How critical is the bypass setting?

[Ken2]

quote:

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I see over 30 pounds difference in oil pressure very rapidly just pulling away from a stop light from idle to around 2700 RPM. It hard for me to believe that 10 or 16 pound "rated" oil filter bypass spring is closed. Without even considering the pressures differential that take place in the filter element itself.

---

The differential pressure across the filter element is the only thing the filter bypass valve sees. It only senses the difference between the oil pressure entering the filter and the oil pressure exiting the filter. The absolute oil pressure means nothing to the filter bypass. The bypass is really measuring psid...pounds per square inch differential.


Ken

 

[427Z06]

Lot of good points made above. I think Hirev is correct when he's states that on most engines, the filter enters bypass mode roughly around 3000 rpm.

Here's some data to support that statement:

http://www.shoclub.com/lubrication-oil/lubrication-oilpart1.htm

If the average positive displacement pump's output is near linear at roughly 2 GPM per 1000 rpm, by 3000 rpm were talking 6 GPM and I believe there is no way the tiny filters they're specing now can flow that much oil without going into bypass. Of course, all the above will vary depending on engine size and design.

 

[Gary Allan]

If the pressure isn't surging (like Hirevs) or elevating, I don't think that it is. The vast majority of the engines that I see with gauges have the exact same type of oil indications that I do. 4 different and briefly seperated levels ..two hot ..two cold ..both at idle and at road speed. On my high volume ..I was running Chevy filters before I went to the Cummins threads for the Amsoil setup. The Chevy filter has no bypass. I saw the exact same 58 lbs at anything off idle ..the same 42 at hot idle.


It would reason ..that any linear upramp in oil volume would increase any differential across the filter media ..or any downstream "load" proportionally. Yet we rarely see this in ANY automobile. Aside from a hiper setup ..when do you see linear oil pressure increases??

 

[427Z06]

quote:

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Originally posted by Gary Allan:
If the pressure isn't surging (like Hirevs) or elevating, I don't think that it is. The vast majority of the engines that I see with gauges have the exact same type of oil indications that I do. 4 different and briefly seperated levels ..two hot ..two cold ..both at idle and at road speed. On my high volume ..I was running Chevy filters before I went to the Cummins threads for the Amsoil setup. The Chevy filter has no bypass. I saw the exact same 58 lbs at anything off idle ..the same 42 at hot idle.


It would reason ..that any linear upramp in oil volume would increase any differential across the filter media ..or any downstream "load" proportionally. Yet we rarely see this in ANY automobile. Aside from a hiper setup ..when do you see linear oil pressure increases??

---

Huh? Chop off the high and low ends and my oil pressure gauges read very similar to that SHO link I posted. The high end can be explained by the bypass valve in the pump itself. The low end is probably due to leakages in the pump itself.

 

[Hirev]

Gary Allan your right in that most Chevys don't use a oil filter with a bypass.

As you most likely know Chevys use a block mounted oil filter bypass.

Some people here should at least go pick up a Chevy block mounted oil filter bypass in a boneyard and a Chevy oil filter and have a look for them selfs as to how oil filter bypass works.

They use an external bypass valve so you can see how the setup works. You can push open the bypass very easy with a pen and the valve opens up with pressure around 12 - 15 pounds. Oil will take the path of least resistance every time. Some goes through the filter and some goes around it.

According to Bill Jenkins even a full size bypass style oil filter did not even filter 50% of the oil cycle through it at higher pressure. Just imagine how the little filters do on many of todays cars.

 

[Gary Allan]

quote:

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very similar to that SHO link I posted

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This what you mean

With the engine loafing the filter by passes no oil, so it filters 100% of the oil. If we empty the oil pan once every 17.7 seconds, we will do it 20 times in 6 minutes or 8 miles. Assuming we have a good air filter, so we do not add a lot more dirt, after 6 minutes of easy driving our oil should be almost virgin; down to say - 10 microns.

Still with me? What if I have need for speed? The engine pumps 2 GPM for each 1000 rpm. Assume for this example the filter can only flow 6 GPM with the by-pass closed so the by pass will have to open. If one half the oil entering the filter evades the cleaning process and takes the bypass. The other half of the oil will get cleaned at 90%.

quote:

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As you most likely know Chevys use a block mounted oil filter bypass.

