Mini-update bypass test

Gary Allan · Apr 8, 2005

quote:

I don't think it will work like you describe. If the flow remains at 10 GPM the flow through the 20 foot section will remain the same with or without the 10 foot "choke" hose. When the 10 foot choke hose is added as a restriction the flow is still 10 GPM and the flow in the 20 foot section is the same, the flow in the 10 foot section increases in velocity and the oil pressure increases throughout the system (unless the pump releif valve opens) then the flow rate would drop below 10 GPM.

If I read what you posted correctly ..we're in agreement.

Merely manipulate the "choke" anyway you please to make it communicate what I'm trying to say.

Here's my "rub" and this may or may not (if one indeed exists) make the same bulb flicker in your head(s) as it did in mine.

WHEN the relief valve is closed ..all the oil goes through the filter ..and, to date, we see ONLY 3-4 PSID.

BUT when the relief valve is open ..the flow NO LONGER DICTATES the resultant pressure readings since it is not merely changing velocity regardless of the restriction presented to the flow.

That is, the increase in PSID is more or less a resultant expression of the flow differential more than it is of a quote "resistance".

Ugly3 · Apr 8, 2005

I think I agree with what you are saying, however, you have it set up as a cause and effect relationship and I don't see it that way.

Seems to me it is the temp of the oil that allows the bypass to close in about a mile of operation. The temp of the oil (and the resulant viscosity reduction) causes both the oil pump releif valve to close and the differential pressure in the filter to reduce to below bypass levels.

My bet is that if you ran 15 miles down the road (full operating temp) and shut the van off for 15 minutes you would find on restart that it takes less than 20 seconds for the filter to get off bypass.

And by the way, your proving grounds are better than DC, GM, and FMC put together.

JohnBrowning · Apr 8, 2005

Guys you are way off thinking that multiviscosity oils are not compressable!!!Multiviscosity oils are not newtonian and can not be counted on to transmit force with out compression! Their is a reason that multiviscosity oils are not used in hydralic jacking machinery!!! If multiviscosity oils were not compressable they would not change under EP situation like they do!

427Z06 · Apr 8, 2005

quote:

Originally posted by JohnBrowning:
Guys you are way off thinking that multiviscosity oils are not compressable!!! Multiviscosity oils are not newtonian and can not be counted on to transmit force with out compression!

Just how much compression do you think is taking place at 80 psi?

http://www.chevron.com/prodserv/nafl/powergeneration/content/prodspecs.shtm#hydraulic

http://www.service-pro.com/awhydraulicoils.PDF

Gary Allan · Apr 9, 2005

quote:

you have it set up as a cause and effect relationship and I don't see it that way.

Well, I can't see it either ..but I have questions ..and try and rationalize answers ..and stumble around a bit until someone whacks me in the head.

This could be a tempest in a teapot ..and I'm merely perceverating on nothing..

quote:

My bet is that if you ran 15 miles down the road (full operating temp) and shut the van off for 15 minutes you would find on restart that it takes less than 20 seconds for the filter to get off bypass.

Aside from when the peak pressure hit 82 on that cool morning ..the PSID has never been any higher than 3-4 PSID. In rapid upswings (revving the engine)..the engine side of the filter reacts first...the tail waging the dog so to speak.

quote:

And by the way, your proving grounds are better than DC, GM, and FMC put together.

Well, I dunno about better...but you'll probably get more information out of it..

quote:

There is a reason that multiviscosity oils are not used in hydralic jacking machinery!!!

Sure ..you don't need it. What you can't do is use hydraulic fluid as a motor oil. I would think that either would be pretty impervious to compression unless aerated. I would think that either could successfully be used for power transmission in an appropriately designed device.

Naturally, mine is a simplistic view here ..so I'm surely up for an education.

Ugly3 · Apr 14, 2005

Gary, filter in bypass yet? How many miles? Update!

Winston · Apr 15, 2005

The PSID across the filter has nothing to do with anything except the PSID accross the filter. It doesn't matter if the pump bypass is open or closed. It doesn't matter what is happening downstream of the filter either. It doesn't matter if the upstream pressure is 80psi or 20 psi. The only thing that affects the DP reading across the filter is the filter media and the oil filter bypass valve.

