I've only responded to the first of your three latest posts ... dude, you're goin' nuts here.
If I find time, I'll address some of your last two posts. This is getting really time consuming, and frankly my time could be spent on better things.
Originally Posted By: Gary Allan
Quote:
How can “the throughput of the oil biases more to the engine” happen if the SAME FLOW is always going through both the filter and engine in the series flow path?
Dood. You've got 100% flow out of a pump. A percentage of that ISN'T GOING THROUGH THE FILTER OR ENGINE.
IT EXISTS, AT WHATEVER FLOW RATE THAT IS, AT OR ABOVE THE RELIEF LIMIT (AT the limit so that this "MAY" get through to you).
Yeah, so? ... I’ve said that many times in this thread. Everything that comes out of the pump either goes through the filter/engine circuit OR is split between the filter/engine circuit and the relief valve that spits flow back to the sump. No news here.
Originally Posted By: Gary Allan
Let's say that 50% of the 100% is shunted/relieved (for example)
That means that 80% of the flow is going through the filter and the engine.
Whoa ... if 50% of the 100% pump volume output is shunted/relieved, then 50% of the flow is going to through the filter and the engine – NOT 80%. Probably a typo – no one is that bad at math.
Originally Posted By: Gary Allan
So, 50% of the flow with 100% of the pressure applied. What pressure is the engine going to see?
A:50% of what it would if it was receiving 100% of the flow. No denying that ...DOOD.
Not necessarily true. The pressure the engine is going to see will be equal to 85 psi (supply pressure in relief mode) minus whatever the filter PSID will be with this 50% flow volume flowing through it. Again, the PSID across any flow device (restriction) will be determined by the flow volume, oil viscosity and flow resistance of the device. In any pump relief mode case (at any given point in time - meaning all conditions being constant), the flow volume going to the filter/engine is the max possible since the pump is holding the supply pressure at a constant 85 psi – more on that later.
So the actual pressure the engine sees in this case will be totally dependant on what filter PSID is generated by this “50% flow” volume. The only way the filter/engine could receive 100% of the pump flow would be if the pump was out of relief mode just below the relief pressure (ie, 84.9999 psi). The filter/engine can also receive 100% of the pump flow if the supply pressure is well below relief pressure ... BUT, in order for that to happen it would mean that the pump RPM was less, which produces less volume and a pressure below the relief valve setting.
The bottom line is that the pump can not push any more volume through the filter/engine circuit than the 85 psi will allow. Any excess volume beyond that will go out the relief valve and back to the sump. As always, assume viscosity is constant in these examples.
On a side note ... the actual relationship between pressure and fluid flow volume rate through a fixed resistance is not a linear function ... but for simplicity sake we can assume that it is in your example. Flow volume rate is actually proportional to the square root of pressure. Guess who says so – your buddy, Bernoulli.
Originally Posted By: Gary Allan
So, if you take our 85lb max ..and take 50% of that, we would have 42.5 across the engine ..and 42.5 across the filter.
The engine could only see 50% of the 85 psi pressure IF the filter had exactly the same resistance to flow as the engine did, and caused half of the 85 psi supply pressure to drop across the filter (a 42.5 PSID). That’s not the case ... do you really think a filter will have the same flow resistance as the engine. Remember your 2 ft dia pipe vs. 1/2 “ dia pipe analogy? You’ve said may times that the engine is magnitudes more restrictive than the filter ... so why are you now saying they are the same.
That PSID breakdown is NOT possible unless the filter was just as resistive to flow as the engine was in this serial flow circuit.
The filter will have a PSID across it that is totally dependant on flow volume, oil viscosity and filter resistance – call it a realistic 5 psi pressure drop in this case since we both know a filter is MUCH less restrictive than the engine. That means in this case that the engine’s inlet pressure (ie, oil pressure gauge) would be reading 80 psi (85 psi – 5 psi).
The amount of pressure drop across the filter and engine will always be split in proportion to the resistance ratio of each in the flow circuit – the sum will always add up to the supply pressure (of course). Also (and this is KEY), the amount of volume that the pump sends to the filter/engine circuit while in relief mode is also dependant on the oil viscosity and filter/engine flow path resistance. The engine’s resistance is fixed, so if you put in a more restrictive filter on the car, then there will be less volume going to the filter/engine while in pump relief mode - 85 psi supply will push less volume as the flow path resistance goes up, and the rest of the pump volume output goes back to the sump.
This is exactly why some guys see a lower oil pressure when using a more restrictive oil filter. Of course, cold start/run scenarios is where this will show up the most.
Originally Posted By: Gary Allan
BUT WAIT, we have a filter bypass that doesn't allow this to occur. It's maxed @ 23lb..so the engine MUST SEE
85-23=62
regardless of what the filter would offer in resistance if no bypass valve existed.
That's why it is there.
Yeah, I agree that the filter’s bypass valve will indeed limit the filter’s max PSID, and in turn “ensure” enough oil volume gets to the engine. That maybe one aspect of its function, but I really do not think the main purpose of the filter bypass valve is there to regulate how much oil pressure/flow the engine sees. The filter bypass valve setting is really there to ensure that the filter will only go into bypass mode when it’s supposed to. If the bypass setting is set TOO LOW for a particular application, then it will be bypassing unfiltered oil much too often and longer as compared to a filter with the right bypass setting. The “ultimate goal” IMO, is to have an oil filter that never goes into bypass mode unless it’s getting too loaded up with contaminates to the point where the filter is choking engine pressure to the danger point, or the filter element can’t take the PSID (which ever occurs first).
Originally Posted By: Gary Allan
As the flow is more and more biased to the filter/engine, that pressure differential MUST retreat.
Major error here. There is no such thing as ... “the flow is more and more biased to the filter/engine” resulting in a “retreat” (decrease) in the pressure differential between the filter and engine. That is what you mean, I assume?
That is because when the oil pump is in relief mode - and assuming the relief valve works perfectly to keep the supply pressure right at 85 psi – then the flow volume going to the filter/engine is going to be constant (with constant oil viscosity). I tried to point this out earlier, but you don’t seem to read/comprehend my stuff. Any time the oil pump is in relief mode the oil volume going to the filter/engine is constant, and will be the max possible for the system conditions at that exact point in time. As the pump goes out of relief mode - which can only happen if the engine RPM has decreased if all conditions are constant – then the pump output volume to decrease as well, and less volume will be going to the filter/engine.
When the pump hits the relief pressure, the flow to the filter/engine stays at a max constant while the flow going back into the pump increases as the pump’s output increases with the supply pressure at 85 psi.
Gary Allan said:
If you can't admit that MORE FLOW through the engine will drop more pressure ..then you've just spit in Ballony's eye.
The only thing that is pure B-O-L-O-N-E-Y around here is some of your thoughts on how an oiling system like this really works – and also your writing skills at times..