How to test opening PSI for oil filter bypass?

[Gary Allan]

Quote:
Don't confuse the oil pump going into pressure relief mode vs. the oil filter going into bypass mode. They are NOT related in any way.


False under most situations. Perhaps true in extremely limited circumstances.

The relief and bypass are reactive and interactive ..at least in "apparent" pressure differences.

IF you're not yet max'd out on volume and you're already at terminal PSID ..then ..sure. The filter will just sit there at its terminal PSID and pressures will increase.

However, at anything below that terminal throughput potential of the filter, EVERY increment of increased relief flow increases PSID.

 

[chunky]

Originally Posted By: SuperBusa
Don't confuse the oil pump going into pressure relief mode vs. the oil filter going into bypass mode. They are NOT related in any way. If the oil pump volume and oil viscosity is high enough before the pump ever goes into pressure relief, it's still possible to see the filter go into bypass mode. If the oil pump goes into pressure relief mode when there is a pretty small oil flow volume, then the filter bypass will probably hardly ever (maybe on extreme cold starts) or never go into bypass mode - as I said before, you could have high oil pressure and a relatively low flow rate depending on the resistance of the filter/engine circuit. Obviously, the performance characteristics of the oil pump and it's pressure relief setting are very important factors to this whole discussion.

Think of the oil pump as a voltage/current power supply. The pump's relief valve is like setting a voltage limit on the PS. If you put a max voltage across a fixed resistance you get a corresponding max current. The pump when in pressure relief mode is "ideally" trying to hold the oil pressure at a max constant, which in turn limits the flow volume to a max constant (assuming flow resistance and oil viscosity is constant).

All the pump pressure relief valve does in LIMIT the pressure being applied to the filter/engine circuit. As said before, depending on the oil viscosity, that applied pressure will determine how much of the pump's volume goes down the filter/engine circuit ... any excess volume output of the pump MUST go back to the sump via the relief valve circuit. I would imagine that most pump relief valves are low resistance to flow ... but even in your case it sounds like it can be "overpowered" by the pump and not relieve the excess volume 100% efficiently. That's when you see pump output pressure higher than the relief valve psi setting.


I have an old oil pump in the garage. I'll take a picture of the relief structure. From what I recall, the size of the relief outlet is rather small relative to the size of the oil pump's output.

So far it all makes sense. The oil pump relief works in a similar manner to a voltage regulator. It tries to limit the max pressure applied to the hydraulic circuit. A voltage regulator bleeds off current from the main supply and sinks it back to ground. It is in effect a variable resistor that reacts to changes in the input voltage.

 

[chunky]

Originally Posted By: Gary Allan
The relief valve and the bypass valve are reactive components. The engine is a static linear resistive element.

The engine will ALWAYS be a product of out traditional adaptive Ohms law equations. It's got on impedance factor to it. You pump x volume @ y visc ..you get P. This never changes at all under any circumstances. NEVER. Keep that in mind ..or see if Superbusa can convince you otherwise. Baloney can't argue with that one.

Can we agree on a number of givens?

Can we agree (super doesn't need to agree - he'll attempt to load on "riders" that will confound discovery

)

That the engine will be a linear model under any circumstances that we will discuss here. ????

Let's just take this one element at a time in "construction". I'm trying to limit the dissertations.



I can agree that the pump relief valve and filter bypass valve are reactive elements. Probably similar to the function of a capacitor which obeys the equation: current = capacitance * d(voltage)/d(time). There's probably a similar equation for the pump relief valve and filter bypass valve. The filter itself is still a plain ol restrictive element.

Now as far as the engine being modeled as a linear element, yes, I can buy that both the engine and the filter element could be linearly modeled. It seems probable that they have a linear range of operation, in steady state of course.

 

[Gary Allan]

Quote:
The filter itself is still a plain ol restrictive element.


There's the rub. It's not. It evidences the regulated pressure above ..and the product of Ixr below. It "expresses" the divergence of flow in it's PSID when in relief.

