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Guest Anonymous

cross drilling crankshaft

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Guest Anonymous

Is cross-drilling the oil passages on the bearing journals necessary, or does the bmw bottom end do ok without it up to say...7500 to 7800 rpm?

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Guest Anonymous

I've never heard of that. I know few cars that run those figures so I don't think it's necessary. Can you explain what it means and what are benefits?

Tommy

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Guest Anonymous

by crossdrilling the crankshaft, you provide another passage for the oil to go through--where there was originally just one hole, there is now another one thats 180 degrees from the first. So when the crankshaft is spinning around in its happy little bearings, oil is distributed 2 times per revolution instead of just once...if that doesn't make sense...then I'll try to explain it later cause its friggin 1:30 am ;-)

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Guest Anonymous

basically at higher rpms you need some extra oil in the main/rod bearing department...I just don't know at what rpm I would start needing that extra oil--Thus, my post.

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Guest Anonymous

Yes, explanation makes sense. Would have think through the whole route the oil goes to figure out if that really helps. Makes me wonder if it's even possible to do for m10 shaft as drillings go diagonally from neck to neck.

Tommy

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Guest Anonymous

The bottom end will be fine. No cross drilling needed. The top end is the weak area. Having the right cam profile and valve springs to prevent rocker breakage is the primary concern with the M10 engine. G

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