Subaru Oil Pump Specs as Relates to Filter Bypass

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Okay, to clear up any questions as to the oil pump specs I posted here is the service manual excerp:

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WagonBoss, good info from Hastings there. I'm now resigned to using the blue OE Subaru filter, though. This discussion has moved me to that conclusion, and that is a good thing in the end, even if I'm not a huge fan of Honeywell (FRAM) filter materials and design it is the factory authorized part and apparently these blue ones are the ones going on Subaru's leaving the assembly plant in Lafayette, Indiana (accross the river from my Alma Mater-- Go Purdue!). Also,in the rare event something comes up with my motor, being under warranty, Subaru can't balk on a claim over anything to do with the oil filter if its an OE (provided I can prove adherance to the maintenance schedule in the manual).
 
With the WIX filter having an 8-11 GPM max flow rate, wouldn't the filter have to be in bypass at high rpms? Even with 0/20 @ 180 oil temp ( Motul 300v 0/20 ) I still see almost 75-80 psi at almost anything above idle. Fwiw, my redline is in excess of 8K rpm on 91 octane, and I deal with cars that exceed 9K rpm on race fuel. It would be frightening to think that everything is going past the media. ( I typically use nothing but oversized WIX and Amsoil filters )

For some reason, I see Subarus flow rates being a typo or mistake ( Wishfull thinking maybe? ). I am looking through my WRX factory manuals, but cannot find the info.

Being a Subaru specialist, I have bumped into mistakes with Subaru info many times in the past.


Looks like I may have to look into a remote filter mount, with a pair of filters in parallel. It would at least give me a chance to use VERY large filters.
 
Originally Posted By: LoneRanger
WagonBoss, good info from Hastings there. I'm now resigned to using the blue OE Subaru filter, though. This discussion has moved me to that conclusion, and that is a good thing in the end, even if I'm not a huge fan of Honeywell (FRAM) filter materials and design it is the factory authorized part and apparently these blue ones are the ones going on Subaru's leaving the assembly plant in Lafayette, Indiana (accross the river from my Alma Mater-- Go Purdue!). Also,in the rare event something comes up with my motor, being under warranty, Subaru can't balk on a claim over anything to do with the oil filter if its an OE (provided I can prove adherance to the maintenance schedule in the manual).



The Purolator for the Subaru, ( the 14460 ) has a 20-25 psi bypass.
 
Quote:
That statement is way too general, or just plain wrong.


Well, it is a general statement. As it stands it is 100% correct. There is no functional way that a filter can produce flow or inhibit flow by itself. It requires some alteration of the pump.

..btw- I'll see if Lone Ranger has a schematic of where the tap is for the pressure reading. If it's downstream of the filter, then the pump will see 60 psi @ the 12.4gpm @ 17xF at whatever visc it's spec'd at. It will elevate the pressure as seen by the pump. I suspect that it is.

Quote:
In actuality, the flow volume THROUGH THE SYSTEM (which includes the filter) is a function of the pump's supply pressure AND the flow circuit resistance


Well, in actuality ..it's far easier to figure that the pump will have variable pressure, at a given IMMUTABLE VOLUME, through a given restriction.

Here's Bernelli for you, yo!

Quote:
Yeah, the pump's output performance has a bearing on the system flow, but so does the flow circuit's resistance which includes the filter (PSID). IF a filter is indeed was very restrictive, then it WILL effect the flow volume going through the engine - especially if the oil is cold or is very high volume.


That statement is way too general and just plain wrong. The pump, in the vacuum in the absence of senseless qualification that you seem to insist that I waste time on ..but are too lazy to do yourself, could care less whether it sees cold glue. Our theoretical pump has no boundaries unless they're qualified. Did Bernelli only exist in the mundane of what he could practically do??

For some reason you seem to grasp and lose this concept depending on which post you're typing.
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Quote:
You have to look at the entire SYSTEM to see what's going on.


I'm afraid that you don't. I don't have to know internal pump head or anything that you insist is essential to know/see the effects upon the filter. You seem to be unable to divorce Bernelli from the undeniable physical events and give them powers that aren't essential to understanding what occurs (more often then not).

Quote:
If you have a constant pump supply pressure, then the oil flow will choke down more and more through the circuit as the restriction to flow increases.


Again, in your unqualified statement, that's just plain wrong. Double the oil gallery and all passages in the engine and run the pump at the same rate ..the same volume will be flowing. The pressure developed will be less (assume for the sake of discussion that the pump is of 100% efficiency and that the pump is operated at some rational flow rate to avoid marginal/exceptional influences - how's that for qualification).