Out of relief, it's a minor resistive element ..like a section of big pipe. It's only at its throughput limits that an impedance produces pressure drop across it.

 

[chunky]

I did get my oil analysis results today. Posted them here:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1519061

Everything looks good on that front.

Now, I just need to take my PSID measurements under track driving conditions and see if I'm exceeding the 12psi that the filter bypass is rated for.

 

[chunky]

Originally Posted By: Gary Allan
Quote:
The filter itself is still a plain ol restrictive element.


There's the rub. It's not. It evidences the regulated pressure above ..and the product of Ixr below. It "expresses" the divergence of flow in it's PSID when in relief.

Out of relief, it's a minor resistive element ..like a section of big pipe. It's only at its throughput limits that an impedance produces pressure drop across it.


It has to be a plain old resistive element. I'm not talking about the valve or anything else, just the filter media. It's just a simple restrictive element.

 

[SuperBusa]

Originally Posted By: chunky
Originally Posted By: Gary Allan
Quote:
The filter itself is still a plain ol restrictive element.


There's the rub. It's not. It evidences the regulated pressure above ..and the product of Ixr below. It "expresses" the divergence of flow in it's PSID when in relief.

Out of relief, it's a minor resistive element ..like a section of big pipe. It's only at its throughput limits that an impedance produces pressure drop across it.


It has to be a plain old resistive element. I'm not talking about the valve or anything else, just the filter media. It's just a simple restrictive element.


Yes, the filter media is a fixed flow resistor ... simple as that. Of course, as it loads up with crud, the resistance of the media becomes even greater. The higher the oil volume going through it, and the higher the oil viscosity, the more PSID there is across the media.

Gary is just doing his "twist is up with nonsensical expressions" jive spin on the whole thing and throwing simple engineering logic out the window.

Originally Posted By: Gary Allan
Out of relief, it's a minor resistive element ..like a section of big pipe. It's only at its throughput limits that an impedance produces pressure drop across it.


What's in red above is entirely false. This is why it's hard to have these discussions sometimes ... because there is a lack of grasping the real physics involved with the filter's resistance to flow by some members.

There is ALWAYS some level of PSID across the filter media IF THERE IS FLOW THROUGH IT. It can not be any other way ... the laws of fluid dynamics dictates this fact. There is no magical world with oil filters where the PSID is zero and then all of a sudden jumps up to some large value. Even when there is a surge in oil volume through the filter, there is a direct and corresponding surge in PSID, which could possibly cause the filter bypass valve to open briefly.

Bottom line is (with the oil viscosity being constant) -- at ZERO oil flow volume the filter PSID is ZERO. As the oil flow volume increases, so does the filter's PSID. At MAX oil flow volume, the filter's PISD is also MAX. It's just that simple.

 

[Gary Allan]

Sorry, Soupy. I've seen it with my own eyes and shared it with many here. You ..have not.

Your truth lives and breaths in the upper strata of volume ..and that's about it. Even a 6' pipe will present resistive elements if you push enough through it.

..but chuckle with the ally that you think you have since his interest are centered around the same obscure realm that you seem to think is pertinent 24/7/365.

I'll probably have to go and do this again so you can come up with more qualifications and exceptions to bring up.

You can't wish things to be true, my friend ..no matter how firmly rooted your beliefs may be in misconceptions.

I have done these tests ..you have not.

Have a nice day

 

[SuperBusa]

Originally Posted By: Gary Allan
Sorry, Soupy. I've seen it with my own eyes and shared it with many here. You ..have not.

Your truth lives and breaths in the upper strata of volume ..and that's about it. Even a 6' pipe will present resistive elements if you push enough through it.

..but chuckle with the ally that you think you have since his interest are centered around the same obscure realm that you seem to think is pertinent 24/7/365.


Obviously, you are either NOT reading my stuff, or you can't read. I've said many times that this is for unique conditions and have QUALIFIED exactly what those conditions are.

Originally Posted By: Gary Allan
I'll probably have to go and do this again so you can come up with more qualifications and exceptions to bring up.

