Need some hard facts here reguarding M50B25 boring/stroking.

[parad0x]

the 1992 E36 325 M50 non-vanos block, having the thicker block compared to to other E36 93-95 models, has a bore/stroke of 84/75.

1995 M3 S50b30 has bore of 86/86.

The 1997 M3 S52B32 with a bore/stroke of 86/89.662

Having read all that I have, I have heard pretty much everybody tell me the M50 motor is thicker, and can be bored out easily to 86. Is this really the max? how much can I bore it out to, to make the left-over thickness of block to be similer to that of what is found on the stock 1995 M3 block? Another question is.. Wouldn't it simply be possible to swap in a 1997 crankshaft into the 1992 325, and bore the block out to 86 mm giving it 3.2 litre displacement? If I cant swap in this crankshaft from the 97 m3, how about the 95 m3? I believe that would still net me a 3 litre displacement with the 86 bore?

[e36'n]

the 1992 E36 325 M50 non-vanos block, having the thicker block compared to to other E36 93-95 models, has a bore/stroke of 84/75.

1995 M3 S50b30 has bore of 86/86.

The 1997 M3 S52B32 with a bore/stroke of 86/89.662

Having read all that I have, I have heard pretty much everybody tell me the M50 motor is thicker, and can be bored out easily to 86. Is this really the max? how much can I bore it out to, to make the left-over thickness of block to be similer to that of what is found on the stock 1995 M3 block? Another question is.. Wouldn't it simply be possible to swap in a 1997 crankshaft into the 1992 325, and bore the block out to 86 mm giving it 3.2 litre displacement? If I cant swap in this crankshaft from the 97 m3, how about the 95 m3? I believe that would still net me a 3 litre displacement with the 86 bore?

Here's what I know:

You can bore the non-vanos block to 86mm no problem. I've been told by numerous people that you can also bore to fit the s50 oversized pistons which are 86.565mm.

With a s50 crank and pistons you would have a 2.99 or 3.0 L. With the oversized pistons I believe it bumps it up to 3.03 L. If you choose the s52 crank and pistons 3.2L although I don't know if the s52 pistons fit.


What I'm trying to figure out is if you can use a s50 crank with the stock 84mm pistons and rods....I have searched for months and still nobody is 100% certain.

[parad0x]

Here's what I know:

You can bore the non-vanos block to 86mm no problem. I've been told by numerous people that you can also bore to fit the s50 oversized pistons which are 86.565mm.

With a s50 crank and pistons you would have a 2.99 or 3.0 L. With the oversized pistons I believe it bumps it up to 3.03 L. If you choose the s52 crank and pistons 3.2L although I don't know if the s52 pistons fit.


What I'm trying to figure out is if you can use a s50 crank with the stock 84mm pistons and rods....I have searched for months and still nobody is 100% certain.


Why would you want to find out if a S50 crank could fit, if it would be better to put in a S52 crank which would give you 3.2 displacement instead of 3. I think it would be better to find that out.. And regarding the S50 crank and M50 block, I've heard posts in where some have stated it would fit.. but I dont know how reliable that information was. But again, if you and me are going to spend the money to upgrade the crank, why not go full out and get the S52 crank? That would be our better alternative.

[e36'n]

The reason I want to find out if the s50 crank will fit, is because I have one. I would have gotten a s52 crank but it was around $400US more.

[parad0x]

The reason I want to find out if the s50 crank will fit, is because I have one. I would have gotten a s52 crank but it was around $400US more.


for a 0.2 litre increase in displacement, 400 bucks is worth it! that could possibly transalte to like 20-25hp more ;)


Come on, somebody has gotta know more regarding this...

[e36'n]

I disagree. It would be waaay more than $400us in the long run b/c you have to get custom pistons too when you go with the s52 crank. 0.2 L of displacement doesn't necessarily translate into 25-30hp. Maybe 10, maybe more...who knows.

No one has really done a comparison of the two swaps so it'd be hard to say.