This is one concept that you have 100% inability to grasp. You keep going back to a faucet.

Quote:
The ONLY way a filter will NOT affect the oil flow going through an engine is if it has zero flow PSID (impossible) or the bypass is set to zero (doubt it).


So, now you're implying that if Subaru eliminated the filter ..that the 12.4gpm figure would be more (under the same qualified conditions that I described)??
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NOW we're really getting somewhere here.
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Originally Posted By: Gary Allan

..btw- I'll see if Lone Ranger has a schematic of where the tap is for the pressure reading. If it's downstream of the filter, then the pump will see 60 psi @ the 12.4gpm @ 17xF at whatever visc it's spec'd at. It will elevate the pressure as seen by the pump. I suspect that it is.


I should have a schematic or exploded parts view, as I grabbed all the pages for the engine portion of the manual. Long day today at work coming up, but later this evening I will look and post what I find.
 
Great! I know you've been hijacked here ..
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Now ..back to the slugfest.
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At loggerheads: Idiom Definitions for 'At loggerheads'
If people are at loggerheads, they are arguing and can't agree on anything.
 
I've been reading this thread with interest since I drive a 2005 Subaru with the Turbo engine. I think that their is a durability issue related to the high volume/pressure lubrication system and a high incidence of turbocharger failures, and found the response from the oil filter Mfg (Hastings) especially interesting.
In certain models (2005 is one of them) the oil line carrying filtered oil from the right side cylinder head to the Turbo has fine mesh sreen filter located in a banjo fitting at the exit from the head. On some engines this screen has become blocked with debris resulting in broken shaft in the Turbocharger. It's a chore to remove the screen to check/clean it, and it's not called for in any of the factory prescribed maintenance.
Since the their is only filtered oil going in to the line, I have wondered where the deris would come from in amounts large enough to block the screen completely. Now I think I see a cause for it. If aftermarket filters are run with bypass valves designed to open at 11 psi or even less, I can see that they could be running in bypass mode for a long enough time that it could cause the probem.
Some people have checked the screen condition after 60,000 miles and found nothing in it, while others suffer oil starvation turbo failures at 30,000 miles. I haven't seen anybody blame aftermarket filters yet, but I think it's a real possibility.
 
Originally Posted By: deeter16317
Couple points...

At almost 50 quarts of oil per minute, would you not expect the pump to literally suck the sump empty?? Sorry, but the oil doesn't return to the sump that fast in the real world as it gets hung up on things...

And do you REALLY think you are using almost 50 quarts per minute?? Think about the clearances...while the pump might be able to flow that much oil, its doubtful the engine (even in a completely worn out scenario) would flow that much oil...

If the clearances actually allowed that much flow, the engine would starve of oil at an idle...



Originally Posted By: Thingfish
With the WIX filter having an 8-11 GPM max flow rate, wouldn't the filter have to be in bypass at high rpms? Even with 0/20 @ 180 oil temp ( Motul 300v 0/20 ) I still see almost 75-80 psi at almost anything above idle. Fwiw, my redline is in excess of 8K rpm on 91 octane, and I deal with cars that exceed 9K rpm on race fuel. It would be frightening to think that everything is going past the media. ( I typically use nothing but oversized WIX and Amsoil filters )

For some reason, I see Subarus flow rates being a typo or mistake ( Wishfull thinking maybe? ). I am looking through my WRX factory manuals, but cannot find the info.

Being a Subaru specialist, I have bumped into mistakes with Subaru info many times in the past.


I agree that it seems like a HUGE (and unbelievable) amount of oil volume output from the oil pump. It very well could be a typo, but who can prove it? I don’t think my garden hose even flows at 12 gpm.
 
Welcome to the discuss, Paul B.

Gary: I don't consider the discussion to be a thread hijack at all, it has been informative... well as informative as it can be for me since trying to wrap my brain around some of the concepts you and Superbusa are discussing can be challenging at times as I have no training in fluid dynamics or fluid mechanics.

Now, to find that schematic for the oil pressure sender...
 
Originally Posted By: Gary Allan
Great! I know you've been hijacked here ..
21.gif


Now ..back to the slugfest.
grin2.gif



At loggerheads: Idiom Definitions for 'At loggerheads'
If people are at loggerheads, they are arguing and can't agree on anything.


I've concluded that these discussions are nothing but a frickin game for you. Everything I say, which by the way is usually correct, you find some way to twist it up in your head just to stir up sh*t. I could try to explain this stuff until I'm blue in the face and you would never admit that you're thinking is messed up on some of this stuff.

