wanting to build a 2.7 stroker

[l0w320 0]

hello there guys

ive been doing a bit of research about the m20 2.7i stroker in the e30

theres defianatly alot of different bits of info out there

looking at doing this conversion within the next couple of months into my 320i

just wanting to know what peoples exact builds on here are was kind of leaning more towards frantiC since hes done the conversion but any information is much apprectiated

[Jeddy 0]

There are so many threads on this and info out there. Search 'stroker' and sift through the vast amount of info. Google is also your friend.

[Guest FrantiC]

I'll lay out my stroker N/A setup for you..

Stock 88 525e ETA m20 2.7 bottem end (ETAblock, ETA pistons, ETA rods, ETA crank). 88 Models had a standard 10.2:1 Compression ratio.

I then put a 885 head, which is the 325i e30 head. Everything but the block was from a 325i. All electrics (running motronic 1.3), Intake and exhaust manifolds, throttle body, AFM etc. I was using 17.5lb injectors (standard m20 are 14.5lb).

With the 885 head, the compression was dropped to around 9.5:1 due to a different combustion chamber design and the pistons not matching the head. Using the stock 325i ECU with 17.5lb injectors it ran pretty damn sweet and went hard. Awesome low down torque and high end power.

FYI the 17.5lb injectors are m50b25 injectors.

There are other ways of doing this, My way was the cheap way were you don't need to disassemble the block etc.

Another way you can do it is with the 731 head, (F/L 320i, or 323i head). Not as high flowing as the 885 head, but the combustion chamber matches the piston shape (same combustion chamber design as the stock ETA head) so the compression won't drop like it does with the 885, so with a stock 10.2:1 CR ETA and the 731 head, it will still net you a 10.2:1 CR.

Another way is by using ETA crank with 130mm rods, and 325i pistons with the 885 head. This way the 325i pistons match the 885 head, but the stroke vs rod ratio means the pistons TDC are 2mm bellow the deck, so you would need to mill the block deck down, then it needs an adjustable cam as the head sits lower down and it puts the cam timing out.

Or I am pretty sure there is a way of using ETA crank, 325i 133mm rods with 325i pistons, but the pistons need to be modified as the 3mm longer rods mean the pistons will go up too far and mash into the head with the longer stroke of the ETA crank.

p.s Sorry for any mis-information in here, pretty sure it's all about right though feel free to correct me anyhow. I done the cheap way myself with the stock ETA bottem end. Worked very well, I was happy with it.

[e30plz 1]

There are so many threads on this and info out there.

E30tech is pretty good for stroker info.

[l0w320 0]

I'll lay out my stroker N/A setup for you..

Stock 88 525e ETA m20 2.7 bottem end (ETAblock, ETA pistons, ETA rods, ETA crank). 88 Models had a standard 10.2:1 Compression ratio.

I then put a 885 head, which is the 325i e30 head. Everything but the block was from a 325i. All electrics (running motronic 1.3), Intake and exhaust manifolds, throttle body, AFM etc. I was using 17.5lb injectors (standard m20 are 14.5lb).

With the 885 head, the compression was dropped to around 9.5:1 due to a different combustion chamber design and the pistons not matching the head. Using the stock 325i ECU with 17.5lb injectors it ran pretty damn sweet and went hard. Awesome low down torque and high end power.

FYI the 17.5lb injectors are m50b25 injectors.

There are other ways of doing this, My way was the cheap way were you don't need to disassemble the block etc.

Another way you can do it is with the 731 head, (F/L 320i, or 323i head). Not as high flowing as the 885 head, but the combustion chamber matches the piston shape (same combustion chamber design as the stock ETA head) so the compression won't drop like it does with the 885, so with a stock 10.2:1 CR ETA and the 731 head, it will still net you a 10.2:1 CR.

Another way is by using ETA crank with 130mm rods, and 325i pistons with the 885 head. This way the 325i pistons match the 885 head, but the stroke vs rod ratio means the pistons TDC are 2mm bellow the deck, so you would need to mill the block deck down, then it needs an adjustable cam as the head sits lower down and it puts the cam timing out.

Or I am pretty sure there is a way of using ETA crank, 325i 133mm rods with 325i pistons, but the pistons need to be modified as the 3mm longer rods mean the pistons will go up too far and mash into the head with the longer stroke of the ETA crank.

p.s Sorry for any mis-information in here, pretty sure it's all about right though feel free to correct me anyhow. I done the cheap way myself with the stock ETA bottem end. Worked very well, I was happy with it.

sweet thanks john much appreciated.

ive also read somewhere about using my b20 head and just use the 885 intake manifold afm throttle body onto your 731 head? true or false??

because since i already have a b20 i was thinking of just using my head with bigger injectors as you said and the 885 intake manifold afm and throttle body?

[Guest FrantiC]

sweet thanks john much appreciated.

ive also read somewhere about using my b20 head and just use the 885 intake manifold afm throttle body onto your 731 head? true or false??

because since i already have a b20 i was thinking of just using my head with bigger injectors as you said and the 885 intake manifold afm and throttle body?

