Alluminum m52

[erik325i]

What kind of power should I expect to have if I build up an alluminum block m52 with an s52 crank? From what I've been reading, that should put the total displacement at 3.1L if I keep the stock bore size.

Would I be able to use the stock pistons, or would there be clearance issues due to the longer stroke?

The motor will be built to OBDI, will have Schrick cams, and a euro HFM

Does this sound like a good idea, or am I just building a timebomb?
Would I be better off building my s50 to 3.2L? I'd like to keep it as light as possible, but don't want to sacrifice too much power or durability.

-Erik

[2002maniac]

The M52 is a square motor 84mm bore and stroke

The S52 is 86.5x91 IRRC

That means if you put a S52 crank into an M52 the pistons would be 3.5mm above the deck.

You could have a machine shop deck the pistons 3.5mm and open up the valve pockets but you would lose most of the dish in the piston and the CR would be insanely high (someone should do the math to be sure though, it could possibly be manageable).

I just finished a set of S52 pistons for my m42 stroker and by decking the pistons 2mm the Piston dish went from 17cc to 10cc.

If you got custom pistons and had the final CR around 11:1 you would make TONS of power with schrick cams and the other mods you listed.

I would expect at least 240-250 at the wheels.

[2002maniac]

You should ask on Bimmerforums. They have alot more experience and knowledge.

I'm sure somebody has done an S50 crank in an M52, but that is only 85.9mm so it wouldnt be much of a gain.