Help required 2.1 stroker

[bigdogcb]

Hi all,
OK, I have several components ready to start the build of an M42 stroker, but I need some advise, and I hope someone out there can assist.
I have STD M42 block and head, the correct M47 long nose crank, 3.2 M3 pistons and rods. The questions I have are as follows:

1. what main bearings should I use for the M47 crankshaft?
2. What con rods should I be using with the 86mm 3.2 M3 pistons and the M47 crankshaft?
3. What height should the pistons be reduced by to obtain a near STD compression ratio?
4. What should the block be bored to in order to accept the 86mm 3.2 M3 pistons?

If anyone has this info then I would apreciate a little assistance.
Thanks in advance.

[Rallyprep_UK]

Hi, I have been building up the parts to do a similar thing.

I was wanting to keep it 2000cc or under using s50b30 pistons for competition class reasons.

I have so far
M42B18 engine complete
S50B32 throttle bodies and plenum
S50B30 pistons

Still need
some cams
Aftermarket ECU
M44 Rods (lighter)
Manifold
E30 M3 or similar/custom exhaust
Rebuild parts (gaskets etc)

I plan to remove the 3rd and 4th bodies and re-assemble as a set of four. To chop the 1st and 6th ends from the plenum and weld the ends up.

there is some good info here - http://the325is.blogspot.co.uk/2011/12/ ... -euro.html

I hope this helps !

Will

[ajay]

What crank will you be using? Out of curiosity.

[Rallyprep_UK]

M44 crank - 83.5mm stroke
S50B30 pistons - 86mm

Total displacement 1940cc according to the cc calculator, which puts me right up in the 2000cc class

3.2 pistons would take it to 1958.5cc but the 3.0 ones I got for free so I can live without the extra 18.5cc .

Will

[Rallyprep_UK]

More info here - http://forums.bimmerforums.com/forum/sh ... p?t=433471