High Flow Oil Filter

[ZeeOSix]

Originally Posted By: Gary Allan
Alright, you sucked me into one last round Soopah-Boosah (Jabba speak)

A filter just is a tremendous restriction compared to an empty pipe ..how hard is that to see? Not hard at all.

Try pouring or pumping oil ..at any temp ..etc. ..through a filter instead of just an empty pipe. Are you saying that they're equal? That a sheet of porous paper is capable of passing fluid as though it's not there?

Of course you're not. Only a flaming fool would believe such nonsense unless he was profoundly disturbed and off his meds.

I think we can agree there, right?

If you've got anything other than a YES or NO answer before your predicted dissertation, we're done.


Yes ... I agree, an oil filter is more restrictive than a big empty pipe when comparing the two. Be nice now Mr. Allan. Next step please.

 

[Gary Allan]

So, you can now see how there will be a pressure differential across the filter? Now we'll attempt to see how that DIFFERENTIAL evaporates ..at least most of it.

I anticipate that here we'll have our next divide. I believe that you reason since the filter will pass MUCH more fluid later on (after startup) that the PSID will be low at start up and progress from there.

Would that be correct?

 

[ZeeOSix]

Originally Posted By: Gary Allan
So, you can now see how there will be a pressure differential across the filter? Now we'll attempt to see how that DIFFERENTIAL evaporates ..at least most of it.


Yes, there will be a PSID across the filter. But the PSID value will be dependent on the GPM flow & viscosity coming out of the positive displacement oil pump.


Originally Posted By: Gary Allan
I anticipate that here we'll have our next divide. I believe that you reason since the filter will pass MUCH more fluid later on (after startup) that the PSID will be low at start up and progress from there.

Would that be correct?


No ... the filter will pass the same GPM before the oil hits the engine as it will after the oil hits the engine if the pump is running at a constant speed and doesn't go into relief. The oil pump’s output pressure will be very low until the oil hits the restrictive engine, then the pump’s output pressure will build ... but the GPM flow will still be the same. This means the oil pump has to run at a much higher pressure (ie, 50 PSI) when the oil hits the engine in order to keep pushing that constant 3 GPM through a much more restrictive flow path.

Assume the pump is not in relief and the filter’s bypass is closed ... then:
The filter is passing whatever oil flow the positive displacement pump is putting out. If the pump is sending 3 GPM to the filter, then 3 GPM is going through the filter. If there is no back pressure on the filter, then the pump doesn’t have to work very hard at all to pass 3 GPM through the filter - because an oil filter isn't very restrictive.

If the filter had 1 PSID with 3 GPM of flow, then the pump only has to produce 3 PSI of supply pressure on the filter's inlet to push the oil through it. I think this is the part you are missing.

Can you put some numbers (pump pressure, filter PSID, GPM) on your two sketch examples to help tie this together?

 

[Gary Allan]

Quote:
Yes, there will be a PSID across the filter. But the PSID value will be dependent on the GPM flow & viscosity coming out of the positive displacement oil pump.


Sure in an open pipe, as described, and with no other downstream restrictions that trump it.

So, SURE, under THOSE CONDITIONS ..assuming a constant fluid visc and ignoring any potential turbulent contributions with a million little orifices involved. I can agree to that.

As I said, "terms and conditions apply" (you are Soopah-Boosah no one else would keep trying to insert oddball stuff to object to after moving half way to conceding

)

SOOOOOOPY!!! How the heck are ya, pal!!

 

[ZeeOSix]

Originally Posted By: Gary Allan
Quote:
Yes, there will be a PSID across the filter. But the PSID value will be dependent on the GPM flow & viscosity coming out of the positive displacement oil pump.


Sure in an open pipe, as described, and with no other downstream restrictions that trump it.

So, SURE, under THOSE CONDITIONS ..assuming a constant fluid visc and ignoring any potential turbulent contributions with a million little orifices involved. I can agree to that.


This is where you are missing the boat Mr. Allan: ---> How can the PSID across the filter change if the GPM and viscosity remains constant?

Again, assume the viscosity is constant. If that positive displacement oil pump is running at 1000 engine RPM all the time, then the flow rate coming out of the pump will always be the same - agree?

The flow rate through the filter will determine its PSID. Same goes with an engine. The oil pressure at an engine's inlet (where the oil pressure sensor is located) is dependent on how much GPM is going through it - agree?