If you don't think an oil filter can contribute to flow restriction in the oil system, then go chew on this info for awhile. You like real test data ... right? Well, here ya go. As you can see (if you can read), is that each of those filters tested produced a different PSID across them with the same oil at the same flowrate. The PSID ranged from 6 to 16 psi dependant on the filter, with only flowing about 1.3 gpm of 10 deg C 10w-30 oil through them (relatively thick oil). I'm sure you'll twist something up to make it look like it was all done wrong, or the data is all bogus.
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http://www.geocities.com/rfpxj/Oil_Filter_Experiment.pdf
 
I think that spec is with no head on the pump. The pumps are positive displacement only in theory. They have clearances, as the pressure goes up the efficiency goes down.

FWIW, my WRX read ~100 psi cold, a common reading seen by those with gauges. This is above the 85 psi relief setting specified for the pump. Mine was reading at the top, back of the block in the main galley. This was essentially the greatest distance possible from the pump(lower front of engine). There is obviously a restriction to flow in the system.

Ed

Ed
 
Originally Posted By: edhackett
I think that spec is with no head on the pump. The pumps are positive displacement only in theory. They have clearances, as the pressure goes up the efficiency goes down.


That pump flow spec is with some kind of resistance on the output, otherwise the spec wouldn't specify it was at 43 psi discharge pressure. The 43 psi can't be a dead head output pressure, as it would certainly produce much more that 43 psi.

I have not seen any actual flow graphs of positive displacement pumps, and I'm sure there is some inefficiency on the top end, but if the pump is in good shape (ie, tight clearances) then IMO it's not going to lose much performance on the top end.

Originally Posted By: edhackett
FWIW, my WRX read ~100 psi cold, a common reading seen by those with gauges. This is above the 85 psi relief setting specified for the pump. Mine was reading at the top, back of the block in the main galley. This was essentially the greatest distance possible from the pump(lower front of engine). There is obviously a restriction to flow in the system.

Ed


The only reason I could think of on why the oil pressure gauge would read higher than the pumps relief pressure setting is because it's possible the relief valve can not bypass all the excessive flow 100% effectively and that in turn will allow the pumps output to exceed the relief pressure setting. Imagine a relief valve that really didn't relieve very well ... where must the excess volume go? ... through the engine, which will increase the supply pressure because the pump is forcing more oil down the engine circuit because the relief valve didn't do it's job 100% as designed. This could certainly happen in a cold oil flow senario.
 
Originally Posted By: Gary Allan
Quote:
You have to look at the entire SYSTEM to see what's going on.


I'm afraid that you don't. I don't have to know internal pump head or anything that you insist is essential to know/see the effects upon the filter. You seem to be unable to divorce Bernelli from the undeniable physical events and give them powers that aren't essential to understanding what occurs (more often then not).


You wouldn't know Bernoulli if he bit you in the arse!
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[censored], you can’t even spell it right.

Gary - I want to know why YOU think Subaru has specified a 23 psi relief setting on their oil filters. Tell us why if there is no pressure drop factor in a filter with high volume flow going through it.
 
Quote:
I've concluded that these discussions are nothing but a frickin game for you. Everything I say, which by the way is usually correct, you find some way to twist it up in your head just to stir up sh*t. I could try to explain this stuff until I'm blue in the face and you would never admit that you're thinking is messed up on some of this stuff.


I've concluded that these discussions are nothing but a frickin' game for you in self ego massaging. Everything I say, which, btw, is based 100% on real physical events, gets ignored and can't be envisioned nor integrated by your mindset and stubborn need to see garden hoses where none exist. I keep looking for you to bring something to the table that falls outside this one dimensional view ..and see nothing. You insist on twisting it back to a garden hose with applied pressure over a variable resistance ..which is not how the system reacts.

Quote:
If you don't think an oil filter can contribute to flow restriction in the oil system,


Oh, here's where you fail the test 100% of the time. I've only insisted that a filter cannot alter the flow rate if the pump is not in relief.

You can read that statement, can you not? How does a pump producing 12gpm have its flow altered? Assuming it is not in relief, the pressures can vary ..but not the flow (again, for discussion's sake assume near 100% efficiency).

How hard is that to see?
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Oh ..the link? Don't doubt the observed data at all. The guy surely isn't a liar. You've found another exceptional circumstance to bolster a flaw premise..

Flow can be altered...

BUT NOT WITHOUT CREATING ENOUGH RESISTANCE TO CAUSE A RELIEF EVENT AT THE PUMP.

This is a way exceptional event in millions upon millions of engine that putt-putt around in ignorant bliss and never see an appreciable PSID event beyond start up.
 