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Yes, I know this ..but I wasn't using Chevy filters on a Chevy engine ...it was my 4.0 jeep engine using a Permacool mount. No oil ever got passed the media ..no difference in pressure was even present. It actually never occured to me that using the larger Chevy filters (they're bigger than the Ford style) that I didn't have this feature til I was lurking around here and someone was looking for a chevy thread with a bypass ..they don't exist it appears. It was then I realized that I didn't have one while running this setup.

quote:

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According to Bill Jenkins even a full size bypass style oil filter did not even filter 50% of the oil cycle through it at higher pressure

---

Grumpy was a genious ..no two ways about it ..but I think that I'd have to actually see his words in print to take them in context. Was he speaking as "Grumpy" the reknowned engine builder in terms of a racing application with a heavily dead headed pump with rapid and abrubt surges in oil flow using racing oil

or did he say this as a mechanical engineer in regard to common hokey-pokey passenger cars using 20w-20???


Anyway ...I'm not convinced ...but I won't argue the point anymore either. That is, you both may very well be right ..but I'm not hearing what I need to be convinced.

If this assertion is true ...we should all be using the filter media with the highest trap ratio since we're playing Russian roulette 50% (25%-20%-40% who knows

= but over 100,000 miles ..once is 100% success for the large particle) of our operation time. That is the chances of larger particles getting past the filter are heavily weighted in the particles favor. That is, ANY filter is a mere crap shoot at best of saving your engine. I just have a hard time with that.

[ October 31, 2004, 01:51 AM: Message edited by: Gary Allan ]

 

[427Z06]

quote:

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Originally posted by Gary Allan:

quote:

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vry similar to that SHO link I posted

---

This what you mean

With the engine loafing the filter by passes no oil, so it filters 100% of the oil. If we empty the oil pan once every 17.7 seconds, we will do it 20 times in 6 minutes or 8 miles. Assuming we have a good air filter, so we do not add a lot more dirt, after 6 minutes of easy driving our oil should be almost virgin; down to say - 10 microns.

---

And your point is?

 

[Gary Allan]

I just added that for reference, my tape and paste was more to do with:

quote:

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Assume for this example the filter can only flow 6 GPM with the by-pass closed so the by pass will have to open.

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This could have just as easily said, "Assume for all examples that a filter can always flow 25 gallons of oil with the bypass closed

.or..

"Assume that the filter has no tolerance for more than a few oz. of oil before opening the bypass.


Where did this figure get pulled from?? Fram? Purolator? Wix, Baldwin, Champion? K&N?

As I said, you both may very well be totally correct ...and that's a scary thought.

Sorry! When you shatter one of my paradigms ...you have to connect the dots for me to see it. I'm blinded by my belief

 

[Filter guy]

Well this certainly is an interesting discussion.

You can go to the supertec thread and read my credentials.

Ken is right, the oil filter itself only senses differential pressures.

Some in here are getting their shorts in a wad over engine oil pressure and the output of the oil pump.

There is a pressure regulating valve in the oil pump. This is why the engine, whether it revs at 6,000 rpm or 2,000 rpm maintains near constant oil pressure.

The regulating valve at the oil pump usually keeps the oil "flow" pressure rate to somewhere between 40-50psi.

So if the filter is seeing 45 psi oil flow, the filter by-pass or relief valve ( check valve as filter engineers call it) will open or close based on the differential pressure across the element.

As for the original question..it is the ENGINE manufacturers who determine the best filter relief valve settings, not the filter company. There is a reason for that based on the tolerances and minimum flow rates from the filter needed in conjunction with the setting for the system oil pressure regulation.

So it is critical not to monkey with the oil filter by-pass valve settings when determining should I use this filter or that one because of different pressure relief settings. In otherwords, don't use a VW filter ( usually 30-35psi valve) on a Ford ( usually 8-11psi) or vise/versa.

For those who love their guages...try this.
At initial start up, what pressure do you see?

And after driving for a while or at idle sitting in the driveway, do you see the pressure come down and level off?

And why do you think that is..

