oil filter flow vs filtration

Gary Allan · Jun 1, 2005

quote:

I'm not trying to preach just teach.
Maybe this is where I'll get myself booted off this forum but here goes.

Okay ..now that we got that straight. I knew I was slow ...

We've been there and done that, Pete. Nothing your saying is news here.

If you would care to prepare a "oil pump relief and oil filter bypass primer for the unaware" ..then, please compose it and start your own topic with everyone's blessing. Be prepared for an intensive peer review. For a good many people here ..it ain't their first time to the rodeo.

and no one gets booted off of here for self glorification or apparent grandeur (delusional or otherwise). That's a right that will not be infringed upon. Just understand ..that you have to cash the checks that your ego is writing.

I would welcome your comments on the following topics:
Some suggested reading: Bob's test my works part II and part I

Razl · Jun 1, 2005

Gary,
Now I know why I always look forward to reading your posts

Sorry, I had nothing momentous to add to this thread

Gary Allan · Jun 1, 2005

quote:

The filter is a contributor to flow divergence(I do not like that term, but I know what you are saying)

Sorry. Can you recommend a one word term that will replace it that you would prefer?

quote:

Let me give my explanation. Like Pete says it is a hydraulics problem. The oil pressure relief opens because there is enough resistance downstream to cause the pressure to exceed the relief setting. The resistance that the relief valve sees is the sum of all the resistance components in the oil system(there are some parrallel paths so it is not straight addition). Those components include the roughness of the oil passages, the bearings, etc, and the oil filter.

Well, okay. No problem there. The parallel paths mean nothing to the pump, nor its pressure relief valve ..it doesn't know that they are there. It only sees pressure that is a result of its present flow through everything downstream. So far we're in total agreement.

quote:

So, yes, the resistance of the oil filter affects when the oil pump relief valve opens. Higher filter resistance would mean that the oil pump relief valve would be open more often.

Not so fast, Winston. Maybe Pete will give some normalized PSID specs for some typical NAPA Golds. Although the statement is true ..it doesn't necessarily have much weight in practice. As you've seen, the PSID for the dinky PureOne that I used had the same PSID stone cold ..or fully hot ..in every viscosity fluid there was. Surely the span of 5w-20 to 20w-50 would indicate if viscosity had any effect on PSID ..it didn't as long as the relief in the pump was closed. Nor to I believe that any filter would have much less PSID. That is, out of my potential 81.X lb limits ..the filter NEVER represented more then a static 3-4 PSID ..nothing compared the the resistance of the rest of the engine. That is, the filter resistance may be up or down 1 PSID when the filter is NEW ..but every filter at some point in it's use will gain resistance. So a "free flowing" filter ..will look just like an "extremely restrictive" filter at some point.

The only time this static PSID changed was when the pump was in relief. That's where the chicken and eggs thing occurs that I really want Pete to answer to a point where some lightbulb goes off. His superior in depth understanding of hydraulic theory should be able to easily explain such a routine event.

Your PSID is 3.5 ..but when the relief is open ..it jumps to around 10-12 ..but that's close to the bypass setting .. but the reason that the relief valve is open ..is becasue the engine can't accept anymore flow ..so how is more flow going to occur if the bypass is open?? As the relief valve closes ..the PSID normalizes ...

So even if you're at the apparent bypass setting ..is any oil going to bypass when the oil pump is in relief?

rg144 · Jun 1, 2005

I vote this as best thread of 2005.

There are some nice conclusions here.

Vis. is not an issue with filters - they are the least intrusive component of the hydraulic circuit and easily go to bypass to lay 'low' as it were. Their media should never rupture (barring failed bypass valve). But ...

The pump won't cause that to happen (assuming it has a relief valve). Also, engine manufactures specify a pump to assure that oil starvation to bearings, etc. will not occur, filter be ****ed. Therefore the media is out of the equation (except for brief moments where it is the guilty party activating the bypass).

