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      05-03-2013, 08:35 PM   #156

Drives: 2010 Dakar, 2013 Fire Orange
Join Date: Jan 2010
Location: Victoria B.C.

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Thanks. I do know of a LC motor that has been set to .002 and those are real specs I gave you. So you have a little more info if you wish to take it. It does not reach above 60 psi at that clearance. This is why I was curious if you were thinking a dry sump setup where you can achive different pressure/flow. Taking another S65 apart on Monday so I will let ya know what clearances are there and condition of bearings. It is a 2008. That is quite amazing if that is all Dinan is doing and maintaing pressure. If I remember correct BMW provided thinner shells for the S54 and a larger volume oil pump.

Originally Posted by BMRLVR View Post
Generally speaking, oil clearance does drop as oil clearance increases hence that is the reason why engines lose oil pressure if main and/or rod bearings are worn excessively.

20-25 PSI is lots of oil pressure at idle (40 PSI actually a fairly high number at idle) if that is even the number that the S65 engine would have at .002". I have never seen anyone test the oil pressure on an S65 with .002" main bearing clearance but would look forward to the numbers. As for your maximum pressure, that is going to be set by the system relief valve......... if the relief is at 80 PSI, once the pump makes enough flow to go over relief it will still achieve that same 80 PSI that you state, it may just take a few more RPM to get there........ the principles of hydraulics are universal pressure is the resistance to flow and more flow equals more pressure. Flow increases as the oil pump RPM increases(oil pump speed is tied directly to engine RPM) which is why there has to be a system relief to protect the system from overpressure since the oiling system on the S65 uses a positive displacement pump.

FYI: Dinan sets the main bearings to .0019" and the rods to .0025" on their strokers....... I obtained this information while shopping for a stroker! Obviously they see an issue with the tight OEM clearances and they don't see an oil pressure issue with adding a bit of clearance to the Mains and Rods since they use an OEM oil pump!