You need to see that in order to realize that in your two sketches that the PSID across the filter will be the same in both cases if that oil pump is putting out the same GPM in each case.

Question: Is that oil pump putting out the same GPM in both cases? If not, why? You ignore my questions for some reason.

Originally Posted By: Gary Allan
As I said, "terms and conditions apply" (you are Soopah-Boosah no one else would keep trying to insert oddball stuff to object to after moving half way to conceding

)

SOOOOOOPY!!! How the heck are ya, pal!!

Don't know what all this "Soopah-Boosah" (sounds kind of like James Bond

) and this "Sooooopy" stuff is, but must be a long lost buddy or something.

 

[ZeeOSix]

This is interesting ... I found this old quote which makes perfect sense and is what I'm trying to convey. Why don't you agree with your own words you said way back back in 09/01/03?

Originally Posted By: Gary Allan
If I'm not mistaken, Bob is adjusting the inlet pressure for each filter to reach 40psi and then checking the outlet pressure? If that is the case we are unable to tell what backpressure is present? Am I mistaken Bob or are you not making any adjustments of the inlet pressure? I wonder what the situation would be if he merely had the same pump output on the various filters. The oil pump is positive displacement. At xxx rpm is will flow so much oil. This would be a better test for filter resistance ...but the reading might be much lower and variable in amplitude and differential making it hard to compare.

The way I guess you could do this is to set up a metered orfice (at the end of the return line) with a fixed oil pump rpm and oil temp that would give you a stable "static baseline flow" (without any filters installed). Then the filter would only "add" inline restriction ...and a subsequent pressure/flow drop.

Right now were providing the same supply pressure ...which could vary considerably on the actual flow through the filter(s).


Quote was from this thread:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=315299&page=1

 

[Gary Allan]

Quote:
How can the PSID across the filter change if the GPM and viscosity remains constant?





When the pressure behind the filter increases to (nearly) match the applied pressure. This would all, naturally, be in "transition" from startup to engine envelopment.

Nothing else changes. The volume is the same ..the visc ..whatever.

Once the engines enveloped ..the PSID evaporates to not worth mentioning. The filter then becomes just (ALMOST) another piece of pipe that's not an issue of merit for MOST applications up to the full output capacity of the engine ..if one could really live there on MOST cars in MOST environments.

Quote:
Again, assume the viscosity is constant. If that positive displacement oil pump is running at 1000 engine RPM all the time, then the flow rate coming out of the pump will always be the same - agree?


Sure.

Quote:
The flow rate through the filter will determine its PSID.


Not in this case. Again, in an open pipe that doesn't transition to some extreme choke. Sure. This would be because the down stream pressure development would be low to none. The ONLY thing developing pressure would be the filter. Between it and the pump. No engine to develop its "back pressure".

Quote:
The oil pressure at an engine's inlet (where the oil pressure sensor is located) is dependent on how much GPM is going through it - agree?


Agreed. The filter "stacks on top of" that developed pressure. The engine is incredibly more restrictive than the filter, hence it produced the MEGA LION'S SHARE of the TOTAL PRESSURE of the circuit.

Quote:
You need to see that in order to realize that in your two sketches that the PSID across the filter will be the same in both cases if that oil pump is putting out the same GPM in each case.


Not on this corporeal/dimensional plane. Your physics won't work here. You dialed the wrong portal address.

Quote:
Is that oil pump putting out the same GPM in both cases? If not, why?


They're the same. One is at startup with an empty engine (not fully enveloped) ..and the other is a few seconds later ..after the engine is fully enveloped.


Quote:
You ignore my questions for some reason.


No. I just handle one detour at a time

 

[ZeeOSix]

Originally Posted By: Gary Allan
Quote:
How can the PSID across the filter change if the GPM and viscosity remains constant?


When the pressure behind the filter increases to (nearly) match the applied pressure. This would all, naturally, be in "transition" from startup to engine envelopment.

Nothing else changes. The volume is the same ..the visc ..whatever.


But even during this transition, the GPM going through the filter is the same and remains constant, so that means the PSID will remain constant. PSID across any flow element does not depend on back pressure. An engine has 0 PSI back pressure on it ... yet, it has a given PSID with X GPM flow. This is the fact that you are always mis-understanding.

The same hold true for just the filter ... it will develop the same PSID with 0 PSI back pressure as it will with 100 PSI back pressure.