You can't wish things to be true, my friend ..no matter how firmly rooted your beliefs may be in misconceptions.

I have done these tests ..you have not.

Have a nice day

We have already gone round and round on this in the Subaru oil pump thread. Your test didn't tell anybody anything on how a high volume oil pump system has an effect on the filter's PSID and bypass operation. You think I always live in a dream world about this stuff, but you are actually the one who can't think outside the box based on some test you did on a 6 banger van that probably pumps 3 gpm max at redline.

Guess we will just have to wait for Chunky’s tests to see who’s living in that dream world.

 

[SuperBusa]

Originally Posted By: Gary Allan
The relief valve and the bypass valve are reactive components. The engine is a static linear resistive element.

The engine will ALWAYS be a product of out traditional adaptive Ohms law equations. It's got on impedance factor to it. You pump x volume @ y visc ..you get P. This never changes at all under any circumstances. NEVER. Keep that in mind ..or see if Superbusa can convince you otherwise. Baloney can't argue with that one.


Yes, there is no disagreement here ... and I've never argued any differently about the engine's circuit being a "fixed resistor" to flow.

But what you seem to fail to realize is that the oil filter is also a fixed resistor to flow. It's a separate fixed resistor that is in series with the engine's fixed flow resistor.

All flow that goes through the filter also goes through the engine. Both the filter and engine will have their corresponding PSID associated with the oil flow and viscosity going through them. Simple as that. The filter has no special or magical physical properties that makes it exempt for the laws of fluid dynamics.

Assume viscosity is constant for these examples. Let's say the pump outlet pressure is 80 psi and not in relief mode. This means there is a total of 80 psi drop from the inlet of the oil filter to the outlet at the sump (at 0 psi gauge pressure). In this case there might be 10 psi drop across the filter and 70 psi drop across the engine.

Let's say the pump outlet pressure is 30 psi (at idle). This means there is a total of 30 psi drop from the inlet of the oil filter to the outlet at the sump. There might be 3 psi drop across the filter and 27 psi drop across the engine.

If the pump has a pressure relief setting of say 100 psi, then any time the pump is in relief there will be a 100 psi drop from the inlet of the filter to the sump. In this case, there might be something like a 13 psi drop across the filter and a 87 psi drop across the engine. The PSID across BOTH the filter and engine will go up or down with an up or down change in pressure/flow.

Getting the idea of what's really going on with the oil system? I'll bet Chunky gets it.

 

[SuperBusa]

Originally Posted By: Gary Allan
Quote:
Don't confuse the oil pump going into pressure relief mode vs. the oil filter going into bypass mode. They are NOT related in any way.


False under most situations. Perhaps true in extremely limited circumstances.

The relief and bypass are reactive and interactive ..at least in "apparent" pressure differences.

IF you're not yet max'd out on volume and you're already at terminal PSID ..then ..sure. The filter will just sit there at its terminal PSID and pressures will increase.


My original statement (in red above) is really true ... the filter’s bypass valve could care less what the pumps relief valve is doing. The filter’s bypass valve only cares on how much PSID there is across the filter media, and is just waiting to start opening when the filter’s PSID is equal to the bypass valve setting.

Originally Posted By: Gary Allan
However, at anything below that terminal throughput potential of the filter, EVERY increment of increased relief flow increases PSID.


What the ??? .... you're gonna have to claify that one.

The filter can go into bypass way before the pump goes into relief. But, if the filter is not in bypass by the time the pump goes into relief, then the filter will never go into bypass under those same exact operational conditions. This is because once the oil pump hits relief mode, the volume going to the filter/engine circuit is (ideally) held to a constant ... UNLESS the pump relief valve allows the pump’s outlet pressure to rise above the relief setting (due to an ineffective relief valve system), which would theb cause even more flow volume and associated increase in filter PSDI, and potentially causing the filter’s bypass to open.

 

[SuperBusa]

Originally Posted By: chunky
Originally Posted By: Gary Allan
Quote:
The filter itself is still a plain ol restrictive element.


