Aluminum M52b28 info

[dirtdiggler]

Thinking of running the z3 aluminum M52 but was wondering if there were any real downsides vs the iron block? I would like to eventually do the budget stroker AKA M54b30 crank, rods,pistons any reason that would be a bad idea with the alloy block as well?

[ScotcH]

The big downside is that if you overheat it, it's done ... next downside is you can't bore out to bigger pistons (well, you can go up to 84.5mm). Is it worth the 40 lbs? Probably not unless you already have one ready to bolt in. I'd go for an m54b30 right off the bat, or just stick to iron block. You can run them on stock M50 ECU, but obviously standalone is the way to go.

[dirtdiggler]

The big downside is that if you overheat it, it's done ... next downside is you can't bore out to bigger pistons (well, you can go up to 84.5mm). Is it worth the 40 lbs? Probably not unless you already have one ready to bolt in. I'd go for an m54b30 right off the bat, or just stick to iron block. You can run them on stock M50 ECU, but obviously standalone is the way to go.

Why can you overheat the m54 but not the m52? what makes them different??

[ScotcH]

Why can you overheat the m54 but not the m52? what makes them different??

You can't but the m54 is much more common so if you do, it's easier to fix

[jakermac]

50 lbs, as measured by me. 1st pic is an M52B28 iron block from a 328is. 2nd pic is an aluminum M52B28 block from a 97 Z3. The 2nd pic is missing the bearing caps/bolts which I weighed as pretty much exactly 8 lbs.





I built exactly what you described, except with the goal of making as much power as I could without sacrificing low end power. M54B30/S52 crank that had been lightened from OEM 52lbs to 40lbs.



84.5mm 11.5:1 compression strutted lightweight pistons.

Molnar forged connecting rods.

Ported head

Metric Mechanic Rally grind cams

Tuned by Zack at 22RPD.com to make 270whp/240ftlbs torque on 94 octane pump gas.



I made some mistakes in the build. I suspect my biggest problem was that the crank was TOO light, and some weird harmonics were doing a number of undesirable things. I was running an ATI damper, but even that couldn't stop what ended up happening. Oh, and I was rev limited to 7,800rpm. I still got about 30,000 miles out of it before a fatal mistake made me tear the motor down to nothing and discover that I needed to do a whole lot more to make the engine healthy again. I decided to part out and go with my dream of a 4cyl turbo 500+whp build.

[ScotcH]

Yup, our early motor builds had lightened and knife-edged s52/m54 cranks … they didn't work. We've stuck with stock since, and happily run them to 7800/8000 rpm.

[pbonsalb]

What are the details for the 4 cylinder motor build?

[jakermac]

What are the details for the 4 cylinder motor build?

Honda K20A2 (2002-2006 RSX), KMiata K series to BMW ZF trans adapter/flywheel, forged internals, E85, TS EFR7163, 18-20psi.

[jakermac]

Yup, our early motor builds had lightened and knife-edged s52/m54 cranks … they didn't work. We've stuck with stock since, and happily run them to 7800/8000 rpm.

In hindsight I should have stuck with stock as well. But this was an autocross/daily driver build and I thought I’d get away with it since the high revs were going to be limited to 2nd gear (almost exclusively) and it would never see road course work with it’s extended high revs. Live and learn!

[pbonsalb]

In a 2800lb car, that 4 cylinder turbo will be a lot of fun and the fast spooling EFR7163 will give as much low to midrange as you can get from the 4 cylinder while still making 500rwhp. I have run the EFR8374 and 9180 on the S52 in my 3300lb M3 since I like response. I ran a laggy turbo for a year (GTX4088R) and made 677rwhp but did not enjoy the power.

Post the details when it is running and sorted out. I have a 73 2002 that I would like to swap a modern fuel injected easily serviced engine into. People have done M42/44 and I am leaning towards that but would consider a non BMW motor.

[jakermac]

In a 2800lb car, that 4 cylinder turbo will be a lot of fun.