Originally Posted By: Gary Allan
Once the engines enveloped ..the PSID evaporates to not worth mentioning. The filter then becomes just (ALMOST) another piece of pipe that's not an issue of merit for MOST applications up to the full output capacity of the engine ..if one could really live there on MOST cars in MOST environments.


Actually, once the engine is enveloped, the GPM flow is STILL the same GPM (if the engine speed is constant) and the oil pump supply pressure has now risen quickly from just a few PSI while the flow was just going through the filter to a much higher PSI (say 50 PSI) it takes to force that same exact GPM through the filter + engine.

Towards the end of that old Oil Filter Test thread of Bob’s way back when [ http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=315299&page=1 ], you seem to understand it correctly just as I’ve explained.

Originally Posted By: Gary Allan
Quote:
The flow rate through the filter will determine its PSID.


Not in this case. Again, in an open pipe that doesn't transition to some extreme choke. Sure. This would be because the down stream pressure development would be low to none. The ONLY thing developing pressure would be the filter. Between it and the pump. No engine to develop its "back pressure".


So tell me what the oil pump pressure would be in the case with JUST the filter (sketch #1) vs. the case with the filter + engine (sketch #2)?


Originally Posted By: Gary Allan
Quote:
The oil pressure at an engine's inlet (where the oil pressure sensor is located) is dependent on how much GPM is going through it - agree?


Agreed. The filter "stacks on top of" that developed pressure. The engine is incredibly more restrictive than the filter, hence it produced the MEGA LION'S SHARE of the TOTAL PRESSURE of the circuit.


True, the filter adds the relatively small amount of PSID it produces. So if there is only a filter in the system (ie, your sketch #1), how much oil pump pressure do you think would be needed to push X GPM through only the filter? And then once the oil hits the engine, how much oil pump pressure do you think would be needed to push that same GPM through the filter + engine? Give me some relative numbers to help explain what you think is going on with the pump pressure between sketch #1 and sketch #2.

Originally Posted By: Gary Allan
Quote:
Is that oil pump putting out the same GPM in both cases? If not, why?


They're the same. One is at startup with an empty engine (not fully enveloped) ..and the other is a few seconds later ..after the engine is fully enveloped.


True, they are the same. This again means that if the same GPM and same viscosity oil is going through the same filter in both sketches then the PSID across the filter will be the same. The filter will build the same PSID regardless if it has 0 PSI of back pressure, 100 PSI of back pressure or 300 PSI of back pressure.

 

[Gary Allan]

Quote:
But even during this transition, the GPM going through the filter is the same and remains constant, so that means the PSID will remain constant.


No, it wouldn't. Here we are at a detour. The rest of your post has to wait.

 

[ZeeOSix]

Originally Posted By: Gary Allan
Quote:
But even during this transition, the GPM going through the filter is the same and remains constant, so that means the PSID will remain constant.


No, it wouldn't. Here we are at a detour. The rest of your post has to wait.


Then please explain exactly why by using numbers on your two sketches to show what you think is going on in terms of pressure and flow before and after the filter.

I wouldn't call it a "detour", as this is a major focus point in the discussion ... in fact the main point of the discussion IMO.

To clarify, when I say "during this transition", I mean that the filter has been fully enveloped with oil and oil is flow out past the filter at the X GPM the pump is putting out, but the oil has not yet hit the engine. Assume the distance between the filter and engine is quite a long ways in your two sketches and it takes a while for the oil to reach the engine.

 

[Gary Allan]

Quote:
Then please explain exactly why by using numbers on your two sketches to show what you think is going on in terms of pressure and flow before and after the filter.


No, why don't you tell me what you think is going on in terms of numbers ..and more importantly ..WHY you think it works that way?

If it can't work my way ..and under constant viscosity and constant flow rate, your assertion would mean that the filter would never come off of bypass if the PSID was at that level. Never ..since, again under your assertion, the PSID would be "absolute" and would always be the same at that visc/flow rate.

It's not, it's relative.

 

[ZeeOSix]

Originally Posted By: Gary Allan
Quote:
Then please explain exactly why by using numbers on your two sketches to show what you think is going on in terms of pressure and flow before and after the filter.


No, why don't you tell me what you think is going on in terms of numbers ..and more importantly ..WHY you think it works that way?