Quote:
FWIW, my WRX read ~100 psi cold, a common reading seen by those with gauges. This is above the 85 psi relief setting specified for the pump. Mine was reading at the top, back of the block in the main galley. This was essentially the greatest distance possible from the pump(lower front of engine).


Thank you for being one owner with a gauge. Your pump output, at startup visc, is in excess of what the engine and the relief can process and remain @ 85 PSI line pressure. You ARE in a garden hose scenario with the filter being limited in resistance to the flow being maxed @ 23 PSI ADDED to the circuit. Once you pull off of 85lb (as read off the pump)..there's no relief event ..that differential will retreat. If the sensor is downstream (which it appears that it is) then you would see 123+lb if you tapped in above the filter if your downstream is 100psi+/-.

Quote:
There is obviously a restriction to flow in the system.


There is a resistance to flow passing an irresistible flow at a given rate(non-relief). It's evidenced by pressure elevations where the flow changes in velocity.

This is where SuperBusa (and just about everyone else) misses it.

5gpm through the Holland Tunnel
5pm though a capillary tube.

Once you accept that both DO IN FACT PASS THE FLOW ..the only difference is velocity and the pressure developed to do the job. Since we surrender to the (imperfections in pump efficiency ignored for discussion - making assertions MORE true than untrue)) fact that a positive displacement pump will pass a given volume at a given pump speed ..there's really not much else to argue with. The internal physics of the pump really doesn't need to enter into the discussion.
 
Quote:
Gary - I want to know why YOU think Subaru has specified a 23 psi relief setting on their oil filters. Tell us why if there is no pressure drop factor in a filter with high volume flow going through it.


I've stated this a few times ..but if you need a refresher..

Events @ 12.4 gpm = few
Events at startup relief = many


There are obviously limits to anything. The outlet port size of the pump will (probably) come into play at some point. I imagine that this is why pumps are typically rated with some terminal volume at some given pump speed. The internal pump outlet port, at some point, causes its own relief event. I've seen SBC racers machining out the gear side outlets to enable higher flow ...

So? How this upper strata limit alters flow is still missing in anything you've presented, SuperBusa.

12.4gpm @ 23 PSID at the filter
12.4gpm @ 11 PSID at the filter (non-spec)

The difference? 12.4gpm will be composed of more or less filtered oil depending on which filter you use...but it will still be 12.4gpm of flow.

Start up (and probably a good bit through the warm up event).

More oil will be filtered while limiting the maximum resistance to flow that a filter can present in a pressure over resistance flow scenario that is only possible in a pump relief event.
 
Originally Posted By: Gary Allan
Quote:
I've concluded that these discussions are nothing but a frickin game for you. Everything I say, which by the way is usually correct, you find some way to twist it up in your head just to stir up sh*t. I could try to explain this stuff until I'm blue in the face and you would never admit that you're thinking is messed up on some of this stuff.


I've concluded that these discussions are nothing but a frickin' game for you in self ego massaging. Everything I say, which, btw, is based 100% on real physical events, gets ignored and can't be envisioned nor integrated by your mindset and stubborn need to see garden hoses where none exist. I keep looking for you to bring something to the table that falls outside this one dimensional view ..and see nothing. You insist on twisting it back to a garden hose with applied pressure over a variable resistance ..which is not how the system reacts.


You're the ego maniac here on this board ... I can sense it. You can't stand it if someone challenges your "supreme thoughts", and especially if they are right and you are wrong. You think you're always right, but there are plenty of things you don't quite grasp just yet, and frankly probably never will because you really do NOT understand fluid flow physics enough to see through your fogged up thoughts.

Originally Posted By: Gary Allan
Quote:
If you don't think an oil filter can contribute to flow restriction in the oil system,


Oh, here's where you fail the test 100% of the time. I've only insisted that a filter cannot alter the flow rate if the pump is not in relief.

You can read that statement, can you not? How does a pump producing 12gpm have its flow altered? Assuming it is not in relief, the pressures can vary ..but not the flow (again, for discussion's sake assume near 100% efficiency).

How hard is that to see?
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This is where you don't get it - I have never claimed that the oil filter controls the flow rate through it. My claim is THAT THE FLOW THROUGH THE FILTER CAUSES A PRESSURE DROP ACROSS THE FILTER EMEMENT. When I say the words "FLOW RESTRICTION" I mean the filter is adding RESISTANCE TO FLOW. It does NOT mean that the filter is making the oil pump flow rate go DOWN ... you ARE ASSUMING THAT for some reason. Hence, this comes right around full circle with my claim (that you don't believe) that IF you put THE SAME FLOW RATE through a HIGHER FLOW RESISTANCE that the PSID across that resistance will INCREASE. Get it ???