So, thinking about what is happening in that filter canister upon start up. It is full of cold oil. Then the flow from the pump tries to push oil through the filter, but the highly viscous cold oil has a difficult time getting through the media. Even 12psi is not enough to push all that oil through the filter. So, the bypass filter opens. Now the oil immediately starts to heat up due to the action of the gears in the oil pump. So, the oil in the filter media begins to heat up, slowly reducing the pressure drop accross the media until about 3-4 minutes have passed and then the DP across the media is back to 4psi.

Ugly3 · Apr 15, 2005

Winston - Now the oil immediately starts to heat up due to the action of the gears in the oil pump.

I can't picture the oil pump generating that kind of heat.

Gary Allan · Apr 15, 2005

Well, Winston ....you seem to be a highly qualified individual. Can you share some of keen insight here? We are, after all, here to learn. You appear to have a great deal of conviction and authoratative tone in your posts. You are probably someone we should pay close attention to. If you find us going astray here in this homegrown test, by all means ..please show us the error of our ways and be kind enough to give us a little push in the right direction.

Just to assure that you see where this sorta got started. where the test began and when we discussed some more stuff about it. Now you appear to have already covered this ground before ..but it might be a good read for you anyhow. Feel free to input any corrective advice that might help us out here.

quote:

Gary, filter in bypass yet? How many miles? Update!

The only time I've seen anything close to a bypass threshold was the aforementioned oddity. I'm at around 1400 miles.

I'm swapping out the 15w40 for 20w-50 asap to take advantage of the cooler spring mornings. We may still be in for some sub 40°F startups. As 427Z06 has related to me, this should be just about the thickest oil that anyone could possibly use in these temps. If viscosity itself has any bearing on bypass valve opening ..it should happen then.

427Z06 · Apr 15, 2005

quote:

Originally posted by Winston:
It doesn't matter what is happening downstream of the filter either.

Hmmmm....plug the downstream side of the filter and tell me you won't see 0 PSID across the filter.

Gary Allan · Apr 15, 2005

Winston,

Here's my only hypothesis/query/speculation here (since it's not a theory since I can't yet come up with a pass/fail formula modality for critique).

I'm proposing that there is just an aboslute max flow that the engine can permit @ a given visc @ a given flow rate. As long as that isn't in excess of a resultant PSIG of 82 ..then all is well and the filter evidences 3-4 PSID under all states and conditions.

Ponder upon the following assumed truths (by me)

The filter, and the engine, are constants in terms of resistance presented to the flow (this could be debated somewhat in terms of the engine but I assert that for this demonstration it can be considered a "virtual" constant).

The only reactive and variable compoents are the viscosity and the rate of flow.

The filter always, to this date and in this state of accumulated debris, always shows 3-4 PSID ..except (and we have only one instance of this) when the 82 PSIG limit is seen and the pump relief is open.

It would reason that any collision between the pump flow capability/rate, the relief valve limit, and the viscosity of the oil at that temp is coincidental*. That is, if the relief on the pump was 150 ..then I would still see the exact same 3-4 psid under the exact same conditions.

So, it is obvious to me ..that the opening of the pump relief makes the filter appear to have this elevated resistance and subsequent elevated PSID. It is indifferent to viscosity/flow* and is entirely dependant upon flow divergence via the relief valve.

That is (I propose/offer), that no more flow is possible through the engine @ that visc @ that PSIG and that possibly with no intermediate restriction (the filter media) that no more flow to the engine would occur and that the resultant elevated PSID during this event is merely evidencing (expressing) the amount of shunted flow via the relief valve. That is, with NO FILTER, the PSIG would be uniformly 82 ..but there would be no indication of flow divergence ...hence both flows may or may not be exactly the same.

This is why I question whether the elevated PSIG truly indicates any "real" inhibition to flow.

This is not the main purpose of this exercize ..but merely a "hmmm ...let's take pause and extend a mental tenticle and see if we can explore some of the more intimate little details within this event". It may or may not have any more depth to it than your simple "PSIG is PSIG

" type disposition to it...but I'm not necessarily convinced.

..but hey ... (visions of Blade Runner where the first interviewer just got Leon to twitch) they're just questions, Winston ("and in answer to your query, they're written down for me. They're design to envoke an emotional responce. Shall we continue?")

and btw-

Gary Allan · Apr 15, 2005

darn ..time expired..

