'd go down the porting route (yet) as this is very labour intensive, plus I don't have the patience required to do a proper job.

Any Ideas what a 325 gearbox would be like on the 3.64 diff, I'm guessing the normal pattern getrags are overdriven on 5th gear, is there a difference between 320 & 325 5th gear ratios.

After thinking about it, I would do the fuelling at the same time so no worries there. It's no real extra work involded apart from changing the injectors/fuel rail and ECU.

I will have plenty of time to prepare for the 'implant'

Any recommendations on the make of head gasket etc anyone?

Now this is a silly question, but what sort of MPG do you get - lol

[Jimbob]

...

[Andy_magic]

Sorry for hijacking the thread andy

no worries, you can share risk of asking daft questions with me -
I'll be sticking with the 2.0 litre head as I've got a recently re-conned one with all new rockers etc, couple that with the fact that 2.5 heads seem at a premium due to cracking etc.

[Widge]

Cheers mate. I just happen to have a spare 2.5 engine so I thought the 2.5 head would be the best bet, now I come to think about it there is no difference is there it's all in the bore.

Ok silly question, if my 2.5 block is good is there any advantage to using the eta crank rods and pistons in the 2.5 block with 2.5 head?

Also as far as fuelling is concerned, just higher pressure and blue top injectors and 2.7 chip? no larger injectors needed?

An lastly, is it possible to skim the head or block to get a bit more compression? or am I better to shove a shrick cam in for a bit more grunt?
Thanx

[Widge]

Presumibly as I would be using a BBTB and chip, and the engine would be basically reconditioned, the MPG would be similar to a 2.5 as there is plenty of torque (I'm talking about long run Mway driving) and smaller throttle openings would be needed to achieve the same speeds.
When razzing it I should think the MPG would be bad ish but not a lot worse than a wornout M20. My current engine has done 17000 but is still going strong, however I should think it is far from factory power out put or MPGs.

[Jimbob]

Cheers mate. I just happen to have a spare 2.5 engine so I thought the 2.5 head would be the best bet, now I come to think about it there is no difference is there it's all in the bore.

Ok silly question, if my 2.5 block is good is there any advantage to using the eta crank rods and pistons in the 2.5 block with 2.5 head?

Also as far as fuelling is concerned, just higher pressure and blue top injectors and 2.7 chip? no larger injectors needed?

An lastly, is it possible to skim the head or block to get a bit more compression? or am I better to shove a shrick cam in for a bit more grunt?
Thanx

If using the eta crank and rods then you're gonna need the block shaved anyway.

[Widge]

What advantage is there to using the eta crank and rod and getting the block shaved? or should I just put the 2.5 head on the eta block?
Will I have valve clearance problems if I use a shrick 288/278 on it?
Cheers

[Widge]

Guys, if you read this article it seems that you need 'i' pistons with the 'i' head.
http://www.bmwe30.net/cgi-bin/datacgi/d ... Section=03
Or does that not count if you get a high comp 'e'??

[Andy_magic]

Hi Andy, yes the 2 litre head fits perfectly and has the exact same combustion chambers as the 525e head but with bigger ports.

The 325i head must be different.

[M5pilot]

One of the giveaway reasons why the 320i is suited to the ETA bottom end is because the 320i bottom end has flat top pistons which are also used in the ETA lump.

325i head designed to work perfectly with 325i bottom end which has domed pistons.

320i head on ETA lump should work well.

[Widge]

Ok thats useful info, but the domed combustion chamber and piston set up gives more power genrally. so would it be possible to put the 2.5 pistons on the eta bottom end and block with the 2.5 head? Surely if this could be made to work it would give the best gas flow, because the 320 head must have smaller ports etc compared to the 2.5.
I'm just asking as I know a guy who can do machining so having the block, head or the pistons (well maybe not!) machined does not bother me aslong as it is going to give more bhps.

[Andy_magic]

Smaller ports gives higher gas velocity which gives more torque.

I'll be interested in how much difference there will be between a 320i "stick it together and see" 2.7 and a and expensive machining work 2.7 based on a 2.5.

I know the pukkha 2.7s have big power outputs but they cost thousands, my budget is limited, what ever it turns out like it's going to be quicker than the 2.0 litre engine that's in it now with nearly 180k on it.

I'm thinking i'll get about 175bhp and decent hike in torque with the right fuelling etc.

Does anyone know how much better the 2.5 cam is over the 2.0. The 2.0 litre feels very 'cammy' and comes on song at about 3.5k rpm all the way up to the limiter.

[Chaos]

been meaning to ask this for a while but forgot.

ive heard talk of early eta's being high comp and later ones being low comp, but what month and year did the low comp engine come in ?

And how is the difference made up, block or pistons ?

[Widge]

High comp is 10ish :1 low comp is 8.31:1 I think. Look at the article I posted above it should answer your question.

PS Chaos cheque didn't come today Bloody post
You planning a 2.7 too?