There's the rub. It's not. It evidences the regulated pressure above ..and the product of Ixr below. It "expresses" the divergence of flow in it's PSID when in relief.


It has to be a plain old resistive element. I'm not talking about the valve or anything else, just the filter media. It's just a simple restrictive element.


The way I think of it is: The oil filter is a plain old resistive circuit that has a bypass valve in parallel with it that (ideally) will not allow the PSID (voltage drop) to increase above a predetermined controlled level across the resistor.

Originally Posted By: Gary Allan
Out of relief, it's a minor resistive element ..like a section of big pipe. It's only at its throughput limits that an impedance produces pressure drop across it.


The filter produces SOME LEVEL OF PSID any time there is flow through it. With a large flow volume going through it (way under it’s “throughput limit”), there can still be a significant PSID depending on the combo of these three factors – oil viscosity, flow volume rate (gpm) and media resistance factor. It’s really NOT rocket science ... it’s simple fluid dynamics. I still can't figure out where Gary is missing the boat on this stuff ... he's got his own world of physics going on it seems ... but we still love him.

 

[Gary Allan]

Quote:
My original statement (in red above) is really true ... the filter’s bypass valve could care less what the pumps relief valve is doing. The filter’s bypass valve only cares on how much PSID there is across the filter media, and is just waiting to start opening when the filter’s PSID is equal to the bypass valve setting.


100% of the time? 24/7/365? Nope. Untrue ...FAIL!!

I assure you, Soupy .. every relief event has impact on PSID. It causes just about all meaningful PSID that there is ...EXCEPT for high volume limits of the filter.

Quote:
The filter can go into bypass way before the pump goes into relief.


Can ..is the operative word.

Quote:
which would theb cause even more flow volume and associated increase in filter PSDI, and potentially causing the filter’s bypass to open.


You've got to reword the rest of that ..but PSID is usually created when there is a loss of volume to the engine, reducing its "pressure drop" as you like to refer to it. Since the flow is reduced and the pressure drop over the engine is less than applied pressure, the PSID is elevated. Applied pressure upstream ...developed (or dropped) pressure due to flow through the linear resistive circuit (you conceded to this)..the filter is the bulkhead/choke/weir that reads the differential.

Soupy. All you have to get me to stop is to say, "Well, I don't know in the instances that you're speaking of, Gary. I'm only interested in high volume extreme situations. I admit that I've never done any of the testing that you have done, and I know you're not a liar and are telling me exactly what are the conditions that cause the most PSID to be realized over millions of engines and that your descriptions make the most sense that the bypass valve is there to protect millions of mundane engines ...and weren't put in there for just the Fast&Furious types that I seem to associate myself with ..even though I drive on surface streets. I could actually have most of my cars use a filter with no bypass valve ..since I think that they're only functional at the extreme limits of everyone's power band. Even the average Honda Civic using female office worker".

 

[SuperBusa]

Originally Posted By: Gary Allan
Quote:
My original statement (in red above) is really true ... the filter’s bypass valve could care less what the pumps relief valve is doing. The filter’s bypass valve only cares on how much PSID there is across the filter media, and is just waiting to start opening when the filter’s PSID is equal to the bypass valve setting.


100% of the time? 24/7/365? Nope. Untrue ...FAIL!!


Yes ... 100% of the time. The filer's bypass valve operates only based on filter PSID ... it could care less if the pump is in relief mode or not. The pump being in bypass mode or not has no bearing what-so-ever on what the filter bypass valve does or doesn’t do. ONLY the PSID across the filter, and the opening setting of the bypass valve, determines when the bypass valve operates.

Originally Posted By: Gary Allan
I assure you, Soupy .. every relief event has impact on PSID. It causes just about all meaningful PSID that there is ...EXCEPT for high volume limits of the filter.


Every pump relief event means that the filter's PSID has hit the max level at that particular point in time ... unless the pump's relief valve can't really control the pump's outlet pressure at its setting as discussed many times before. If the pump's relief valve allows the output pressure to "creep" above it's setting, then you will see more volume and PSID across the filter as well as across the engine.

