M50b32 12:1

[st.petebiodiesel]

Before the build:
So I recently built a M50B30 stroker engine that was doomed from the get go. I was using a super worn M50B25 block, a set of used pistons and rods with the original rings (which I did not replace), I never fully removed the ring step at the top of each cylinder bore which caused all my top rings to snap and cause hella blow by.
This excessive blow by caused my dipstick to become unseated and jettison all the oil out of my engine on the highway. I stopped the car when the oil pressure light illuminated, but by then it was too late. 2 weeks later my engine had developed a very serious rod knock.
So due to my own stupidity my engine was fucked.


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[The Dark Side of Will]

So you want to do it over better?

[st.petebiodiesel]

M50b32 12:1

The build:
So now with a worn M50 block and trashed 89.6mm crank I made the decision to re rebuild my engine.
Originally I was going to buy a set of Chinese ebay M54 oversized pistons and have the block honed. I couldn't really afford BMW oversized pistons, but found a new set of S52 CP pistons on bimmerforums for half what they sell for from VAC. 12:1 compression!!

I ended up picking up a perfect M54B30 crankshaft at the junkyard for $50, it only took an hour to pull since someone did me a favor and removed the trans in the car at the yard.

I then sourced some M54B30 connecting rods on eBay for $60 shipped.



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[digger]

Sounds like a good project

[pazi88]

.
Originally I was going to buy a set of Chinese ebay M54 oversized pistons and have the block honed. I

Are these really a thing? I have tried to find cheap chinese pistons. With no luck.

[st.petebiodiesel]

Are these really a thing? I have tried to find cheap chinese pistons. With no luck.

https://www.ebay.com/itm/151234887719

It says in the description that they sell .50mm oversized and to just leave a note when purchasing.
1 oversized piston from BMW costs about the same as this entire kit of 6.
pazzi88 I love your YouTube videos.


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[digger]

seriously dont buy cheap chinese pistons

[LateFan]

seriously dont buy cheap chinese pistons

Sounds like an explodomat at 12:1

[st.petebiodiesel]

I'm sure they'd be fine for most builds, but I went with the CP Carrillo piston. 12:1 is pretty high for a street car, but I'll go into how I successfully resolved this in later posts.
These pistons are the shit though.


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[digger]

there is a lot that goes into a piston, even some of the aftermarket made in USA stuff isnt that great compared to an OE mahle/KS

[AWDBOB]

I am quite interested in this, as I have M54 internals currently going into an M52.

So M52 and S52 deck height is the same, correct?

M54b30 and S52 stroke is the same, correct?

So you are essentially using an M54 crank/rods and opening the bore up from 84mm to 86.4mm to get the 3.2L over the 3.0L you had with the full M54b30 rotating assembly?

If that's the case I'll just grab S52 pistons and open up the bore of my M52 block so I can gain the extra displacement.

Do you know if M54b30 rods use 22mm pins?

If the above is true, these 11.3:1 Mahle's would work perfectly.

[st.petebiodiesel]

I am quite interested in this, as I have M54 internals currently going into an M52.

So M52 and S52 deck height is the same, correct?

M54b30 and S52 stroke is the same, correct?

So you are essentially using an M54 crank/rods and opening the bore up from 84mm to 86.4mm to get the 3.2L over the 3.0L you had with the full M54b30 rotating assembly?

If that's the case I'll just grab S52 pistons and open up the bore of my M52 block so I can gain the extra displacement.

Do you know if M54b30 rods use 22mm pins?

If the above is true, these 11.3:1 Mahle's would work perfectly.

Those look like a proper set of pistons. I see they are .2mm oversized.
-Yes M54B30 crank/rods+S52 pistons = 3.2L
-Yes all wrist pins are 22mm throughout the M50-M54 engine families.
- All the steel blocks are the same in regard to deck height and cylinder wall thickness. Some claim that an S52 block has thicker cylinder walls,but I doubt it.
- My advice for anyone wanting to do a M50B30 stroker is don't try to put standard size M54 pistons into a M50 block. Even with new rings, the piston to cylinder clearance won't be tight enough unless you have a primo M50 block with no cylinder wear at all. You can tell by the ring step at the top of each cylinder how worn of a block you have. Also if you don't remove that ring step in the bore when building a stroker you will break your upper piston ring since the ring now travels up higher in the bore.
- It makes more sense to just go to the biggest bore available (unless your trying to run big boost).



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[st.petebiodiesel]

M50b32 12:1

I drove all the way from Tampa to Daytona to score some S52 Cams since the stock ones wouldn't do with this build. I actually had a M54B30 intake cam on my old engine which I later sold to pay for the machine shop bill.

As most used cams go this one needed some deep polishing.

I eventually want to get some Schrick 276/270 cams since my pistons will accommodate them without a vanos limiting shim.


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[digger]

yeah you want decently deep valve pockets so if you use bigger cams you dont need to limit vanos. ive heard a few say they needed to do this.

[AWDBOB]

Those look like a proper set of pistons. I see they are .2mm oversized.
-Yes M54B30 crank/rods+S52 pistons = 3.2L
-Yes all wrist pins are 22mm throughout the M50-M54 engine families.
- All the steel blocks are the same in regard to deck height and cylinder wall thickness. Some claim that an S52 block has thicker cylinder walls,but I doubt it.
- My advice for anyone wanting to do a M50B30 stroker is don't try to put standard size M54 pistons into a M50 block. Even with new rings, the piston to cylinder clearance won't be tight enough unless you have a primo M50 block with no cylinder wear at all. You can tell by the ring step at the top of each cylinder how worn of a block you have. Also if you don't remove that ring step in the bore when building a stroker you will break your upper piston ring since the ring now travels up higher in the bore.
- It makes more sense to just go to the biggest bore available (unless your trying to run big boost).



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I appreciate the response. I agree in regards to the bore- it makes great sense to go 87mm while you're at it, which would make it almost a 3.3L.

Wondering if folks have used the JE 11.5:1 S52 pistons. I've used JE in the past in the 4g63 world with success but haven't found any reviews of those using them in this community.

https://www.ecstuning.com/b-je-piston-parts/87mm-pistons-60mm/je297173~jep/