[ June 01, 2005, 07:25 PM: Message edited by: rg144 ]

Winston · Jun 1, 2005

quote:

Although the statement is true

OK, so we agree.

quote:

..it doesn't necessarily have much weight in practice.

Now this is a whole different ball game. You go on to argue that the filters PSID does not vary, but your own tests show otherwise.

Then you go on to state that the PSID was NEVER greater than 3-4PSID. But wait, then you state the exception.

quote:

The only time this static PSID changed was when the pump was in relief

So the PSID does change.

quote:

Your PSID is 3.5 ..but when the relief is open ..it jumps to around 10-12

This is where you always loose me. You keep trying to say that the PSID for the filter is related goes up because the oil pump relief valve being opens. It does not work that way. The PSID across the filter is what it is. If the filter PSID is high, it will tend to make the oil pump relief open.

So lets back up. Your tests clearly show that during startup the PSID across the filter jumps up to 10-12psi. This is quite a bit of pressure drop. This makes the oil pump bypas open more. If the filter was less restrictive, the oil pump bypass would not open as often.

Gary Allan · Jun 1, 2005

Winston ..Winston ..enhance your calm (visions of Demolition Man)

quote:

Now this is a whole different ball game. You go on to argue that the filters PSID does not vary, but your own tests show otherwise.

No Winston, reveiw the text throughout any of my posts. The only time that I ever saw anything above 3-4 psid was when the pump was in relief. We've debated this at length in several threads.

quote:

So the PSID does change.

Yes, you have been paying attention

quote:

This is where you always loose me.

Apparently so.

quote:

ou keep trying to say that the PSID for the filter is related goes up because the oil pump relief valve being opens. It does not work that way.

I'm sorry, Winston ..but I can't wish this away. This is exactly how it worked. At no other time did I see anything other than normal PSID (3-4 psid). It only occured in those instances.

Don't blame me for the results. I'm merely the messenger. Do you think I'm trying to author my own radical flow theory to be published for SAE? I don't even have one bona fide physics course to my credit.

quote:

If the filter PSID is high, it will tend to make the oil pump relief open.

Well, if you're comparing a new filter with 3-4 PSID and a used one with 8 PSID ..then you may put the pump into relief if the conditions are right. You will be closer, in like situations, to it's threshold.

quote:

Your tests clearly show that during startup the PSID across the filter jumps up to 10-12psi.

No ...it shows that when pressures were @ 82 psi (one qualification) that the downstream pressure would be lower to the tune of 7-12 (12 having a *). There was no other time that such a differential was seen. That is, if the pump pressure was 81 or 80 ..the downstream pressure was 76-77 or 77-78 ..regardless of visc/temp/rpm/etc. NEVER AT ANY TIME THAT THE MAX SYSTEM PRESSURE WAS NOT REACHED (*) DID IT EVER SHOW INCREASED PSID

quote:

This makes the oil pump bypas open more. If the filter was less restrictive, the oil pump bypass would not open as often.

Now here's where we're in conflict here. You're answering a question that wasn't asked ..since it's based on a false assumption.

The high PSID is only apparent when the pump is in relief. It isn't the cause ..it's the result.

What happens when I started the engine in these situation is that both needles swept up at the same rate (very near) ..and the down stream one just hung up at a lower pressure. If the filter was a factor before that point, one would reason that there would be a larger differential as they swept upward.

So when the relief is close ..the flow could care less what's in its way. When the relief is open ..it now has competition for flow ..and shows this with increased PSID.

Winston, I can't effectively articulate what I'm conceptually seeing here. Here is a situation that isn't explained ..a least reasonably. It gets "canned answers" that are easily challenged (as you can see by our ongoing ramblings on this one little point

)

Perhaps Pete can help me out here and put my

to rest.