Winston

Let me throw this out there and see what your view is on it. This may reduce the entire previous post down to these to thingies here.

Pump relief closed:

100% of the flow goes to the engine. Hence the apparent resistance of the filter(PSID) merely expresses the oil's change in velocity through the media

Pump relief open:

Undertermined flow to the engine. ??? Does the PSID merely express the flow divergence??

Winston · Apr 17, 2005

First of all let me apologize if I P.O.'d anyone. One of my faults is that I talk/and write very directly. (that is how I describe it). I am often told that I am just rude. Such is life.
The other thing is, I realize that I am not always right. When I write down my theories, I am confident that I am right, but I know that I am wrong sometimes and can take it when someone points out that I am wrong. And go ahead and be direct with me I won't be offended.

Thirdly, I think we all get frustrated trying to explain things with words. Often a simple chart, graph, or sketch would clear things up immensely.

I also want to point out that I am very excited to have found this forum. I often wonder about oils a filters and the information here IMHO is outstanding. That data from the Grease Filter study is exactly the data that the oil filter companies don't want to talk about(not that it is a conspiracy, just marketing). And this mini bypass thing that Gary has installed is fascinating. So, I will be careful ant try not to get people too mad at me that I get banned.

Ugly3 · Apr 17, 2005

Gary, have you had the occasion of a warm start after maybe a 15 minute shutdown? Results should be interesting.

Winston · Apr 18, 2005

Gary, you wrote:

quote:

"Pump relief closed:

100% of the flow goes to the engine. Hence the apparent resistance of the filter(PSID) merely expresses the oil's change in velocity through the media.

(Finally figured out how that quote button works.)

PSID is affected by the velocity through the media(flow) So, Yes.

quote:

Pump relief open:

Undertermined flow to the engine. ??? Does the PSID merely express the flow divergence??

I do not think so. I reread your hose analogy and the other more recent post. I still do not think there is a correlation between the pump bypass being open and the DP accross the filter. The DP is the resistance to flow through the oil filter canister. The DP varies due to Flow, Viscosity, and Filter Loading - Only. When the oil is very thick (cold - high viscosity) there is a lot of resistance to flow in the engine and the filter, so upon cold startup the positive displacement oil pump tries to push X gpm through the engine. The resistance from the engine and oil filter is higher than 82 psi so the pump bypass opens. So at this point we might have 0.25X gpm going through the pump bypass straight back to the oil pan and 0.75X gpm going through the filter and engine. At this time the resistance to flow across the filter is also higher than the 12psi bypass pressure of the oil filter relief valve. So the pressure reading is 82, 70. As the oil heats up, the resistance to flow through the engine and filter begins to decrease. So, the oil pump bypass closes a bit more. Now the flow through the pump bypass is about 0.15X and the flow through then engine is 0.85X. The resistance throught the filter housing is dropping quickly (down to 10psi even at the higher flow rate) but now the resistance through the engine is up to 72psi due to the higher flow rate. Thus the readings are PIN=82 and POUT=72. This continues through the first four readings as the pump bypass valve slowly closes. Once the engine+filter resistance drops down below 82psi the the pump bypass becomes fully closed and X gpm is once again flowing through the engine.

Let me define the following.
FByp = Flow through pump bypass to oil pan in Percent %
Feng = FLow through engine in percent %
Vis = Oil viscosity (ssu)
T = Oil temp in Fahrenheit.

Pin, Pout, Fbyp, Feng, Vis, T
82,70,35%,65%,5500,40
82,72,30%,70%,3800,50
82,74,20%,80%,3000,55
82,76,10%,90%,2500,60
80,76,0%,100%,1600,70

FYI at 120 deg F 30wt oil is about 350 ssu.

What do you think? That was for straight 30 weight oil. My oil visc vs temp chart only shows ssu. I was surprised to see how a small temp change made such a dramatic change in viscosity.

Ugly3 · Apr 18, 2005

quote:

Originally posted by Winston:
Hey, Ugly3. I reread some of the previous posts and now I see you are online. I completely agree with you regarding the 15 min restart scenario. I would even bet that the DP would be at 4psi immediately upon startup.

What do you think might be the source of heat to cause the viscosity to drop so quickly upon cold start up? (assuming you agree that the viscosity is changing.)

