 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | 04-01-2008 |
| Location: | Sandefjord, Norway |
| Posts: | 617 |
| Status: |
Offline
|
The oil pump is a positiv displacement device, so amount of oil going through the pump is simply proportional to engine revs. It can, however, only handle a certain amount of back pressure before destroying itself, that is why there is a pressure regulator bypass valve. Once that valve starts cracking open, oil flow diverts to the bypass from the engine - where it really is supposed to go. Since oil pressure has no effect on the lubrication of plain bearings - other than providing the driving force for moving oil to them, the conventional wisdom that high oil pressure is good is wrong.
The amount of oil moved by the pump is not related to oil viscosity, but the amount reaching the bearings definately is. Oil flow into the engine will not exceed the amount going into the engine at the RPM where the bypass valve cracking pressure is reached, thus we should choose the highest oil weight that causes the oil pressure regulator to kick in at around max RPMs, possibly just a bit earlier.
Time to dig out my books in fluid mechanics and oil hydraulics, haven't really thought of those subjects for 12 or 13 years.
--
Joachim