[JonnyBravo]

Hello there could be getting my hands on a 525e as well but half the work is done for me

ItÔš's a 525e but it has a 325 head/manifold/injectors/AFM/Cams already on it, I just seen it tonight and it has the 2.5 stamp on the side of the head but I donÔš't think the pistons where upgraded

The car is running fine part from 2 problems. 1. Automatic 2. ItÔš's still in the 525e with the 525 ECU so it donÔš't rev out right

The guy never got round to finishing it so heÔš's for selling it cheap to me

Was going to swap it over to my 1989 325i sport would there be any problems in fitting this to my car? Would anything need upgraded?

[Andy_magic]

from what i've read an eta block with an i head on will give 8.4:1 c/r (based on a 9:1 cat engine) which isn't high, but is well suited for forced induction but thats a whole different ball game.

[Widge]

I don't think there would be any problems, if i was you and the engine is sound I'd leave it and just bolt it to your sport box (you'll need to change the fly wheel) and get a zone 2.7 chip off ant when he's back. other than that I don't see any problems, you might as well get a BBTB if all that has already been done for you! you lucky git

In the eta with the eta ecu it won't perform at all cos the 2.5 cam only stars getting powerful when the eta ecu gives up. I would check the pistons now thinking about it otherwise you may end up with a less powerful engine as the flat topped pistons with the hemi combustion chamber will lower the compression ratio than the low compressin M20's.

[JonnyBravo]

i know very luck man every cloud has a silver lining lol my head gasket is leaking oil on the sport and i may be able to get this 525e for 350

wat sort of flywheel would i need to get? and any idea where from?

i get wat your sayin about the pistons, while she's out would it be a good idea to swap them over?

[Widge]

I fi was you I'd just put a 325 flywheel on it so it can hold a clutch!!
When I do mine i'm going to have the wheel lightened a bit.

As for the pistons, I'd crack the head off and have a look, if its hemi combustion chambers and flat pistons I'd definetly change them, otherwise you'll probably get the same power as the sport. and you'll have to have a new head gaskett, sump gaskett and rings (stick an oil pump in too) so there will be sod all to go wrong with it. piece of mind, do the timing belt too. That little lot will probably come to the same as a new head for the sport so you'll be ahead of yourself mate.
be a good project if you can do all that in the evenings then just spend a weekend swapping the engines over. plug and play!!!

[Chaos]

how does this sound ?

eta crank
early eta block
325i pistons
325i head


or wud u do it differently ?

[Widge]

I'm not really an expert so don't take this as gospell, but that sounds good, just assemble the block and then put plasticene on the pistons and put the head on crank it over and take the head off to see how much piston valve clearance there is. The thing is this set up would give you the right compression which is important to get the extra 2.7 power. But I'm not sure if the 2.5 and eta block are the same or not which is what I'm wondering about at the mo. my worry is that I want a shrick 288/274 cam as well and I think with the increased lift and period the valves may need cut outs in the pistons.
I dunno all the specifcs yet but I think I know enough to do an experimental assembly when I get an eta engine.

[Widge]

Smaller ports gives higher gas velocity which gives more torque.

They also throttle (no pun intended substitute strangle) the engine at high rpms' which if you are going to use a 2.5 cam is where the power will come.

[Templ8e30]

My mpg varies a bit - Town driving with hard blasts down the motorway to work =26mpg, long motorway journeys @90mph or country roads = 30mpg.

I used GSF for gaskets and seals, they are Elring the same make as the dealer supplied ones. If you look at the oil seals the bmw lettering is crudely scraped off !

The 325i cam has 8 degrees longer duration over the 320i cam and a slightly different profile.

The eta pistons and 325i head are not compatible because of the special shape of the 325i combustion chambers.

I also used a 320i flywheel, It might be a bit lighter than a 325i flywheel but I'm not certain.

And dont forget if you have the check computer you'll need an e30 alloy sump with the oil level sensor. The e28 525e sump is steel and doesn't have the extra lump at the side.

Cheers,

Iain T

[Widge]

So with the 2.5 block, head and pistons and eta crank and rods, there is no need to shave the block? That would make life easier.
Where did you get the piston rings from? GSF? And how about bearings?
Cheers
Mate

[Jimbob]

Order your bearings once you've seen the ones you've got - GSF only supply 1 type but there is another one which the machine shop managed to order in.
The difference being is one has a single indent on the side and the other having 2.

I have that combination you just said and will definately require machining, pistons included.

[Jimbob]

and yes I did get the piston rings from GSF.

[Widge]

Thanks
I'd be interested to hear what you have to have machined,
stick a post up with som ephotos when you get back from the
machine shop,
Cheers

[Jimbob]

Dude my car is running now

I have done a small write up at:

http://members.fortunecity.co.uk/e30jim

[Widge]

Ah legend cheers I'll have a quick look.
What sort of figures are you producing?

[Jimbob]

No idea on power output as I'm still running it in (150 to go!) so don't get to feel the full extent of the pull yet but it feels a shitload faster - everyone says the M42 is a revvy engine, but from the amount of torque this thing has it revs better felt when pulling off from lights etc

Done 850 miles so far, running in until 1000 then wil get it rolling roaded after 2000.