You might find out that the regulating valve at the oil pump is maintianing constant oil pressure. So when the relief valve at the filter senses the correct differential across the element it closes and the regulatiing valve at the oil pump adjusts, then your oil flow pressure becomes constant.

That higher pressure at start up is due to no oil coming from the engine to the sump, so the regulating valve allows a higher volume of oil to flow to the engine. Almost immediately there is oil flowing back and the regulating valve at the pump adjusts. But it still needs to send a little more flow because the filters by-pass valve is creating restriction in the system. Once it shuts off, the oil pump regulating valve senses the difference and adjusts. At which point the oil pressure guage remains near constant. Minor changes due to revs increasing or slowing is just the oil pump regulating valve sensing what is needed based on your lead foot. At this point in time the filters by-pass valve is uneffected unless there are pressure spikes. Even then those are minimal and last micro seconds.

To think that the oil filters pressure relief valve is open all the time if false. To claim it is open while one is driving along for most city/highway driving is also false.

Of course the disclaimer is how much contaminant has plugged the filter. Generally filter companies have tested used filters and there is anywhere from 40-80% of the filter element contaminant capacity unused. So for normal driving city/highway driving you won't encounter the filter relief or by-pass valve opening up during the operation of the vehicle other than at startup.

 

[427Z06]

Filter guy, your credentials mean nothing to me after reading what you posted. Some of it is accurate. Some of it is pure bunk. You stated you were in sales, marketing and training, which explains why you don't have a grasp of some the basic laws of physics. I could go through, and point out all the inaccuracies, but I know I'd just be wasting my time, since you sound like the type who thinks he's the only one who knows anything about automotive engine filtration.

But hey, one of the things this board is about is expressing one's opinions and you expressed yours.

Good day to you sir.

 

[XS650]

quote:

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Originally posted by 427Z06:
Filter guy, your credentials mean nothing to me after reading what you posted. Some of it is accurate. Some of it is pure bunk.

---

You called that one right.

 

[Filter guy]

quote:

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Originally posted by 427Z06:
Filter guy, your credentials mean nothing to me after reading what you posted. Some of it is accurate. Some of it is pure bunk. You stated you were in sales, marketing and training, which explains why you don't have a grasp of some the basic laws of physics. I could go through, and point out all the inaccuracies, but I know I'd just be wasting my time, since you sound like the type who thinks he's the only one who knows anything about automotive engine filtration.

But hey, one of the things this board is about is expressing one's opinions and you expressed yours.

Good day to you sir.

---

Thanx...I've only been around filter engineers, automotive companies, oil companies, and other filter manufacturers for 20 odd years. So your right....

Maybe at some point in time you might try to arrainge a tour of a filter manufacturer for yourself and ask any question you want of the engineers.

 

[XS650]

quote:

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Originally posted by Filter guy:
Thanx...I've only been around filter engineers, automotive companies, oil companies, and other filter manufacturers for 20 odd years. So your right....

---

Claiming casual relationships as credentials does not compensate for making nonsensical statements.

 

[JDP]

Filter guy!

quote:

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You might find out that the regulating valve at the oil pump is maintianing constant oil pressure. So when the relief valve at the filter senses the correct differential across the element it closes and the regulatiing valve at the oil pump adjusts, then your oil flow pressure becomes constant.

---

Would you please explain how the regulating valve in the oil pump does this.

quote:

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That higher pressure at start up is due to no oil coming from the engine to the sump, so the regulating valve allows a higher volume of oil to flow to the engine.

---

once again please explain.

quote:

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Almost immediately there is oil flowing back and the regulating valve at the pump adjusts. But it still needs to send a little more flow because the filters by-pass valve is creating restriction in the system. Once it shuts off, the oil pump regulating valve senses the difference and adjusts. At which point the oil pressure guage remains near constant.

---

Please explain how this works.

JDP

 

[427Z06]

quote:

---

Originally posted by Gary Allan:

Yes, I know this ..but I wasn't using Chevy filters on a Chevy engine ...it was my 4.0 jeep engine using a Permacool mount. No oil ever got passed the media ..no difference in pressure was even present. It actually never occured to me that using the larger Chevy filters (they're bigger than the Ford style) that I didn't have this feature til I was lurking around here and someone was looking for a chevy thread with a bypass ..they don't exist it appears. It was then I realized that I didn't have one while running this setup.