Originally Posted By: Gary Allan
Quote:
The filter can go into bypass way before the pump goes into relief.


Can ..is the operative word.[/quote}

Nothing wrong with can ... better than "never ever" like you seem to claim.

Quote:
which would then cause even more flow volume and associated increase in filter PSDI, and potentially causing the filter’s bypass to open.


You've got to reword the rest of that ..but PSID is usually created when there is a loss of volume to the engine, reducing its "pressure drop" as you like to refer to it. Since the flow is reduced and the pressure drop over the engine is less than applied pressure, the PSID is elevated.


Higher PSID is NOT created when the flow volume goes DOWN ... that is IMPOSSIBLE! (Ref your text in red).

Any time you REDUCE FLOW through any fixed flow resistor, the pressure drop across it (PSID) will also be REDUCED (decrease). (Ref your text in blue). Your describing this stuff BACKWARDS .. no wonder your all cork screwed on this.

Originally Posted By: Gary Allan
Applied pressure upstream ...developed (or dropped) pressure due to flow through the linear resistive circuit (you conceded to this)..the filter is the bulkhead/choke/weir that reads the differential.


What the ???

I'm not sure if that is comprehendible or not ... but it sounds like your saying the filter is the choke point? Dude ... you lost me (and I'm sure everyone) there.

Originally Posted By: Gary Allan
Soupy. All you have to get me to stop is to say, "Well, I don't know in the instances that you're speaking of, Gary. I'm only interested in high volume extreme situations. I admit that I've never done any of the testing that you have done, and I know you're not a liar and are telling me exactly what are the conditions that cause the most PSID to be realized over millions of engines and that your descriptions make the most sense that the bypass valve is there to protect millions of mundane engines ...and weren't put in there for just the Fast&Furious types that I seem to associate myself with ..even though I drive on surface streets. I could actually have most of my cars use a filter with no bypass valve ..since I think that they're only functional at the extreme limits of everyone's power band. Even the average Honda Civic using female office worker".

... your grasping now, but that's OK. Just in case you didn't notice ... we ARE talking about high volume, high RPM racing engine type of conditions here. I've never claimed that every oil filter on the road is in bypass 50% of the time. If you can fine ONE quote from me that says otherwise, I'll delete my account from this board without saying another word. I've qualified these discussions MULTIPLE times, but you just don't seem to understand written English well enough to understand that. Start reading my comments so you can get keep up with the debate, or stop coming up with moronic replies that are destructive to the whole conversations at hand.

 

[Gary Allan]

Quote:
Yes ... 100% of the time. The filer's bypass valve operates only based on filter PSID ... it could care less if the pump is in relief mode or not. The pump being in bypass mode or not has no bearing what-so-ever on what the filter bypass valve does or doesn’t do. ONLY the PSID across the filter, and the opening setting of the bypass valve, determines when the bypass valve operates.


Will you hang your head in shame and eat crow if I produce video of the events? Or will you just whine and complain that the evidence was contrived? Do you really think that I pulled this out of my behind?


Please don't make me p'wn you, pal. Concede with dignity

 

[Gary Allan]

Quote:
Higher PSID is NOT created when the flow volume goes DOWN ... that is IMPOSSIBLE!

Sure it can. It does. Just that you can't get your head out of your ...er..cloud

Limit of pressure from the pump

85

reduced flow to engine

75

PSID 10 PSID.

Increase flow as the relief event ceases ...PSID evaporates to next to nothing (between inches of water column and 2psid).


P'WN'D

 

[Gary Allan]

Quote:
your grasping now, but that's OK. Just in case you didn't notice ... we ARE talking about high volume, high RPM racing engine type of conditions here.


Really?

Quote:
Yes ... 100% of the time.



Is that your "change up pitch"?

I'm done ..I really need to resist getting into this with you

 

[SuperBusa]

Originally Posted By: Gary Allan
Quote:
Yes ... 100% of the time. The filer's bypass valve operates only based on filter PSID ... it could care less if the pump is in relief mode or not. The pump being in bypass mode or not has no bearing what-so-ever on what the filter bypass valve does or doesn’t do. ONLY the PSID across the filter, and the opening setting of the bypass valve, determines when the bypass valve operates.


