Agreed. The PD pump will move the amount of oil through the gears based on RPM regardless of ... anything, including the oil filter behavior. But "Anything" includes the pump bypass relief valves, which can open, in which case the oil does not go through the engine.This is not correct - the oil filter is just a small "resistor" in the oiling system. The PD oil pump doesn't care is there if there's a bypass valve in the oil filter or not ... it makes no difference to the PD pump.
Forgive my not being certain of terminology, but I assume that "gallery" means the engine? Not if something is stopping it from flowing that way - If something is stopping it, then the pressure will rise to open the pump first stage relief valve and eventually the full pump bypass relief valves, and the PD pump will be happy because it will be moving the oil that it must to rotate, just not through the engine. THIS is the sticking point: Does the WIX specification that says that the maximum flow is 8-10 GPM mean that due to the physics of oil fluid flow through the media mean that the pressure required rises very quickly and no-way can you force more than 8-10 GPM through the filter media? This would mean that the pump pressure relief values will open and the excess flow will simply bypass the filter AND engine. OR, does it mean that this is the design limit for the filter due to many unspecified factors such as rupture of the media, bending of the media support, failure of the media anchoring at the ends, etc. Hardly a good situation either. Either way WIX is saying that the 57055 is not suitable for an application which requires more than 8-10 GPM to flow, certainly not an FB25 whose PD pump HAS to move 58.1 qt (14.5 gallons) of oil per minute at 6000 RPM. UNLESS the failure mode is that the 57055 flow is limited as opposed to that the 57055 tears itself apart, AND it is OK if the engine only gets 40 quarts , which violates the understanding that oil flow is proportional to RPM (Unless the pump is pumping at least 40% more than is needed at low RPM).There will be a max pressure and volume flowing in the gallery before the oil filter when the oil pump is in pressure relief.
IF the filter will allow that volume to flow through it. But see above: WIX states "Max Flow Rate 8-10 GPM". I take this to mean that manufacturing variations result in the Max Flow Rate limit varying from filter to filter to be between 8 and 10 GPM. An FP25 would pump 10 GPM at (40/58.1)*6000 = 4100 RPM, and 8 GPM (Presumably a rate that their design is certain to support) at 3300 RPM. Have you ever exceeded 3300 RPM? I have, likely every time I go out. 4100 RPM? I have too. I have even exceeded 3300 RPM for an extended period of time! Either (1) The filter will not allow this flow rate and the flow rate will be forced to be lower, the pressure will rise, and the pump bypass relief valve will open at 21 PSI and a little higher the filter bypass valve will open at 23 (or 27) PSI, or the filter will mechanically fail (tear apart). I think the likely result is that the bypass valves will open, the engine will get less oil, and the oil it gets will be dirty. According to the WIX specifications for the 57055, that filter is simply not suitable for use on an FB25 if the engine is run over 3300 RPM. (To be clear, I am hoping that someone will point out a flaw in my reasoning, not that I will succeed in shooting down WIX).That volume will go through the filter and into the oiling system.
Clearly.The bypass valve on the filter only operates from the delta-p across the filter.
Yes, but it will not all be filtered, some fraction of it will be dirty, very dirty. Which IS better than no oil at all, but certainly not a desirable situation.So if that volume going into the filter (along with the viscosity of the oil factor) causes the filter to bypass, that same total volume will still be going through the filter.
Oops, yes, sort of like a bypass oil filter, except that the bypassing oil is washing over all of the stuff that the filter has previously filtered out, washing it back into the engine, where as with a bypass oil filter the flow is split upstream of the filter so that the oil that bypasses goes out no dirtier than it came in. You might as well have no filter at all if this happens frequently.Only some will be bypassing the media.
Yes, and it opens about 2 PSI earlier than the Subaru filter, 6 PSI sooner than the WIX filter, stealing some of that Positive Displacement flow such that the engine does not get a flow of oil that is proportional to the RPM. Was it overkill so that this is OK? Or is it important at high RPM to have that much oil?The PD oil pump's pressure relief valve operates separately and disconnected from the bypass valve in the oil filter.