* exceptions: When 20w-50 weight oil was used in a very cold start, the relief pressure could not be seen at the gauges since the 3/8" lines became part of the "resistance package". Normally, with all other weights under all other conditions the lines had no impact on max pressure. Their resistance, @ 36", was probably measured in "inches of water column" ..or basically an non-factor. Pulling numbers out of my ***, it would appear as 75/60 in this instance ..where it should be 82/67.

On other odd event was that 5w-20 appeared to have a slightly elevated differential (no where near the bypass setting) for a very brief time. It was suggested that it may be due to a slightly imperfect relief seal.

Pete C. · Jun 1, 2005

quote:

Originally posted by Winston:
Pete,

Thanks for chiming in. As you point out flow on an engine oil pump is dependant on rpm. Since a typical engine varies from 750 to 6000 rpm, the flow rate will vary greatly. Is your example of 12.987 gpm at 3000rpm common?

Nah. It was just easier to calculate in my head. The dealer should be able to provide you with the displacement volume of any oil pump just do the math and then get throughly confused.

Pete C. · Jun 1, 2005

I'm off to check the bulk modulus and compressibality of my wiper fluid, (another hydraulic system) It's lunch time!!!!

Gary Allan · Jun 1, 2005

Pete ..you're preaching to the choir here (as well as a few elders). These topics have been explored ad nauseum and we're, as I said, moving beyond these basic tenets of flow and flow dynamics ..and into the subtle and curious apparent issues that upset our perceptions.

You're obviously well versed on this ..but so are others.

It's not that one dimensional outside the box.

If you insist, we can requalify ourselves to assure you that we have a grip on everything your stating. If your qualifying yourself ..you've done that with outstanding success.

[ June 01, 2005, 12:09 PM: Message edited by: Gary Allan ]

Gary Allan · Jun 1, 2005

quote:

I still maintain that if the pump relief valve is open, the filter restriction will affect the flow to the engine, but that is the only time the filter restriction will affect flow to the engine.

Perhaps, Winston. I don't think that I've ever disputed that assertion. What we don't know is how to necessarily interpret data when the relief is open in terms of PSID. Is the apparent resistance of a filter a contributor to flow divergence (it's not the cause) ..or is it a result of flow divergence?

Can you tell me which?

Pete will be back in a we'll have a good exchange going here in a 1/2 hour or so.

Winston · Jun 1, 2005

quote:

Winston ..Winston ..enhance your calm (visions of Demolition Man)

I accept that I am language challenged. I do much better with sketches and drawings. I have seen Demolition Man, but I do not understand this statement.(it sounds cool though - Enhance your calm.)

quote:
--------------------------------------------------------------------------------
Your tests clearly show that during startup the PSID across the filter jumps up to 10-12psi.
--------------------------------------------------------------------------------

No ...it shows that when pressures were @ 82 psi (one qualification) that the downstream pressure would be lower to the tune of 7-12 (12 having a *). There was no other time that such a differential was seen. That is, if the pump pressure was 81 or 80 ..the downstream pressure was 76-77 or 77-78 ..regardless of visc/temp/rpm/etc. NEVER AT ANY TIME THAT THE MAX SYSTEM PRESSURE WAS NOT REACHED (*) DID IT EVER SHOW INCREASED PSID

OK. Excuse my lack of html prowess.

Once again you are trying to link the the fact that the oil pump relief is open with the fact that the filter psid is high.

I will say it one more time. Your tests clearly show that during startup, the PSID across the filter jumps up to 10-12psi.

Don't give me this "yea, but but the oil pump relief was open so it does not count junk." THE PSID WAS 10-12PSI!!! End of story.

You also assume that the the pressure drop under certain circumstances is due to losses in the hose. However, just remember that is your ASSUMPTION. You do not know if it is true.

I've had a couple beers tonight, so I am a little more "open" than normal.

On a side note

From Rg

quote:

I vote this as best thread of 2005.

Wow! I am honored to be involved.

Pete C. · Jun 1, 2005

Good morning gentleman (?)