I've put numbers on both figures a number of times already in this thread, so just go back and re-read the info. Read this post carefully, it gives examples with numbers and sums it up clearly.

http://www.bobistheoilguy.com/forums/ubb...928#Post2042928

Originally Posted By: Gary Allan
If it can't work my way ..and under constant viscosity and constant flow rate, your assertion would mean that the filter would never come off of bypass if the PSID was at that level. Never ..since, again under your assertion, the PSID would be "absolute" and would always be the same at that visc/flow rate.

It's not, it's relative.


In my examples with numbers put to the figures, the filter would never be in bypass (GPM assumed reasonable) and have the same exact PSID in both scenarios - I've explained why many times.

You don't think that's true, so I need some numbers from you put to your examples so I can try to understand where you're coming from on this.

 

[Gary Allan]

Quote:
I've put numbers on both figures a number of times already in this thread, so just go back and re-read the info.


Well, first I come to a detour and will continue to stop at the first detour I run into. When that's settled, we can move on.

Hey, don't make me go back and quote you where you said you wanted to take it one piece at a time. Soopah-Boosah


Quote:
If the low restriction filter is the only component the oil is flowing through (sketch #1), the oil pump will NOT produce the same supply pressure that it will have to supply when the flow starts hitting the much more restrictive engine circuit.


You assume that the filter appears to be low restriction at that time. We can't go on from there if you can't see that a choke only appears like a choke if there's nothing behind it.

You assume that the pump will acquire no pressure ..pumping through the media of the filter ..and not have ANY (nor nearly as much) pressure YET developed on the engine side,

This concept is not hard to figure.

 

[Gary Allan]

I'm waiting for the "hot oil" recurring theme to show up. Maybe it's been replaced with "low restriction filter" this round. You can really tell by the limited posting. Soopah-Boosah (imagine Jabba the Hut voice).

 

[ZeeOSix]

Originally Posted By: Gary Allan

Quote:
If the low restriction filter is the only component the oil is flowing through (sketch #1), the oil pump will NOT produce the same supply pressure that it will have to supply when the flow starts hitting the much more restrictive engine circuit.


You assume that the filter appears to be low restriction at that time. We can't go on from there if you can't see that a choke only appears like a choke if there's nothing behind it.


The filter has a low restriction to flow (relative to the engine) at all times. The filter can only "choke" so much based on it's fixed flow resistance factor, regardless if there is 0 PSI of back pressure or 100 PSI of back pressure on the filter.

If a filter was as restrictive as you think with no back pressure on it, then if you poured oil down a filter's center tube it would never flow one drop of that oil. Everyone knows that's not true.

Originally Posted By: Gary Allan

You assume that the pump will acquire no pressure ..pumping through the media of the filter ..and not have ANY (nor nearly as much) pressure YET developed on the engine side,

This concept is not hard to figure.


It's not an assumption, it's a fact. A positive displacement pump putting out a fixed X GPM will only build up it's output pressure depending on how much resistance it is pumping against. That's why the pump's output pressure will be very low while pumping oil through the filter only, and will not build up pump pressure until the oil flow hit's the much more restrictive engine. It seems you don't think that is what really happens.

Question - What do you think the oil pump's output pressure is while pumping X GPM only through the filter vs. the oil pump's output pressure when that same X GPM is being pumped through the filter AND the engine?

 

[Gary Allan]

(imagine me whistling and gazing at nothing)

Soopah-Boosah

 

[Doug Hillary]

Hi,
Flow characteristics within engine lubrication systems vary considerably. It is not a “one size fits all” argument IMO as in the last several decades they have become very complex. Some engines now have several oil pumps and some are electrically driven and computer controlled

Donaldson carried out many tests when developing their Synteq synthetic filtration (fluid) media used in their Endurance range of FF filters. I was so interested in this and their EON synthetic media air cleaners that I prevailed on them here (they manufacture here too) around 1999 to import and sample the marketplace

I was the first serious user of their Synteq FF filters (and EON air filters) here in OZ and carried out my own testing in parallel with a centrifuge bypass cleaner. What interested me about their testing which was carried out in the 1990s was the time the average cellulose FF filter spent in media bypass compared with their Synteq media.

