Need definitive answer re m50b28 (1997) crank

[Patto]

Stroker build parts take #2

Was originally intending on using ETA crankshaft and rods for build but have been told that decking the block isn't ideal and was recommended I change to an m50b28 crank. Engine is as follows.

M20b25 block and Bimmerheads SS885 head

325i pistons (0.50 over)
130mm rods
M50B28 crankshaft from 97 328i

I messaged MM regarding the required spacer and was told this setup will not work. Have also been told by a few local enthusiasts that they have used this setup and have been successful with some valve clearancing. RHD have said this setup would work. Finding it near impossible to determine who is right.

I have already got an 325e crankshaft and the rods, trying to avoid purchasing anything else incorrectly

If I can cannot get a definite answer looks like I'll just go back to the m20b25 rods and pistons and not bother with stroker. I have attached the reply from MM.

[digger]

It can be done 100%. The piston doesn’t pull through except maybe at 10,000rpm. In any case you can cut the crank to limit what you need to do to the piston I know a few guys in oz that used certain cranks that meant the crank didn’t need to be machined. As for skirts there are many types of skirt shapes

[Patto]

Thanks digger. I'm Australian based pistons I'm using are just oversized Mahle oem 325i 84.5mm. I had the feeling MM must have been misinformed after speaking to Rama RHD and a few other local builders. I actually sent you a massive inbox re this build as I saw you were Australian too. I'll grab the crank discussed and the ie seal adapted sleeve and get it all down to my engine builder.

[Patto]

Would it be best to get an E46 or E36 version? I read something about the dual vanos (E46 I assume) being harder to fit

[Patto]

Seems the message failed to send btw.

[digger]

I responded to that ? The earlier e36 iirc

[Patto]

Oh ok I just can't find it :)
What's E36 "irrc"? Sorry don't quite get the abbreviation?

[ForcedFirebird]

You need an early Euro m52 crank, and the crank counterweights clear just fine.

You will want to take .5mm off the block, since you added 9mm stroke (4.5mm up, 4.5mm down) and shortened the rods 5mm from b25 (75mm) status.

The USDM m52 cranks have larger counterweights than Euro counterparts. In 1995 USA demanded all cars use the new OBD (2) system, but elsewhere BMW could keep using non OBD (OBD1) with the CPS on the front of the crank.

The part number you need, and why, is listed in my other thread: https://www.r3vlimited.com/board/for...nd-2-8l-cranks

I have built many 2.8l's using the e36/e46 cranks. Have both turned the crank down and re-balanced them, as well as modified pistons. Not sure why MM would think the pins would pull put of the bosses, there's still over .250" left when clearancing the skirts. He might be thinking about the s52 crank - which MM has posted on their site about using smaller wrist pins in big stroked m20's. I haven't had any issues, and one of the b28's we built ages ago is still running around, making 215+whp on modified pistons.

[digger]

They say that so they can sell you parts