Lets get a few things straightened out...;

There is no such thing as STATIC PSID. Look up static in yer Dictionary.

Differential pressure is DP, not PSID.

None of the relief valves in an automotive oil circuit open fully during a "normal over pressure situation". They open just enough to alleviate the over pressure.

Same goes for the DP (bypass) valves in the filter. (no matter what type or who's valve).

Unless you are using a "dampened" type pressure gauge, the needle will move farther in either direction in response to a sudden increase/decrease in pressure, before settling on the actual pressure. As a general rule the middle of the scale reading on a guage face should be the middle of the expected pressure fluctuations.

As long as an oil pump is working correctly there will ALWAYS be a pressure drop across the filter element. The only time there is no drop is if there is no flow path downstream from the filter. In which case the pressures equalize, The relief valve opens and hopefully, the can doesn't burst and the bearings gaul.

quote:
--------------------------------------------------------------------------------
What we don't know is how to necessarily interpret data when the relief is open in terms of PSID. Is the apparent resistance of a filter a contributor to flow divergence (it's not the cause) ..or is it a result of flow divergence?

Rembering how and why a relief valve works, the pump ALWAYS wants to put out a specific volume of oil. It DOES NOT CARE where that volume goes. (FYI the actual oil pump is upstream from the relief valve) The oil will move through both the relief circuit and out to the engine when the relief is activated. The volume of oil going through the filter will be a reduced amount that depends on how much is flowing through the relief circuit. BUT it is still flowing to the engine. As to how much is flowing... That depends on pump volume and the amount flowing through the relief circuit to alleviate the reason the relief opened in the first place.

So unless the outlet port on your oil pump is totally blocked. Your filter is so clogged and has no bypass. And your engine is running there will always be flow to your engine.

I think this is Garys statement:
"What happens when I started the engine in these situation is that both needles swept up at the same rate (very near) ..and the down stream one just hung up at a lower pressure. If the filter was a factor before that point, one would reason that there would be a larger differential as they swept upward.

Sorry Gary but your wrong on this one. the DP is what it is. The differential between the pump side of the resistance to oil flow and the pressure on the other side of that resistance.

If it takes 10 psi to START and MAINTAIN a given flow of any medium through any resistance that is the DP that will always be the constant. No matter wheather the system pressure is 50 psi or 2000 psi. the DP will always be 10 psi at that flow rate. Increase the flow rate through the same resistance and the DP goes up, Not the system pressure.

Dang this is hard on the brain this early in the AM.

[ June 02, 2005, 08:04 AM: Message edited by: Pete C. ]

Filter guy · Jun 1, 2005

Pete C..thanx for clarifying the "higher" flow rates found in todays engines as i had mentioned earlier.

As we know, the oil is recirculating and won't pump out on 5 seconds..unless theres a hole in the block...lol
--------------------

Was wondering do you concur that a new element, on average, has about a 1 PSI pressure drop?

Do you also concur that used elements when returned rarely are plugged. That , again on average, there is better than 50% of the life left. Obviously there are exceptions based on sludgy or contaminated oil and other problems.
But if joe consumer is doing a decent job of folowing the OEM's recommended oil change intervals, that there usually is plenty of life left in the filter.

And with that in mind and Gary's 3-4PSID filter, this would be typical of a used filter that has plenty of life left.

Pete C. · Jun 1, 2005

quote:

Originally posted by Filter guy:
Pete C..thanx for clarifying the "higher" flow rates found in todays engines as i had mentioned earlier.

As we know, the oil is recirculating and won't pump out on 5 seconds..unless theres a hole in the block...lol
--------------------

Was wondering do you concur that a new element, on average, has about a 1 PSI pressure drop?

Do you also concur that used elements when returned rarely are plugged. That , again on average, there is better than 50% of the life left. Obviously there are exceptions based on sludgy or contaminated oil and other problems.
But if joe consumer is doing a decent job of folowing the OEM's recommended oil change intervals, that there usually is plenty of life left in the filter.

