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528e stroker

E28 technical advice asked and given! Troubleshooting, modifications and more.
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simon wilhoit
Posts: 4
Joined: Feb 19, 2025 11:43 AM
Location: Greeneville, TN

528e stroker

Post by simon wilhoit »

I’m new to this forum. I have a 87 528e and would like to stroke it. Does any have a parts list for stroking a 2.7? Thanks 
turbodan
Posts: 9366
Joined: Jan 09, 2007 10:19 PM

Re: 528e stroker

Post by turbodan »

I've never seen it done but I've heard of using an M54B30 crank. An S50/52 crank may be an option as well.

If it turns out to be an absolute barn burner of a success you might expect 200 at the rear wheels, a little bit less than a standard S50/52. That's going to require a more aggressive cam, head work, high compression, standalone efi and good headers.

180-190 is more likely and I don't know if the juice is worth the squeeze. Turbocharging is cheaper and will make great green gobs of horsepower and torque, without compromising fuel economy and reliability. Something to consider...
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: 528e stroker

Post by Mike W. »

In a sense the 2.7 is already a stroker. The other M20 displacements were 2.0, 2.3 and 2.5. M5x engines are kind of M20s with a 4 valve head, and like Turbodan I've heard of one of those cranks being used in an M20, but never seen it.

An E30 forum might, or might not, have more info.
kojo96
Posts: 923
Joined: Mar 31, 2019 7:39 PM
Location: Pleasanton CA

Re: 528e stroker

Post by kojo96 »

Search is your friend. Here's a detailed build on how to make a 2.9 liter stroker. 

viewtopic.php?t=121687
Last edited by kojo96 on Feb 20, 2025 1:18 AM, edited 1 time in total.
Foonfer
Posts: 771
Joined: Mar 18, 2015 11:33 PM
Location: New York, NY

Re: 528e stroker

Post by Foonfer »

1. Search is your friend.  Look for "e to i conversion" or "e2i" in addition to "stroker".
2. One of the most authoritative pages on the topic is (or used to be) this one: https://strictlyeta.net/technical/328i/
3. Before you do anything, you need to ask yourself WHY you want to do an "e to i" conversion (I know one reason: because you think your 528e is too slow, and you want MOAR PWWRR).  Now, the "e to i" conversion probably sounded like a great idea way back when.  At that time, the 528e made 121hp and the benchmarks were the 535i at 180-ish hp and the ultimate goal was the M5 at 285hp or so.   These days, an Honda Civic makes more power than the E28 M5, and 400hp is almost regarded as "entry level" for enthusiast-grade cars.  It is a whole different ballgame.
4. The "e to i" conversion sounds like it is not as costly, but much more labor-intensive and parts-intensive (and you have to look for many "correct" parts, and there's quite a bit of spread among opinions of "what is correct").  With a pre-1988 car like yours, one of the key parts you'll have to source is an 885 head, which came in the 1988 528e and in the 325i's of the era.
5. All of this is to end up with a motor that makes between 170 and 200hp, 200 being very optimistic. The result will depend on many many many factors, the most important of which will be how much of your time, and your money, are you willing to invest into this project.
6. Advantages of doing an "e to i conversion":
   a) You retain your original engine, which is lighter than an M30 - this is not a small thing, originality fans are onto something
   b)  Not only is it lighter in weight, the M20 is much more economical at the pump than any M30-powered BMW.

So yeah.  First is ask yourself (and answer the question) - WHY do you want to do an "e to i" or "stroker" conversion.
Last edited by Foonfer on Feb 20, 2025 8:48 PM, edited 1 time in total.
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: 528e stroker

Post by Mike W. »

Foonfer wrote: Feb 20, 2025 12:10 AM
With a pre-1988 car like yours, one of the key parts you'll have to source is an 885 head, which came in the 1988 528e and in the 325i's of the era.
Are you sure that's the right head? I thought cars before super e's used an earlier and harder to find head. A 323 head maybe? Not an M20 expert, but I'd do an e to i conversion, whichever head it is, in a heartbeat. A 40-50 HP bump won't make it fast by todays standards, but it will allow it to get out of the way.
///M
Posts: 103
Joined: Apr 17, 2009 11:21 PM

Re: 528e stroker

Post by ///M »

The head for most airflow is the 885 head. It was fitted to the 325i. It was a big improvement on the older heads including the 323i head. The older head was from memory a 200. Tuners at the time could not match the airflow of the 885 on the previous heads the ports were just to small.

