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On 5 May 2001, at 20:54, Keith Park wrote: > I talked to one of the engineers at work that knows fluid stuff and he > said that putting an obstruction in line with the oil passage such as > the oil filter is will reduce pressure at the output side, and when > dealing with an oil pump that is not able to keep up at idle can > greatly reduce the idle pressure while with extra capacity at > operating speeds will work fine. I suppose he's right in that this is another example of something that requires compromises, but I still think they compromises are worthy ones. I have driven several engines with more than 100kmiles on a full flow system, all with no problems. It is important to understand exactly what the pressure we measure means. This is NOT the pressure that will be present in the bearing that keeps the metal parts from touching each other. The hydrodynamic pressure in the bearing is MUCH higher and is actually generated IN the bearing BY the bearing in exactly the place where it is needed. The pressure we measure is just a measure of the amount of flow we are getting to the bearing and is an indicator of the condition of the pump, and the flow resistance between the gauge point and the sump (thru the passages and the bearings.) It's really all too easy to get bent out of shape worrying about having enough pressure, when all you really want to know is whether there is enough FLOW to the bearing. Of course you also need good bearing clearances in order for the journal bearing dynamics to work. - ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ------------------------------------------------------------------- List info at http://www.vwtype3.org/list or mailto:help@vwtype3.org