And with that in mind and Gary's 3-4PSID filter, this would be typical of a used filter that has plenty of life left.

Just got off the phone with the test lab folks and they say that a typical DP on a light duty Ford (51515)type filter there is about a 1.8 psi drop @ 3gpm @ 180deg. These are Fords test specs. and are pretty typical for the other filters.

They don't do any checking for "remaining life" on returned filters since it's a subjective issue and not part of the warranty process.

Hope this helps.

Brian Barnhart · Jun 1, 2005

quote:

Pete C..thanx for clarifying the "higher" flow rates found in todays engines as i had mentioned earlier.

Re-read the posts FG. He didn’t confirm the numbers. In fact he gave some much lower operating numbers in his post just above.

quote:

As we know, the oil is recirculating and won't pump out on 5 seconds..unless theres a hole in the block...lol

Four quarts won’t run out of an oil pan in 5 seconds even if the drain plug is removed, so I doubt it would drain down from the upper parts of the engine in 5 seconds. Assuming all the passages are filled, just where, in an engine, can 4 quarts go in 5 seconds? About the only need I see for 12-15 GPM flow from an oil pump would be to quickly fill engine oil passages or an empty oil filter and during/after starting.

Modern oil pumps may have a 12-15 GPM flow capacity at high RPM, but I doubt a healthy engine’s internals will allow that level of continuous flow within the pressures allowed. Assuming the pump is capable of 12-15 GPM, I suspect that pump would be bypassing quit a bit at high RPM, even on a hot engine.

So, even if the pump is rated at 12-15 GPM, the filter doesn’t necessarily need to be rated to flow that much at a low pressure drop since once the engine’s oil passages are full, the engine’s resistance will reduce the flow to a level much less than 12-15 GPM due to the constraints of the system operating pressures (oil pump bypass pressure).

What we need is some input from a real engine oil pump designer.

Pete C. · Jun 1, 2005

Once again...
automobile engine oil pumps are fixed displacement pumps. they are designed to put out a FIXED volume of oil per 1(one) revolution. I used 1 cubic inch as an example (re-read the post guys) the TOTAL output per minute, be it gallons per minute, liters per minute, CC's per minute or cubic miles per minute, is dependent on how many times you turn the input shaft per minute multiplied by the fixed displacement of the pump. More RPM's more VOLUME, Fewer RPM's less volume.

Quote:
"Re-read the posts FG. He didn’t confirm the numbers. In fact he gave some much lower operating numbers in his post just above."

Nowhere in the referenced post did I say that. Those are numbers (Ford specs, flow rate and oil temp.) that we use to test filters. not the flows and pressures found in an engine.

Oil filters are designed to flow MORE than the normally expected flows in an oil system, not less.

PLEASE!!! DOES ANYONE KNOW THE REAL DISPLACEMENT OF A FORD 5.0 LITER OIL PUMP??????? OR A MOPAR 5.2LITER ??? GM 5.8 LITER ???

Gary Allan · Jun 1, 2005

quote:

There is no such thing as STATIC PSID. Look up static in yer Dictionary.

Well, since you take exception to my nomenclature in this situation ..I'll forever go to the trouble to state it as "typical" or common ..or "normally". Yes, it was a dynamic situation ..but otherwise a psuedo "baseline" (yes, when the engine was running)

Please ..use something other than semantics here in discounting others assertions

quote:

Differential pressure is DP, not PSID.

Tell that to the people who manufacture differential pressure gauges. They need your help in this matter.

