Please help! 2.7 engine build spec, i'm confused!

[DORAS]

hi help!!!!

I have read all the posts on this conversion, I was alright to start with but the more I read the more variations I have seen.

I have just stripped the block from a 1985 525e, I want to use a 325 head (gas flowed), a fast road cam, larger throttle body, induction kit, 2.7 chip, standard exhaust manifold (at the moment) with full scorpion system, 325 inlet manifold, fuel pressure reg and injectors etc

I will be installing it into a 1989 325i sport (manual)

I am just trying to aquire another 2.5 engine so I dont have to immobilize mine while I build this 2.7.

I would really appreciate it if someone can give me a comprehensive specification to build this engine to. If i need a vernier pulley or to get the block decked or what ever so be it! I just want to get on and build it. I dont have a set budget but would like to come in under £1000 if possible.

also where is the best place to get rings and shells from??

p.s any ideas what sort of power figure i can expect????

Thanks in advance doras

[Conan]

A step by step guide and spec list would make a usalful addition to the tech articles.

[Jhonno]

good luck for under 1k..

you need to get a vernier pully as the block requires decking

[Simon13]

shells can be bought from bmw not alot of money.

try and get early 325i pistons, these will need matching too, some meat taken off the skirt to stop them hitting the crank

doing it for a bag? are u building it yourself then!

[DORAS]

yeah will be building it myself, if it costs more than a grand so be it!

why early 325, and what model year?

[Kos]

argos.....................where are you??

[Jhonno]

yeah will be building it myself, if it costs more than a grand so be it!

why early 325, and what model year?

pre 88

higher compression pistons.. if your gonna build it properly you might as well do it properly

[Ant]

Early pistons with a 2.7 crank gives 10.53C/R
Late with 2.7 gives us 9.5 C/R

the higher CR will(should) give more HP, but you'll need to be careful unless you plan to run 97-102 octane in the beast.

block must be decked if using anything other than the ETA pistons, or custom units, so the vernier is 100% required, and desirable in any case

I have seen a 2.7 built using VW type 1 pistons in the US same bore size available and very cheap in forged, maybe worth a sneaky peek in the Mahle book ??

[DORAS]

I live in Salisbury,wiltshire

so which block shalli use, eta or 325 with early pistons???

[Jon_Bmw]

I live in Salisbury,wiltshire

so which block shalli use, eta or 325 with early pistons???

Bloody hell another Salisbury lad, might have to come look at your progess. Can't interest you in a 325 turbo i guess?

[DORAS]

I think i know you, i think you bought some e30 stuff off me, interior??

[Simon13]

ok,

forget all the crap about using 2.0 heads eta blocks etc it's all sh!te

all u want is the eta crank, 320 rods, 2.5 block, 2,5 pistons early or late, 2.5 head, vernier pulley are all your main parts

The only way is to do it proper! imo don't go half way or cheap this cheap that.

Zoner built a 2.7 this way with a cam and early 2.5 pistons and put out 200bhp and lbs on the rollers no messing.

Get as much head work as u can done too!

[M5pilot]

If you are going to do this properly forget using the BMW pistons. Get some light weight pistons with your required CR - available from the states.

You'll save money on not having to machine the skirts on the early BMW pistons and possibly having to machine bigger cut outs.

The BMW pistons are heavy in comparison to some of the light weight stuff you can get out there.

Also remember to get a light weight fly wheel. Although this may not show any increases on dyno which calculates flywheel figures you will see a good 5-6 bhp increase at the wheels (which is what matters).

[Jon_Bmw]

I think i know you, i think you bought some e30 stuff off me, interior??

Oh yes, richard right?

[Dunx]

What C/R is desired for this conversion? - and do you still use the 325 block and 320 rods?

Was looking at a clutch - which said it would work with the 320 the 525eta - but not the 325???? - does the 325 stuff work with this? (ie flywheel etc)

[Simon13]

320's probably have a wanky clutch designed for 120lbs of torque

a standard bmw 2.5 clutch is good for serious power 2.7's so no need for after market there either

[rat]

ok,

forget all the crap about using 2.0 heads eta blocks etc it's all sh!te

all u want is the eta crank, 320 rods, 2.5 block, 2,5 pistons early or late, 2.5 head, vernier pulley are all your main parts

The only way is to do it proper! imo don't go half way or cheap this cheap that.

Zoner built a 2.7 this way with a cam and early 2.5 pistons and put out 200bhp and lbs on the rollers no messing.

Get as much head work as u can done too!

A legend in your own mind methinks

Not everyone needs absolute power at the end of the day - unless you want to compare slick lengths

DORAS - read argos/masterbates posts, you'll learn more that way

[M5pilot]

Rat,

what simon13 is saying is actually quite true. The 320i Head ETA block method is a bit of a wasted effort. I've driven a few cars with this configuration and while there may be a little extra torque the engine doesnt like to rev (even with a good cam) and is not as nice to use a lightly modified 325i engine.