My guess is that the major source of heat is the combustion heat left on the cylinder walls and the heat coming from the exhaust valves.

Gary Allan · Apr 18, 2005

well, that's some decent work you did there. Keep in mind that I'm challenged on integration of complex text (a crippling afliction and I'm only half joking). You share the opinion of consensus here and although I'm still not fully satisfied with it ..I don't dispute it.

I'm unable to construct a model that demonstrates the filter increasing in apparent resistance due to flow divergence. I mean it doesn't reason that the filter can maintain 3-4 PSID in all circumstances when the relief in the pump is closed ..regardless of viscosity ..yet represents a 3X resistance when the relief is open. This cannot be a function of the filter's true resistance ..if you see what I mean. So, I can't explain what I'm looking for/at ..but it's not been fully explained in any pony terms I can integrate yet.

let me prop up my assertions based on my confusion

We dropped the 15w40 and put in 20w-50 ..subjected it to a 32°F overnight parking ..and started it up in 41°F ambient. Here's what I got at around 30-40 seconds (IIRC-I'll check my notes).

The 20w-50 is surely heavier at all temps than the 15w40 ...so heavy in fact that the 3/8"x 36" lines became a integral component in the circuit. That is, the pump was in relief ..yet due to the upstream resistance of the lines ..my PSID (which did btw start out @ 12 PSID = 72/60) is reduced to about 8 PSID. I revved the engine liberally ..yet I could not attain anything over 80 psi ..and within a very short amount of time ..my PSID was normalized at the typical 3-4 PSID.

yet the 50 weight had to be heavier than the 40 weight for several minutes after startup.

Side note: I was unable to repeat the pump relief event with the 15w40 in spite of even colder over night temps. This leads me to believe that there is something to "new" oil that quickly vanishes in a very few miles (a few hundred). I haven't got a clue what it would be ..

btw- my oil temp guage starts @ 60°F ..but doesn't come off of that for at least 5 miles (at the temps it started at). Naturally this will change with overnight temps that fall in the 70's in a few weeks.

[ April 18, 2005, 10:29 PM: Message edited by: Gary Allan ]

Winston · Apr 18, 2005

Now, back to the issues.

427Z06 wrote: Hmmmm....plug the downstream side of the filter and tell me you won't see 0 PSID across the filter.

Yes, of course that is true. What I was trying to say with my little rude rant about filter DP(Differential Pressure = POUT-PIN) is that the filter is just one component in the lube oil system and all it sees is oil coming from the upstream side and it provides a resistance to that flow which varies due to viscosity, flow, and filter loading. That resistance is measured as DP. (assuming the bypass valve is closed)

When talking about this stuff it is important that we all are seeing the same flow diagram in our heads. Fram has a pretty good one at:
http://www.fram.com/tech/EngineOilFiltering.pdf

When I talk about stuff I am imagining the "Full flow lube oil system with spin on filter."

Ugly3 wrote: "I can't picture the oil pump generating that kind of heat." Honestly, I feel that item is the weakest point of my theory. It was the only way I could explain why the filter DP dropped so quickly after startup. Only three things affect DP (flow, viscosity and filter loading). Flow is inversly proportional to the DP and I am sure that flow is not decresing in those first few minutes during startup. I don't think that filter loading is changing either(unless a bunch of crud is being washed off the filter during the time the bypass is open). So that leaves viscosity, which varies due to temperature. So, I surmised the source of heat could be the pump.

Gary, I love your posts (I really love that filter pressure set-up on your car) but, I am having trouble understanding your last two posts. Don't bother trying to explain them I just need more time to reread them. However, I need to get some work done today so I will reply later.

Winston · Apr 18, 2005

Hey, Ugly3. I reread some of the previous posts and now I see you are online. I completely agree with you regarding the 15 min restart scenario. I would even bet that the DP would be at 4psi immediately upon startup.

What do you think might be the source of heat to cause the viscosity to drop so quickly upon cold start up? (assuming you agree that the viscosity is changing.)

Ugly3 · Apr 21, 2005

Gary Allen,

I read your post in another thread that you are changing to xw20 for the summer. I can picture it, the Van is on the drive, sees you coming with the drain pan and starts shivering, "what is he going to put in me now?".

Mini-update bypass test

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