0-1 PSID Differential/Gage 287-1002-ND 50.09 35.91 28.47 ASCX01DN
0-5 PSID Differential/Gage 287-1003-ND 50.09 35.91 28.47 ASCX05DN
0-15 PSIA Absolute 287-1008-ND 50.09 35.91 28.47 ASCX15AN
0-15 PSID Differential/Gage 287-1009-ND 50.09 35.91 28.47 ASCX15DN
1
0-30 PSIA Absolute
0.25 ~ 4.5V SIP 4.5 ~ 16 100µSec -25°C ~ 105°C
287-1010-ND 50.09 35.91 28.47 ASCX30AN
0-30 PSID Differential/Gage 287-1011-ND 50.09 35.91 28.47 ASCX30DN
0-100 PSIA Absolute 287-1004-ND 50.09 35.91 28.47 ASCX100AN
0-100 PSID Differential/Gage 287-1005-ND 50.09 35.91 28.47 ASCX100DN
0-150 PSIA Absolute 287-1006-ND 50.09 35.91 28.47 ASCX150AN
0-150 PSID Differential/Gage

However ..many do also use the notation DP.

Your point beyond giving needlessly discounting text that has no more merit than mine??

quote:

As long as an oil pump is working correctly there will ALWAYS be a pressure drop across the filter element. The only time there is no drop is if there is no flow path downstream from the filter. In which case the pressures equalize, The relief valve opens and hopefully, the can doesn't burst and the bearings gaul

Sure ..has anyone disputed this?

quote:

Rembering how and why a relief valve works, the pump ALWAYS wants to put out a specific volume of oil. It DOES NOT CARE where that volume goes. (FYI the actual oil pump is upstream from the relief valve) The oil will move through both the relief circuit and out to the engine when the relief is activated. The volume of oil going through the filter will be a reduced amount that depends on how much is flowing through the relief circuit. BUT it is still flowing to the engine. As to how much is flowing... That depends on pump volume and the amount flowing through the relief circuit to alleviate the reason the relief opened in the first place.

So far ..I don't have any coflict with this

quote:

So unless the outlet port on your oil pump is totally blocked. Your filter is so clogged and has no bypass. And your engine is running there will always be flow to your engine.

Yep, unless you've got a fluid that has no pumpability ..I'll join in with an arm raised and a cheer...

quote:

I think this is Garys statement:
"What happens when I started the engine in these situation is that both needles swept up at the same rate (very near) ..and the down stream one just hung up at a lower pressure. If the filter was a factor before that point, one would reason that there would be a larger differential as they swept upward.

Sorry Gary but your wrong on this one. the DP is what it is. The differential between the pump side of the resistance to oil flow and the pressure on the other side of that resistance.

Now is where you run out of steam in effectively explaining the events.

The canned answer is "the DP is what it is" is not good enough. Sure the statement is obviously ..obvious ..but no detailed reasoning is behind it.

Take this event and explain it:

In all instances that the pump is in relief (evidenced by the max oil pressure being reached at idle where other situations with warmer starts or lower visc oil do not reach that max pressure (82 psi)) that this is the only time that higher differential is noted. Otherwise ...it's a normal 3-4 PSID (or DP as you seem to prefer)

How is this possible, Pete? How does a filter have a variable resistance? It doesn't ..or can't. It doesn't change between one event and the other. It is only the distinciton of having the pump in relief that accompanies this event.

So far you've given canned anwers and haven't explained this.

Why do I see up to 12 PSID when the relief is open ..but NEVER anything above the normal 3-4 when it is closed?

This is a function of the difference of, in the view of the PSID across the media, a series fluid circuit and one where the filter/engine is a subcomponent of a parallel circuit.

You're still not far enough below the surface on this here.

This is what occured ..this is the data. As flawed and sophmoric the test conditions may be, there is a decent margin of validity to my observations that doesn't require a Phd or an engineering degree to reason through ...or at least observe.

If we take your current ponderings on this ..BOTH of my observations are both correct and impossible. The 3-4 DP

is valid ..and the 7-12 DP is also valid. Yet they have no reason to change ..but they did ......................

.......and only when the relief at the pump was open.

Got anything more than dicounting rhetoric??