There are quite a few cars that have used the 325i head, ETA Crank, 320i rods and uprated cam way and they have always made over 200bhp.

This method of getting 200bhp is very very well known and also very old now. I remember a guy with a red touring about 4 years ago who done it this way at home and got 204bhp.

Quaser's 2.7 Motorsport cab, Jimbob's 2.7 used the exact same method and both have broken the 200bhp barrier.

Going to correct route doesnt cost alot of extra money and is well worth the extra effort.

[rat]

M5 Pilot, I know what you're saying - the thing is not everyone has the money to go the whole hog.

Sure 200 is better than 190/180 - and yes, the basic 525e/320 route is a bit strangled.

And - how many engines has Simon 13 built?

[Ziggy]

Can anyone actually give me a definitive yes or no, to combining a standard UK ETA bottom end with a standard 325i head etc? As in would it be worth doing / significantly better than a standard 2.5. I had thought that it was a big NO, but recent suggestions seem to be otherwise... What was the engine that Masterbates built recently?

[Turbo-Brown]

320's probably have a wanky clutch designed for 120lbs of torque

a standard bmw 2.5 clutch is good for serious power 2.7's so no need for after market there either

Seems a standard 2.5 clutch is good for more than 240lbft and 270bhp too

[Simon13]

i'm no.1 so why try harder? the guy asks for advice so i'm giving mine

theres 2 types of peeps with cars people who do things properly, try their best and those who bodge. I'm sorry can't afford is a scape goat, try can't be bothered, too tight, too impatient to save etc

Rat do a 2.7 with a 2.0 head, it will feel like it goes better than a 2.5 but probably won't in reality. The simple fact is the engine can't breath and is strangled by the head.

Now masterbates has built a 2.7 by using a complete eta bottom end and slapped on a 2.5 head. He says it works too, which dispells alot of myths aout how too and what to use in a 2.7.

Rat are u an engine builder then for a living?

[Ziggy]

i'm no.1 so why try harder? the guy asks for advice so i'm giving mine

theres 2 types of peeps with cars people who do things properly, try their best and those who bodge. I'm sorry can't afford is a scape goat, try can't be bothered, too tight, too impatient to save etc

Rat do a 2.7 with a 2.0 head, it will feel like it goes better than a 2.5 but probably won't in reality. The simple fact is the engine can't breath and is strangled by the head.

Now masterbates has built a 2.7 by using a complete eta bottom end and slapped on a 2.5 head. He says it works too, which dispells alot of myths aout how too and what to use in a 2.7.

Rat are u an engine builder then for a living?

Now that sounds like a plan to me... I'll have to have a word with him & check, but if you're sure it's just an ETA bottom end I'll be needing, that's a result. I'm not against spending money where it's needed, but I'm not about to spend 1k plus on an m20. The only reasons I'm currently considering a 2.7 (as opposed to m50 / m30) are originality & so I can keep my exhaust manifold!

[Simon13]

well the more tuned the engine is the more that manifold will help!

good call, u might have to sell it to me if u go M30,M50

[TVRTASMIN]

Ziggy. The 325i block is stronger than the ETA. If you look at the casting, there is a big casting hole at the back plugged with a core plug. The 325i is smaller and hence stronger.
This is the only advantage imho so you could still use the block from the ETA.

M5Pilot. That red Touring could be mine. I got 210 BHP to start, but a larger TB and better filter has upped it slightly.

The machine shop that decked the block, shaved a tad too much off, plus i forgot to use a thicker head gasket. I can't use anything less than Shell Optimax or i get the rattles and black smoke when the pedal's to the metal.
I should see further gains once i fit the MS ECU which should arrive next week.

[StuBeeDoo]

The only way is to do it proper! imo don't go half way or cheap this cheap that.

In that case, why bother with the sh1te ETA crank? The proper proper way to do it is use the 324TD steel crank. Just ask Alpina or Hartge.

[chu346]

The 325i block is stronger than the ETA. If you look at the casting, there is a big casting hole at the back plugged with a core plug.

Not all have this core plug, mine doesn't.

In that case, why bother with the sh1te ETA crank? The proper proper way to do it is use the 324TD steel crank. Just ask Alpina or Hartge.

The only problem with that crank is that it would have a hard life from being shaken about from a diesel engine all its life.

[M5pilot]

325i heads will work with an ETA block.

I've seen pictures of a Les stannard 2.7 block and it uses pistons which are exactly the same shape as the ETA ones but they are just lighter.

Les stannard engines have proven to be very good!


If people dont have the money to do a 2.7 properly then there are better ways of spending the money to tune the 2.5. 2.5's are easily capable of getting 190-200bhp.

