M50 Engine question

[ammar.alqisi]

We are buliding a bmw m50 engine with itb's , whats the best to use M52B28 crankshaft or M54B30 Crankshaft ? and why ?

[gdavid]

It really depends on your goals, parts access and budget, you need to use the corresponding rods and pistons for either crankshaft or it will they will be too tall and hit the head. Depending on parts availability and machine shop access, it may even make sense to bore it out and put s52 pistons in it for a 3.2 engine. What are you planning to do about cams? Are you thinking turbo or naturally aspirated? If you are doing a low cost build the m54 isn't nessisarly the best bang for your money unless the parts are very cheap.
I am doing the same thing.

[ammar.alqisi]

Actually am building a naturally aspirated engine for hill climb use, i have a ENEM camshafts, springs, valves, high compression pistons and SP Rods with ITB's and Link ecu for both engine, so what do you think ?

[gdavid]

Since you already have your pistons, you are pretty much locked into your stroke unless you have custom rods made the maximum allowable height to the block's deck is210 mm, where height = Stroke/2 + connecting rod + piston height. What is the height of you pistons and what rods are you using?