In its previous life as an NA 3.0 build it tipped the scales at the SCCA Champ Tour event at Packwood, Wa in 2014 at 2,400 lbs. That’s built to Street Modified class rules that require most of the interior to remain intact.

[pbonsalb]

Wow! Any creature comforts remaining? AC? heat? Reclining seats? Sound insulation? Stereo?

[jakermac]

Radio/speakers/wiring gone.
AC gone.
Sunroof delete with 3lb CF panel.
Airbag and controller gone.
Rear seats gone.
2 no-slider CF 9 1/2lb buckets in the front - shockingly comfortable.

All carpet remains.
All door panels/rear panels remain.
Headliner remains.

Still a very comfortable daily driver (as comfortable as 850lb fr/900lb rr springs can be with good shocks)

Still 40-50 lbs that could come out with A LOT more effort. But I expect the new build will push the weight up 40-50lbs. Lighter motor, but intercooler, turbo, etc... But then my class is tacking on a 150lb weight penalty because I’m using a non-BMW motor. My min weight for power train (turbo 2.0) with the penalty will be 2,630lbs without driver. But there won’t be any ballast for daily driving, so good chance it’ll still be right at 2,400-2,450 on 285/30-18s for the street.

[dirtdiggler]

Radio/speakers/wiring gone.
AC gone.
Sunroof delete with 3lb CF panel.
Airbag and controller gone.
Rear seats gone.
2 no-slider CF 9 1/2lb buckets in the front - shockingly comfortable.

All carpet remains.
All door panels/rear panels remain.
Headliner remains.

Still a very comfortable daily driver (as comfortable as 850lb fr/900lb rr springs can be with good shocks)

Still 40-50 lbs that could come out with A LOT more effort. But I expect the new build will push the weight up 40-50lbs. Lighter motor, but intercooler, turbo, etc... But then my class is tacking on a 150lb weight penalty because I’m using a non-BMW motor. My min weight for power train (turbo 2.0) with the penalty will be 2,630lbs without driver. But there won’t be any ballast for daily driving, so good chance it’ll still be right at 2,400-2,450 on 285/30-18s for the street.

Wow thanks for all the good info,

Crazy I was also thinking going to k series but the only thing that made me change my mind was most likely having to move the steering rack.

Btw you really should make a build thread for the k20 project unless you have one somewhere?

[jakermac]

When I actually get started with the build I will most likely put up a build thread. Right now I’m still in the planning ($$$) stage. I have about 2/3rds of the stuff bought and the vast majority of the planning done. I’ve even got an idea or 2 that I’ve discussed with Sean from SLR Speed about moving the steering rack forward about an inch without altering the geometry at all, and I’m pretty confident that there’s room to move the engine back in the chassis about the same amount. Based on the pics I’ve seen of Alex’s build I suspect that’s all it’ll take.

And weight reduction wise, I’ve done a bunch more than what was listed above. All with the rule set in mind though.

[dirtdiggler]

Yes please do make a build thread as I'm sure many people would like to see something different. As far as the rack I'm sure Sean would be the go to guy so the steering will stay within OEM spec.

I have a few E36 cars and one of my "street cars" Has a 2jz and I was able to move the engine back about 1 1/4'' and the trans 2'' from where the M52 sat and that's without touching the firewall at all. I think the killer setup would be k24a2 bottom with k20a2 head so you have a little more torque.

[jakermac]

As much as I’d love to go 2.4 displacement, there are 2 negatives that come to mind:

Since my min weight is displacement based, I’d be faced with having to add another 80lbs, so my min weight would go up to 2710.

I am speculating that I’ll have trouble using the torque available with the 2.0 and the EFR7163 using 2nd gear at autocross. It’d be even more difficult with 20% more displacement.

[dirtdiggler]

As much as I’d love to go 2.4 displacement, there are 2 negatives that come to mind:

Since my min weight is displacement based, I’d be faced with having to add another 80lbs, so my min weight would go up to 2710.

I am speculating that I’ll have trouble using the torque available with the 2.0 and the EFR7163 using 2nd gear at autocross. It’d be even more difficult with 20% more displacement.

Very true points I forgot you car is for autocross