The following averaged data emerged;

Engine speed: at idle Lubricant: 15W-40 mineral HDEO
By-pass operating range: 15-22psi

At an oil temperature (OT) of 40C Synteq - restriction at 15psi – off media bypass

At an OT of 70C with cellulose media – restriction at 15psi – off media bypass

At an OT of 70C Synteq had 5psi restriction (one third of the cellulose media)

At an OT of 100C Syntec had 2.5psi restriction and cellulose had 5psi (Synteq was only 50% of cellulose media)

So, in the OT range from 40C to 70C the Synteq media was able to flow more lubricant in the critical period when temperature sensitive AW additives were just commencing their task
Of course these figures become more relevant as RPMs rise and most especially so with a cold lubricant

In my small Fleet I finally changed to stainless steel 35micron cleanable mesh FF inserts and a 5W-40 synthetic HDEO. This move meant that media restriction was insignificant thereby providing full flow to the lubrication system and better flow to the centrifuge even with a cold lubricant

For what it's worth.............

 

[Gary Allan]

Yes, indeed, Doug. However, we're talking in isolation of a pump, a filter, and a complex downstream restriction that we could care less about as long as it's fundamentally fed by a single pipe.

I do thank you for the introduction to the newer and much more sophisticated systems.

I do need to question your data. Not for validity ..but for conditions. The only time I've ever seen PSID of merit was when the pump was in relief. Otherwise, it HAS to be subordinate to the fundamental by an incredible margin.

The one exception being with a heavily loaded filter before full oil warm up. It basically simulated a much smaller filter and there would be "surge" as you ran the rpms up. Those conditions are not being discussed here.

 

[ZeeOSix]

Originally Posted By: Doug Hillary
I was the first serious user of their Synteq FF filters (and EON air filters) here in OZ and carried out my own testing in parallel with a centrifuge bypass cleaner. What interested me about their testing which was carried out in the 1990s was the time the average cellulose FF filter spent in media bypass compared with their Synteq media.

The following averaged data emerged;

Engine speed: at idle Lubricant: 15W-40 mineral HDEO
By-pass operating range: 15-22psi

At an oil temperature (OT) of 40C Synteq - restriction at 15psi – off media bypass

At an OT of 70C with cellulose media – restriction at 15psi – off media bypass

At an OT of 70C Synteq had 5psi restriction (one third of the cellulose media)

At an OT of 100C Syntec had 2.5psi restriction and cellulose had 5psi (Synteq was only 50% of cellulose media)


Makes perfect sense, and is in parallel with what I’ve been saying all along. In all your cases the engine was at idle, so this means the flow volume coming out of the oil pump was a constant GPM.

The cases you show where the oil is the same temperature (ie, viscosity) clearly indicates that some filters can be much more restrictive than others when the same flow and viscosity is going through them.

An oil filter has “a fixed flow restriction factor”, and so the PSID across the filter will be solely a function of the oil flow volume (GPM) going through it and the oil’s viscosity. The oil filter can care less if the oil pump is in pressure relief or not or if there is any significant back pressure on it. All an oil filter cares about is the GPM and viscosity going through it, which results in the specific PSID associated with those two conditions.

Originally Posted By: Doug Hillary
Of course these figures become more relevant as RPMs rise and most especially so with a cold lubricant


Absolutely … the filter’s PISD will increase proportionately to the increase in flow (increase in GPM) from the pump, and also from the increase in oil viscosity. You seem to have a good handle on it all. Thanks for your inputs.

 

[ZeeOSix]

Originally Posted By: Gary Allan
However, we're talking in isolation of a pump, a filter, and a complex downstream restriction that we could care less about as long as it's fundamentally fed by a single pipe.


But your first figure is still not an accurate depiction of what actually happens with just the filter in the flow path, so give us some numbers with your two figures so we can see what you’re talking about - or are you afraid to do so?

Originally Posted By: Gary Allan
I do need to question your data. Not for validity ..but for conditions. The only time I've ever seen PSID of merit was when the pump was in relief. Otherwise, it HAS to be subordinate to the fundamental by an incredible margin.


Of course you’re going to see the highest PSID across an oil filter when the oil pump is in relief … that’s because that is when the max pressure is coming out of the oil pump which means it’s also the time when the flow volume (GPM) is max (for the viscosity in hand) through the oil filter and engine.

And you should also be able to see less PSID values as the pump gets farther away from relief pressure, and as the oil viscosity decreases. That's why you see the highers PSID at redline and the lowest PSID at idle ... same with the engine oil pressure. Both the filter PSID and the engine's PSID go up and down in concert.