Take 1 healthy 325i which puts down atleast 165bhp standard and add:

Big Bore throttle Body
Good induction kit
Good 6 branch like the BTB's
Schrick 284/272 Cam
MAF conversion/MS/Standalone

If mapped properly you WILL get above 190+ BHP and a very nice fat torque curve. The noise will be rather tasty aswell.

[Brianmoooore]

Take 1 healthy 325i which puts down atleast 165bhp standard and add:

Big Bore throttle Body
Good induction kit
Good 6 branch like the BTB's
Schrick 284/272 Cam
MAF conversion/MS/Standalone

If mapped properly you WILL get above 190+ BHP and a very nice fat torque curve. .

That's cheaper than sticking a 320 head on an eta bottom end??

[320Touring]

Take 1 healthy 325i which puts down atleast 165bhp standard and add:

Big Bore throttle Body
Good induction kit
Good 6 branch like the BTB's
Schrick 284/272 Cam
MAF conversion/MS/Standalone

If mapped properly you WILL get above 190+ BHP and a very nice fat torque curve. .

That's cheaper than sticking a 320 head on an eta bottom end??

ouch easy tiger.

good point, well made though!

Si13, a 731head on an eta block is a cheap and reasonably easy route to obtaining more power and torque from an m20b20 lump. certainly if you have a 325i it'd be worth going the whole hog.

that doesnt mean that the 731 route is sh!te, its still a decent match for a stock 325i, which for us 320i owners is a substantial increase in performance.

not everyone wants to follow the crowd. doing that would make bmw tuning in general a bit boring.

[Jhonno]

the 325i heads are the same price from a scrappy and give more power so why bother with the 731 casting.. 731 would probably have a bit more bottom end, but would then be strangled at the top end

[Ziggy]

the 325i heads are the same price from a scrappy and give more power so why bother with the 731 casting.. 731 would probably have a bit more bottom end, but would then be strangled at the top end

Hegzactly

& if you've got a 325i, you've already got all the rest of the gubbins that go with it - better inlet mani, injectors, TB ( & BBTB soon in my case!)...

So who's gonna estimate what a swap of an ETA bottom end straight onto a 325i top end would make?

Doing that's got to be cheaper than a cam / MS etc? & there's obviously still the potential to do them later...

[StuBeeDoo]

In that case, why bother with the sh1te ETA crank? The proper proper way to do it is use the 324TD steel crank. Just ask Alpina or Hartge.

The only problem with that crank is that it would have a hard life from being shaken about from a diesel engine all its life.

Not true! That's excatly why the TD has a steel crank. It can take so much more of a pounding. A six cylinder diesel shouldn't "shake" any more than a petrol. And it will probably never been near 4.5k RPM. The biggest problem in the UK is sourcing one.

A couple of quotes from one of the BMW mags (can't remember which one, I only have photocopy of the article) on the subject of 2.7 conversions.............
1) The 525e crank.... designed to red-line at just under 5000rpm and plod along at under 3000rpm for most of its life. It's realistically safe to about 6200rpm, but there are stories of them twisting or even breaking across the webs at much over that. That's why Alpina used the diesel crank.
2) The 731 'head is far from shabby and can flow enough air for 200bhp.

In an engine which is producing max power at close to or maybe even a bit over 6k rpm, I think I'd rather not have a crank with a dubious rev capacity. Or put another way, 200rpm (or less) safe "over-rev" doesn't sound like enough to me. Particularly when the rev-limiter won't cut-in much before 6800.
As ever, anyone (Ant??) know any different and want to put me right, please feel free.

[M5pilot]

There are plenty, and I mean plenty of ETA based high power 2.7's around which rev cleanly to 7000rpm and never heard of stories of them twisting.

I'm not talking 200bhp cars either, Im talking about 230+ BHP m20's with ETA cranks which produced peak power at around 6800rpm!

So the stories of them twisting are utter nonsense.

The famous GUG has an ETA crank and we all saw that rev very very well.

[rat]

i'm no.1 so why try harder? the guy asks for advice so i'm giving mine

theres 2 types of peeps with cars people who do things properly, try their best and those who bodge. I'm sorry can't afford is a scape goat, try can't be bothered, too tight, too impatient to save etc

Rat do a 2.7 with a 2.0 head, it will feel like it goes better than a 2.5 but probably won't in reality. The simple fact is the engine can't breath and is strangled by the head.

Now masterbates has built a 2.7 by using a complete eta bottom end and slapped on a 2.5 head. He says it works too, which dispells alot of myths aout how too and what to use in a 2.7.

Rat are u an engine builder then for a living?

Hardly,

my first engine had the scrapers fitted upside down and I clipped the oill control rings to make em fit

Anty wonder Mr mountain turned my job app down