I guess you could, But there ain't much point (other than being able to run a bigger throttlebody) as the b20 (731 head if its a facelift) ports won't match up to the larger 325i intake ones, So in effect you will probably lose torque having bigger runners but no gain as the ports into the head are still small.

is your b20 facelift or pre-facelift? You want the facelift type one, which is the 731 (check casting number on the head, under the intake manifold side IIRC in the middle). Should end in 731. If it ends in 200, you have the earlier type b20 head which is no good, ports and valves and everything are much smaller so the gains will be alot less.

Edited October 29, 2009 by FrantiC

[skidz 197]

I guess you could, But there ain't much point (other than being able to run a bigger throttlebody) as the b20 (731 head if its a facelift) ports won't match up to the larger 325i intake ones, So in effect you will probably lose torque having bigger runners but no gain as the ports into the head are still small.

is your b20 facelift or pre-facelift? You want the facelift type one, which is the 731 (check casting number on the head, under the intake manifold side IIRC in the middle). Should end in 731. If it ends in 200, you have the earlier type b20 head which is no good, ports and valves and everything are much smaller so the gains will be alot less.

The 200 head is E21 and prior and was also used on the 525e. The 731 head should be on all other 320i / 323i E30 M20 motors. I understand you can match the 325 manifold ports to the 731 head, but have not done it myself.

[Deano 1]

The combo I used:

11:1 eta block

885 head

stock cam ( needs to be at least a 272 but will be putting in a 288 for those upper RPMs)

19lb ford yellow injectors from ebay

port matched stock manifolds

2.7 C2 alpina chip

new rings, bearings etc

M30 afm

Goes well, needs the cam but the torque is great.

The bad..only runs 98, old eta's collapse the skirts on the pistons and give you piston slap when cold...but I can live with it.

Best advice to you is build a 2.8

[l0w320 0]

ive got a face lift

alright thanks for the info guys do you have to run all 2.7 stroker builds on 98 :S

well going to start buying parts within next month or so.

so if anyone has any of the parts give me a pm

thanks

[charles28 136]

ive got a face lift

alright thanks for the info guys do you have to run all 2.7 stroker builds on 98 :S

well going to start buying parts within next month or so.

so if anyone has any of the parts give me a pm

thanks

The good news is, you can use the 320i's ECU, all you need is another chip for it to run the bigger engine properly.

I would suggest not using the 731 Head, my 2.7 had this, it didn't like revving much over 5500rpm with a 323i Cam.

This was port matched to the 325i Intake manifold also, so that wasn't an issue, my car now has a factory 325i engine back in it and its nicer to drive and revs out alot better, the 885 head is a much better option, thinking about it, I wouldn't bother with the 2.7 anymore, all these ETA blocks are 22-25 years old +, most will need a good rebuild, better off getting a good 325i engine and getting a 2.8 Crank from a M52B28 engine, you can use your 320i rods with 325i pistons and 2.8 crank. with a good cam you could see 210-220hp with this.

, get the radiator checked when the cars apart, alot of them test as being quite blocked even when they look in good condition.

Edited October 30, 2009 by Charles28

[l0w320 0]

The good news is, you can use the 320i's ECU, all you need is another chip for it to run the bigger engine properly.

I would suggest not using the 731 Head, my 2.7 had this, it didn't like revving much over 5500rpm with a 323i Cam.

This was port matched to the 325i Intake manifold also, so that wasn't an issue, my car now has a factory 325i engine back in it and its nicer to drive and revs out alot better, the 885 head is a much better option, thinking about it, I wouldn't bother with the 2.7 anymore, all these ETA blocks are 22-25 years old +, most will need a good rebuild, better off getting a good 325i engine and getting a 2.8 Crank from a M52B28 engine, you can use your 320i rods with 325i pistons and 2.8 crank. with a good cam you could see 210-220hp with this.

, get the radiator checked when the cars apart, alot of them test as being quite blocked even when they look in good condition.

oh well ill just have to see what parts i can get at the time :S i have a bit of thinking to do now

[QuickSilver 0]

The good news is, you can use the 320i's ECU, all you need is another chip for it to run the bigger engine properly.

I would suggest not using the 731 Head, my 2.7 had this, it didn't like revving much over 5500rpm with a 323i Cam.

This was port matched to the 325i Intake manifold also, so that wasn't an issue, my car now has a factory 325i engine back in it and its nicer to drive and revs out alot better, the 885 head is a much better option, thinking about it, I wouldn't bother with the 2.7 anymore, all these ETA blocks are 22-25 years old +, most will need a good rebuild, better off getting a good 325i engine and getting a 2.8 Crank from a M52B28 engine, you can use your 320i rods with 325i pistons and 2.8 crank. with a good cam you could see 210-220hp with this.

, get the radiator checked when the cars apart, alot of them test as being quite blocked even when they look in good condition.

I know you had a bad experience with your stroker, however I dont think this means that all E blocks are going to be crap, as we have all learnt years, or age on a motor or car in general are often irrelevant, it's all about how its been treated, if proper care has been taken, or if its been thrashed to hell and back. There are good blocks around and a stroker is a good value for money upgrade.

[Guest FrantiC]

Indeed. My ETA block had 66,000kms when I picked it up, from a very well maintained 525e. Of course I had to pay abit to convince the guy to take it out of his car for me and disassemble it.

No you don't have to run on high octance gas, 11:1 CR with 885 head brings it down to about 10.2:1 IIRC? I'm guessing the fact the compression is still high means that you need to run on higher octane to avoid detonation. But I ran mine on 91, 95 when I could afford it lol.