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      05-04-2013, 01:00 AM   #157
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Drives: 2011 E90 M3,1994 Euro E36 M3/4
Join Date: Apr 2006
Location: Fort McMurray, Alberta, Canada

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Originally Posted by VCMpower
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!
There is something wrong with the numbers you have given there!

If the engine makes 20-25 PSI at Idle and climbs to 60 PSI by 2000 RPM the pump makes lots of volume. It is not sensible to think that a positive displacement pump ( a positive displacement pump flows a fixed amount of fluid for each revolution, therefore the faster the pump spins the more flow it makes) will not make the additional flow over another 7400 RPM of engine speed to reach the relief valve setting!

From what you are explaining here, there is either an issue with the numbers (your claimed relief valve setting of 80 PSI), there is an issue with the pump, or there is an issue with the relief valve on that particular engine.

By the way, although it is not necessary in all cases since the stock oiling system is quite capable, there is a dry sump developed for the S65 that retains AC!
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Last edited by BMRLVR; 05-04-2013 at 01:39 PM.