---

Gary, I think we're close to agreeing, it's just hard to get our points across in small posts.

Let me ask you this. What filters were you using on your permacool mount? A pair of PF25s?

 

[427Z06]

quote:

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Originally posted by Filter guy:
Maybe at some point in time you might try to arrainge a tour of a filter manufacturer for yourself and ask any question you want of the engineers.

---

As an engineer with 24+ years experience in the military defense and now the automotive industry, I can talk to the engine designers any day of the week.

 

[Ken2]

quote:

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That higher pressure at start up is due to no oil coming from the engine to the sump, so the regulating valve allows a higher volume of oil to flow to the engine. Almost immediately there is oil flowing back and the regulating valve at the pump adjusts. But it still needs to send a little more flow because the filters by-pass valve is creating restriction in the system. Once it shuts off, the oil pump regulating valve senses the difference and adjusts. At which point the oil pressure guage remains near constant. Minor changes due to revs increasing or slowing is just the oil pump regulating valve sensing what is needed based on your lead foot. At this point in time the filters by-pass valve is uneffected unless there are pressure spikes. Even then those are minimal and last micro seconds.

---

What!

The oil pressure regulating valve in the oil pump housing is a very simple device. It has oil pump outlet pressure working against one side of it and a spring working against the other side. When the oil pump pressure exceeds the spring force, the valve begins to open. More pressure causes the valve to open more. Less pressure causes the valve to open less, or go closed. The oil pressure is higher when starting because the cold oil has higher resistance to flow. Hot oil and idle speed is the lowest oil pressure I see on the gauge in my truck. At about 1800 rpm my oil pressure gauge is as high as it gets, and the pressure regulating valve just opens more as the engine & pump turn faster and put out more oil.

How does the filter and its bypass valve relate to all this? Simply as one more point of resistance to flow. More resistance with cold oil, less with hot oil, proportionally more resistance with more flow. All this is part of the lube system design. The engine design engineer has all this figured in when he spec'd the particular oil filter. The bypass valve in the filter just puts a ceiling on the resistance in the filter. A filter with an 8-11 psid bypass will not have more than 11 psi pressure resistance. The resistance will be much lower with hot oil and a clean element. The bypass valve does not create resistance...it limits resistance to flow. Again, all this is in the design from the engine engineer.

Does the oil filter get significantly dirty and cause the bypass valve to open more often? If that was the case, I'd expect the insolubles in an oil analysis to increase greatly at higher mileage. I haven't seen that. That leads me to believe that the oil filter does not get clogged in normal mileage...10,000 mile oil change interval on my truck.


Ken

[ October 31, 2004, 06:12 PM: Message edited by: Ken2 ]

 

[Ugly3]

Article On Oil Pumps & Releif Valves.

This may help clear up how the oil pump releif valve works.

 

[427Z06]

Ken2, my compliments, very clear and concise post, something I didn't have the patience to do.

Overall, I agree with you but I have to make a couple points. Remember that the insolubles in an UOA are submicronic. And, if you have something like a 5w40 in your truck, and you start it up freezing cold weather and within a couple minutes run it up to highway speeds, I'll bet my left nut that some of that oil is bypassing the filter media.

Other than that, nice job.

 

[JDP]

Thank you Ken2 and 427Z06

Thanks for the clarifications. I didn’t have the time or patience to write out things the way you did either, hence my questions in hopes that filter guy would come to his senses and see where the jiberish was in what he wrote.

Oh well, his post did finally get me to join with a membership.

No doubt the 0W30 I use in the winter bypasses in the filter when I first start up in the morning too.

Ugly3 - thanks for the link (somehow it bothers me to write that name). There are excellent explanations for the engine lube system on that page!!!

Does any one know of information on the cracking pressures versus full flow pressures for any of the pressure regulators used in the engine lube pumps? I have wondered for a long time about the amount of oil being bypassed at the regulator when a new engine is idling. Guess maybe I’ll have to set up some kind of a test using a common engine oil pump.

Thanks guys!!!!

JDP