The Euro conversion/stroker is the 528e (eta) crank or the crank from a diesel m20 which was a forged crank. This was supposed to be the crank Alpina used. This was the nominal 2.7 litre. It used the 325i pistons and the 2.0 litre or the standard eta rods. The block needs to be decked to get the correct compression ratio
Another option is the crank from the M52 2.8 this crank fits and the 325i pistons and rods can be used giving nominal 2.8 litre. The piston skirt can need to be machined depending on if they are high or low compression. With low compression pistons the block is not decked. High compression pistons give a higher than standard compression.
A spacer needs to be added to the front of the crank for the oil seal to run on.
The S52 crank would be similar and easiest with an even longer stroke giving highest displacement.( not an Euro market car)
The crank from the 3.0 litre M54 is a little more involved.

BMW = Lego just mix and match the parts with a sprinkle of modification.

To put it in perspective back when the first 325i came out it had 171 hp (Euro) A tuning company in the UK offered a conversion of a 2.0 which produced slightly less hp and cost £5000. I bought a 325i engine from a crashed car for around £1000 and fitted it to a 2.0 so more hp for less money.
It depends on what you want to achieve and at what cost. 
 
turbodan
Posts: 9366
Joined: Jan 09, 2007 10:19 PM

Re: 528e stroker

Post by turbodan »

Mike W." wrote: Feb 20, 2025 1:00 AM
Foonfer wrote: Feb 20, 2025 12:10 AM
With a pre-1988 car like yours, one of the key parts you'll have to source is an 885 head, which came in the 1988 528e and in the 325i's of the era.


 
Are you sure that's the right head? I thought cars before super e's used an earlier and harder to find head. A 323 head maybe? Not an M20 expert, but I'd do an e to i conversion, whichever head it is, in a heartbeat. A 40-50 HP bump won't make it fast by todays standards, but it will allow it to get out of the way.
You are correct, the head that matches the 82-87 pistons is the 731. Used on the 320i and 323i. It uses the same valves as the 200 but with larger ports.

The 885 has 2mm larger valves but requires matching pistons to maintain an appropriate compression ratio.

The fuel injection is the big hurdle on the pre-88 cars. There is no chip for the eta motronic that will make it run right. I'm also not confident in the rings used in the 82-87 eta. They were a low tension design that is unable to control oil consumption at high RPM. The super eta and B25 used better rings which resolve the issue.
simon wilhoit
Posts: 4
Joined: Feb 19, 2025 11:43 AM
Location: Greeneville, TN

Re: 528e stroker

Post by simon wilhoit »

I really appreciate all the info from everyone. The question of why e to i conversion is weight and it just seemed to be easier than a 3.4/3.5 swap with the intent of turboing it down the road. I know parts are becoming harder to come by.300hp would be the max amount I would want. I’m looking to build a fun drifter. If someone has turboed one of these with decent success I’m all ears. I had a 528e when I was younger and loved it and had the opportunity to pickup 3 recently. 2 84’s and 1 88. I’m restoring one and want the other one as a whip with one being a doner due to wreck damage. I’d buy them all if I could 😆 I love these cars
simon wilhoit
Posts: 4
Joined: Feb 19, 2025 11:43 AM
Location: Greeneville, TN

Re: 528e stroker

Post by simon wilhoit »

Foonfer, that was an excellent thread. Thank you
turbodan
Posts: 9366
Joined: Jan 09, 2007 10:19 PM

Re: 528e stroker

Post by turbodan »

simon wilhoit" wrote: Feb 20, 2025 4:58 PM I really appreciate all the info from everyone. The question of why e to i conversion is weight and it just seemed to be easier than a 3.4/3.5 swap with the intent of turboing it down the road. I know parts are becoming harder to come by.300hp would be the max amount I would want. I’m looking to build a fun drifter. If someone has turboed one of these with decent success I’m all ears. I had a 528e when I was younger and loved it and had the opportunity to pickup 3 recently. 2 84’s and 1 88. I’m restoring one and want the other one as a whip with one being a doner due to wreck damage. I’d buy them all if I could 😆 I love these cars
There have been numerous turbo builds. Most on here were M30s but I believe the M20 is actually a better platform for a variety of reasons. Reliability, fuel economy and weight are a few of them. 

I have run in excess of 20 pounds of boost reliably with the stock M20 motor, down to the headgasket. My current build is going on two years in March. There is a fairly thorough build thread in the Forced Induction section. 
simon wilhoit
Posts: 4
Joined: Feb 19, 2025 11:43 AM
Location: Greeneville, TN

Re: 528e stroker

Post by simon wilhoit »

Thanks turbodan. After looking at your project and some YouTube videos I think I’m going to go the turbo route. I really appreciate you guy’s leading me in the right direction as I learn to navigate this site and great job on this website guy’s 
turbodan
Posts: 9366
Joined: Jan 09, 2007 10:19 PM

Re: 528e stroker

Post by turbodan »

It's a way better route than any NA build, bang for the buck and reliability wise. You can make 300rwhp reliably and efficiently with boost. Never going to get close to that NA, no matter how much you are willing to trade off for it.

 
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