Will you hang your head in shame and eat crow if I produce video of the events? Or will you just whine and complain that the evidence was contrived? Do you really think that I pulled this out of my behind?

Please don't make me p'wn you, pal. Concede with dignity

When you can come up with a real test setup (instead of your Mickey Mouse twin gauge setup) that can verify exactly what the filter PSID is, measure inlet pressure to the filter/engine circuit, exactly when the oil pump goes into relief, and exactly when the filter goes into bypass all collected and graphed in high speed data acquisition system ... then we can discuss it.

 

[SuperBusa]

Originally Posted By: Gary Allan
Originally Posted By: SB
Higher PSID is NOT created when the flow volume goes DOWN ... that is IMPOSSIBLE!

Sure it can. It does. Just that you can't get your head out of your ...er..cloud

Limit of pressure from the pump

85

reduced flow to engine

75

PSID 10 PSID.

Increase flow as the relief event ceases ...PSID evaporates to next to nothing (between inches of water column and 2psid).

P'WN'D

Gary ... seriously - really, how does the oil flow through the filter/engine go down when the oil pump if in relief mode at 85 psi? I really want to hear a clear explanation of that.

The amount of oil volume that goes down the filter/engine path is based on the inlet pressure (85 psi in your case) and the fixed resistance of the filter/engine path (assume oil viscosity constant as always).

Your example above says NOTHING. I want you to prove to me (and anyone else following along here), how the oil volume going through the filter/engine goes down just because the oil pump pressure is limited to a constant due to the pump going into relief mode.

This is were you are hosed up my friend. I’ve explained it many times that when the pump is in relief, and the oil pump output pressure is at it’s max at that relief event at that very instance in time, that the oil flow is also at the MAX possible at that instance in time. And I'm not talking in super dynamic conditions (ie, revving the engine from idle to redline over and over while in neutral). Think more in terms of steady-state flow where things are not changing super fast.

If the pressure is maxed out at 85 psi, then the max possible oil flow volume at that instance in time is going down the filter/engine path ... EVEN IF THE PUMP IS IN RELIEF.

I’d like a CLEAR explanation how the flow GOES DOWN to the filter/engine when the pump goes into pressure limit (relief) mode. I'd really like to find out where you are misunderstanding the physics of an oiling system.

Originally Posted By: Gary Allan
I'm done ..I really need to resist getting into this with you

Yes, you better ... because at some point you're gonna realize you are looking at this stuff all cockeyed ... then who will be eating crow?

I’m really surprised that nobody besides Chunky gets this stuff ... maybe they do, but don't want to drive a sword through your skull making you realize you're wrong on some of this stuff.

 

[SuperBusa]

Originally Posted By: Gary Allan

Increase flow as the relief event ceases ...PSID evaporates to next to nothing (between inches of water column and 2psid).

P'WN'D

I think not ... listen carefully.

The reason the PSID "evaporates next to nothing" when the pump's "relief event ceases" is because the pump's output volume has decreased. The pump output flow has NOT increased when the pump goes out of relief mode ... it's totally impossible. I really think you are missing the boat that the EXCESS volume from the pump is the ONLY portion that is shunted back to the sump. The flow to the filter/engine at relief pressure is the MAX it can be for the pressure and viscosity at hand.

If the oil viscosity is constant, the positive displacement oil pump puts out a near linear flow volume vs. RPM. If the pump is in a relief mode, then that just means it is producing MUCH MORE flow volume than the pump's output pressure will allow to be PUSHED down the filter/engine flow path (ie, the fixed flow resistor).

In relief mode, that EXCESS oil volume is shunted back to the sump ... BUT, the flow volume associated at the relief pressure (say 85 psi) is still flowing down the filter/engine path just like it would if the pump was at 85 psi and NOT IN RELIEF mode. Get it? Maybe I'll have to draw you a diagram to help explain this. I know Chunky gets it.