Again, I'm not publishing a paper ..I'm just the messenger. It's your job, should you decide to take it, to explain this stuff. These are not questions of how a pump works ..nor a bypass valve. These are questions of reactive "apparent" conditions that are altered by the mode they are in. One is a series fluid circuit of vaiable flow through a, somewhat, fixed conduit. In that mode ..the filter represents a very minor pressure drop in the total circuit with the engine. When flow is split ..this resistance has more apparent resistance ...since the circuit is no longer a series circuit.

It's a matter of defining this apparent difference that is the whole origin of this ongoing debate.

[ June 02, 2005, 11:03 AM: Message edited by: Gary Allan ]

Winston · Jun 1, 2005

Once again I did not write fast enough and Gary got in ahead of me. Funny how we pounded on the same points.(edit)

quote:

Differential pressure is DP, not PSID.

DP is an abbreviation for Differential Pressure.

PSID is a term used for the units when measuring differential pressure.

Differential pressure gauges usually have PSID stamped on the gauge face so that people reading the gauge know that it is a differential pressure gauge. (check with your lab folks) The use of the term PSID in these posts is completely acceptable.

http://www.bucksales.com/Principals/DifferentialGauges/differential_pressure_gauges.htm

quote:

Unless you are using a "dampened" type pressure gauge, the needle will move farther in either direction in response to a sudden increase/decrease in pressure, before settling on the actual pressure.

This is irrelevant, the pressures in an engine don't change rapidly enough to cause a gauge to overshoot the reading. Plus if the gauge did overshoot a reading it would only be for a fraction of a second.

quote:

So unless the outlet port on your oil pump is totally blocked. Your filter is so clogged and has no bypass. And your engine is running there will always be flow to your engine.

I think we all agree that there is always flow to the engine. The point is how much flow to the engine.

quote:

As to how much is flowing... That depends on pump volume and the amount flowing through the relief circuit to alleviate the reason the relief opened in the first place.

What I am trying to say is that the filter is one of the components in the circuit contributing to the need to open the relief valve to the relief circuit.

By the way, thanks for the data on filter flow at 180degF for the Ford application. What would REALLY help us out is if you could give us the following data for the Ford application.

psi drop through the filter @3gpm with 40deg conventional 5w30 oil with your synthetic media.

psi drop through the filter @3gpm with 40deg conventional 5w30 oil with your plain paper media.

[ June 02, 2005, 10:55 AM: Message edited by: Winston ]

Brian Barnhart · Jun 1, 2005

quote:

PLEASE!!! DOES ANYONE KNOW THE REAL DISPLACEMENT OF A FORD 5.0 LITER OIL PUMP??????? OR A MOPAR 5.2LITER ??? GM 5.8 LITER ???

Knowing the displacement will give you theoretical flow at a given RPM for an ideal PD pump, but that’s not all that’s required to know flow through an engine. Pump tolerances, engine design and the pump bypass pressure setting will affect how much actual flow goes through the filter and into the engine, versus what is bypassing.

I suspect the Ford test spec numbers you posted are not far from a typical operating condition on a real engine.

Winston · Jun 1, 2005

quote:

In all instances that the pump is in relief (evidenced by the max oil pressure being reached at idle where other situations with warmer starts or lower visc oil do not reach that max pressure (82 psi)) that this is the only time that higher differential is noted. Otherwise ...it's a normal 3-4 PSID (or DP as you seem to prefer)

Just because two events happen at the same time does not necessarily mean that they are related.

quote:

How is this possible, Pete? How does a filter have a variable resistance? It doesn't ..or can't. It doesn't change between one event and the other. It is only the distinciton of having the pump in relief that accompanies this event.

The filter does not have variable resistance. The resistance (DP or PSID) varies based on flow and fluid viscosity. One more thing the resistance across the filter must change as you rev the engine. If you do not see a change it is because your gauges are not accurate enough. Which is very possible since you do not have a differential pressure gauge. You are onle reading the difference between the two gauges.

By the way. Is your guinea pig repaired?

oil filter flow vs filtration

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