Ecore Experience

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Still wondering about this..

If media "restricts" the flow of oil through an opening the size of the outlet..just think how restrictive the same media is that is restricting flow of oil through those itty bitty holes in the metal center tube.
 
Gary,

When you say pump relief, I assume you are talking about the oil pump pressure regulator valve that controls system oil pressure. Whereas the oil filter bypass valve is the one blocked on the subject engine.

It would seem to me that relative pressure drops across filter and engine would be fairly constant regardless of the state of the oil pump pressure regulator valve. Therefore, even in the scenario where the filter bypass is blocked and the oil pump regulator valve is stuck closed, system pressure would need to reach some huge number (hundreds of PSI) to create 70+ lbs. of differential pressure across the filter since most of the pressure drop would still be across the rest of the engine (bearing clearances, oil passages, etc.)..
 
Brian. You're assuming the system has pressure downsteam from the filter. This isn't the case at startup. At startup, until all the system pressures equalize, the differential pressure across the filter is much higher than during normal operation.

This is likely when bowties filter was damaged.
 
Let's take the following cold start scenario. Let’s assume the filter bypass is blocked. And let's assume the filter ADBV is working and the filter is full of oil. Let’s also assume that the oil passages are empty. When the engine starts, the positive displacement pump provides whatever pressure is necessary to provide a path for its flow. If that pressure is less than the regulator valve pressure, all the flow goes through the filter and into the engine.

It’s been suggested that something like the following occurs. When the engine is started, the oil pressure builds for the first few seconds from 0 to 70+ lbs. Even as the 70+ lbs is reached, all of the 70+ lbs. of pressure drop remains across the filter. At some point (after 70+ lbs. of pressure is reached), the pressure drop across the engine rises and the pressure across the filter drops, until the system is stabilized with 3-5 lbs. across the filter and the rest of the 70+ lbs. across the engine. If this is what occurs, the filter will see 70+ lbs. of differential pressure. But I’m not buying it.

This is what I think happens. When the engine is started, the system pressure builds for the first few seconds from 0 to 70+ lbs. That is, as the passages fill during the first few seconds, the system pressure is rising up to 70+ lbs. During the system “filling” process, the drop across the filter rises rapidly to 10 or perhaps even 20 lbs, and then falls as the passages are filled for those few seconds. As the passages fill, both oil flow and differential pressure across the filter drop as the system pressure rises to 70+ lbs. By the time the 70+ lbs. is reached, the passages are full, with a few lbs. of pressure drop across the filter and the remaining part of the 70+ lbs. dropped across the rest of the engine. In this case the oil filter never sees anywhere near 70 lbs. of differential pressure.
 
quote:
Originally posted by Brian Barnhart:
Gary,

When you say pump relief, I assume you are talking about the oil pump pressure regulator valve that controls system oil pressure. Whereas the oil filter bypass valve is the one blocked on the subject engine.

It would seem to me that relative pressure drops across filter and engine would be fairly constant regardless of the state of the oil pump pressure regulator valve. Therefore, even in the scenario where the filter bypass is blocked and the oil pump regulator valve is stuck closed, system pressure would need to reach some huge number (hundreds of PSI) to create 70+ lbs. of differential pressure across the filter since most of the pressure drop would still be across the rest of the engine (bearing clearances, oil passages, etc.)..
Click to expand...
Let's try it this way. Can we agree that "the engine is the engine"? Can we also agree that, aside from some minor issues ..that the pressure drop across the engine is directly related to the flow through it (assuming the same visc oil)??

So ..if 1gpm at let's say idle ..gives us 50lbs ...2gpm will give us 100lbs???

Now according to this ..the filter is next to nothing. Dwarft by the incredible resistance of the engine. You got that part ..I get that part.

Now, and this is ONLY for the sake of demonstratioin, just so I don't have to construct the REAL scenario,.....

..assume the relief is open ...it's @100.0001 psi and that 1 gpm is passing through the relief (assume that this threshold has been reached - the relief is set @100.00005)

So NOW we have 100.0001 psi applied ....1 gpm going through the relief ..and one gpm going through the filter and through the engine.

How much backpressure does the engine generate @1gpm??? 50lbs. This is the upstream pressure seen by the engine ..this is the downstream pressure seen by the filter.

So we have 50 lbs of backpressure from the engine and 100.0001psi applied. It is the pressure seen by both the upside of the filter ..and the pressure relief.

So the filter sees 100psi on the supply side ..and 50 psi on the demand side. It only sees 1gpm of flow.

So ..we see 50.001 PSID @ 1gpm flow to the engine.

Now blip the engine up to 6k and instantly apply 8 gpm into the "chamber" that exists between the upside of the media and the relief.

This is not a perfect example ..it's got it's flaws and needs a "lil help" ..and is not necessarily shared by all. It does satisfy my observations.

So ..you could say I watched something approaching the speed of a snail ...and then back spec'd Goldberg's theory of how I was related to snails.

[ June 23, 2006, 12:04 PM: Message edited by: Gary Allan ]
 
quote:
Originally posted by Filter guy:
Still wondering about this..