Originally Posted By: Gary Allan
If the pump is NOT in relief then ALL of its flowrate is going to the filter. Any you are claiming that with ALL the flow going through the filter that there isn't a significant PSID across the filter element? Come on man, are you serious?


Dude ... PLEASE re-read this stuff. See above ... you derailed some time ago it seems. I've ALWAYS CLAIMED that the MORE VOLUME YOU PUT THROUGH A FILTER THE GREATER PSID YOU WILL HAVE ACROSS THAT FILTER. Get a grip and learn how to frickin' read! And I'm NOT going to "hold your hand" and go back to point out every place I've described the physics. Instead, if you're so hot to prove me wrong, you can go back and find exactly where I've claimed differently.

Originally Posted By: Gary Allan
Oh ..the link? Don't doubt the observed data at all. The guy surely isn't a liar. You've found another exceptional circumstance to bolster a flaw premise..

Flow can be altered...

BUT NOT WITHOUT CREATING ENOUGH RESISTANCE TO CAUSE A RELIEF EVENT AT THE PUMP.

This is a way exceptional event in millions upon millions of engine that putt-putt around in ignorant bliss and never see an appreciable PSID event beyond start up.


Don't get distracted from the test results. There was NO relief valve in the test. The pump was turned up until the SAME FLOW RATE was put through each filter, and then the PSID was seen. Obviously, not all filers are the same ... and they CAN have a somewhat significant PSID depending on the FLOW RATE and oil VISCOSITY going through them. And to add (and the reason for this thread), if the bypass valve is not set correctly for a filter's application then the PSID will be high enough to get unwarranted bypass events. This isn't rocket science, now is it?
 
Originally Posted By: Gary Allan
Quote:
Gary - I want to know why YOU think Subaru has specified a 23 psi relief setting on their oil filters. Tell us why if there is no pressure drop factor in a filter with high volume flow going through it.


I've stated this a few times ..but if you need a refresher..

Events @ 12.4 gpm = few
Events at startup relief = many


There are obviously limits to anything. The outlet port size of the pump will (probably) come into play at some point. I imagine that this is why pumps are typically rated with some terminal volume at some given pump speed. The internal pump outlet port, at some point, causes its own relief event. I've seen SBC racers machining out the gear side outlets to enable higher flow ...

So? How this upper strata limit alters flow is still missing in anything you've presented, SuperBusa.


Sure, even a PDP can't have a linear output forever. But, I think the pump will perform relatively linear up to it's relief pressure setting. It wouldn't make sense to design a pump application for an engine that fell on it's face (output vs speed wise) way before the relief setting. If you believe that oil pump performance spec from Subaru, it says that the pump can put out 12.4 gpm at 5000 RPM. It also says that it takes 43 psi of pressure to push that 12.4 gpm of oil at 176 deg F (viscosity qualifier) through the oiling system of that Subaru engine - that gives you an idea of how restrictive the oil system is on that car ... not very IMO, otherwise it would take a whole lot more than 43 psi to flow that much oil warm through it. At least that's how I read it.

Originally Posted By: Gary Allan

12.4gpm @ 23 PSID at the filter
12.4gpm @ 11 PSID at the filter (non-spec)

The difference?
12.4gpm will be composed of more or less filtered oil depending on which filter you use...but it will still be 12.4gpm of flow.

Start up (and probably a good bit through the warm up event).

More oil will be filtered while limiting the maximum resistance to flow that a filter can present in a pressure over resistance flow scenario that is only possible in a pump relief event.


I'm assuming you mean 23 and 11 psi bypass valves ... not PSID (see red).

The difference is, IF both filter's elements had the same resistance to flow, then the PSID should be the SAME in both filters if 12.4 gpm of flow is put through them both. The big difference then would be that the filter with the 11 psi bypass valve will go in to bypass much more often, and bypass events could happen even if the oil is relatively warm. This is the exact reason Subaru has specified a higher bypass valve setting ... to keep bypass events down to a minimum. Will it prevent them all? ... probably not - but, it will definitely keep the frequency down to a minimum.
 
I am a bit late but FWIW, 43 psi is the minimum pressure at 5K rpm.
Originally Posted By: 2003 service manual

Oil pressure:
98 kPa (1.0 kg/cd, 14 psi) or more at 800 rpm
294 kPa (3.0 ks/cd, 43 psi) or more at 5,000
rpm


I see ~100 psi at cold start, and WELL more than 43 psi above 5K rpm, @ 180 oil temp, and around 20-25 psi at idle.

I have oil temp and pressure gauges.
 
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