If media "restricts" the flow of oil through an opening the size of the outlet..just think how restrictive the same media is that is restricting flow of oil through those itty bitty holes in the metal center tube.
Click to expand...
Get a 2"x4"x8' piece of wood. Take your favorite gun and shoot through the thinner cross section. Next, shoot lengthwise from end-to-end. Which bullet makes it through the wood?
 
quote:
Originally posted by LT4 Vette:
Would engine damage still occured if he used 5w30 oil instead of 20w50 ???
Click to expand...
I have a feeling we'll never know.
cool.gif
 
quote:
Originally posted by Brian Barnhart:
Let's take the following cold start scenario. Let’s assume the filter bypass is blocked. And let's assume the filter ADBV is working and the filter is full of oil. Let’s also assume that the oil passages are empty. When the engine starts, the positive displacement pump provides whatever pressure is necessary to provide a path for its flow. If that pressure is less than the regulator valve pressure, all the flow goes through the filter and into the engine.

It’s been suggested that something like the following occurs. When the engine is started, the oil pressure builds for the first few seconds from 0 to 70+ lbs. Even as the 70+ lbs is reached, all of the 70+ lbs. of pressure drop remains across the filter. At some point (after 70+ lbs. of pressure is reached), the pressure drop across the engine rises and the pressure across the filter drops, until the system is stabilized with 3-5 lbs. across the filter and the rest of the 70+ lbs. across the engine. If this is what occurs, the filter will see 70+ lbs. of differential pressure. But I’m not buying it.

This is what I think happens. When the engine is started, the system pressure builds for the first few seconds from 0 to 70+ lbs. That is, as the passages fill during the first few seconds, the system pressure is rising up to 70+ lbs. During the system “filling” process, the drop across the filter rises rapidly to 10 or perhaps even 20 lbs, and then falls as the passages are filled for those few seconds. As the passages fill, both oil flow and differential pressure across the filter drop as the system pressure rises to 70+ lbs. By the time the 70+ lbs. is reached, the passages are full, with a few lbs. of pressure drop across the filter and the remaining part of the 70+ lbs. dropped across the rest of the engine. In this case the oil filter never sees anywhere near 70 lbs. of differential pressure.
Click to expand...
We agree on how the system acts initially, we just don't agree on what the differential pressure might have been. The point is the though, initial differential pressure across the filter is higher than normal until the system pressures equalize. Much higher. Champion claims it was above 70 psi but I'll admit we don't really know that for sure.

It hardly matters though. Had the bypass circuit been operational, this likely would not have occurred and IMO it's foolish to disable it for all the reasons previously mentioned in this thread. Situations like this are exactly why the system was engineered in the first place.
 
"So the filter sees 100psi on the supply side ..and 50 psi on the demand side. It only sees 1gpm of flow.

So ..we see 50.001 PSID @ 1gpm flow to the engine."

Sorry Gary, this can not happen. I don't know a really good way to explain it.
 
Okay ..this may work better for some.

If you can agree on a near linear model for flow through the engine ..this should send you in the right direction.

Set up a given flow ..and assign it a given pressure. This will be the back pressure of the engine.

Now just assume that the relief is .0001" wc above that pressure.

Now reduce your flow by any amount.

The engine MUST generate less backpressure ..the pressure applied MUST be at +.0001wc that is was before.

Where is that pressure drop realized? If there was no filter there would just be a divergence of flow and an applied pressure. The engine and the impedence of the relief would both see the relief setting.

If there was a bypass valve in the filter ..the pressure drop across it would antenuate at that setting.

The impedence across the filter is (really reaching here for lack of being able to articulate this) a "recipricol" impedence to the impedence of the relief.

In the proportions of the flow division between the relief and the filter ..they both add up to 100% of flow. Their impedence is balanced along the lines of the division of flow. The relief drops 100% of the pressure across it. It is reactive. The other side of the circuit must match (in proportion to flow divisions) that impedence.

The engine ...is just the engine.
 
quote:
Originally posted by Winston:
"So the filter sees 100psi on the supply side ..and 50 psi on the demand side. It only sees 1gpm of flow.

So ..we see 50.001 PSID @ 1gpm flow to the engine."

Sorry Gary, this can not happen. I don't know a really good way to explain it.
Click to expand...
I'm sorry Winston, but it does. You can construct a different model to satisfy things ..but this is what occurs.
 
While this debate goes on..let me toss this out.

A new filter, regardless of filter manufacturer, be it constructed with a metal center tube or not, whether it has cellulose, blended, or synthetic media--will have a pressure drop from about .5 to 2 PSID.

Pete C. can chime in if I am wrong..
 
I can verify that FG. Absolutely. If that was absolutely 100% 24/7 true ...there would never have been a need for any bypass valve to ever be installed on any filter ....and RB would never have generated enough PSID to collapse the center tube.


I can get a brand new filter to achieve 10psid. All I need is very heavy oil to trip the pump relief at any flow rate.
 
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