Does the filter really alter performance?

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Can you complicate the question a little? It depends. Some report more noise at start up ...lingering HLA noise ..etc..etc...but "performance"
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..that would be a stretch.
 
Some will say that larger filters give better flow and more oil capacity, my father swears his Nissan Sentra is running much quieter, smoother and more responsive with a filter nearly 3X bigger filter than the suggested OEM thimble sized filter by Nissan. His oil is now actually being filtered in the media rather than just being bypassed by the bypass valve in the NISSAN thimble. He also added a by-pass filter system too, for him it was a good choice considering the oil sump is only about 2.7 liters or quarts.

Some will also say that more oil capacity is not good when needing fast warmups with lots of short trips, but less frequent and longer trips may be good idea using more oil and larger filter. Keep in mind we have sever winters up here, in the tropical belt it probably wont be a problem.

Cyprs
 
I changed from GM DELCO UPF-44 (their high performance oil filter) to a WIX and got a UOA (use Mobil 1 5W-30 in my 1998 Corvette). No difference, Blackstone Labs told me they rarely see any difference with different oil filters.

Now, my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow. This is why I changed, some people on Corvette Forum say that the UPF-44 and Mobil 1 oil filters, filter too good, at the expense of good oil flow.

As far as size of oil filters, I'm not sure if it makes a difference. Look at this picture of my Corvette Oil Filter verses my 2006 Nissan Murano oil filter, it is small.

[image]http://docthumb0.esnips.com/imageable/thumbnail/cac31285-b771-406d-a9b1-34c54b7a3335/?du=990b3a32-ee21-4a4c-9f13-5af096b24c1c&uu=4f39b70a-30f8-4ac1-96ca-63cc100fe2d8&dt=1178669023000&fu=e3b27402-fad7-46b4-93c9-d979a81a610d[/image]
 
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Originally Posted By: Corvette Owner
...my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow. This is why I changed, some people on Corvette Forum say that the UPF-44 and Mobil 1 oil filters, filter too good, at the expense of good oil flow.

Pardon my ignorance, but aren't you getting the same flow, just at a higher oil pressure?
 
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Some will say that larger filters give better flow and more oil capacity,


In most sensible terms, they give (marginally) "easier" flow (at the same volume) and more oil capacity.
 
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Now, my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow.


Yes, it does. If the sensor was before the filter ..you would always see pump pressure. There would be nothing to alter it.

This is a transitional event and your pump is in relief. No alteration in engine pressure can be seen once it's off of relief ...at least at most sensible oil volumes.

That is, you cannot be seeing 10-15 psi once the pump is out of relief ..and I suspect that YMMV depending on ambient temp.
 
Originally Posted By: tropic
Originally Posted By: Corvette Owner
...my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow. This is why I changed, some people on Corvette Forum say that the UPF-44 and Mobil 1 oil filters, filter too good, at the expense of good oil flow.

Pardon my ignorance, but aren't you getting the same flow, just at a higher oil pressure?


No, the size of my oil lines and "openings" did not change, therefore more pressure equals greater flow. Simplified formula for non-compressable fluid.

Q = K (P)^0.5

Q flow in gpm
P pressure in psi
K factor (refer to the manufacturer's catalog)

Nominal Orifice size (in) / K factor:
1/4" / 1.3 to 1.5
5/16" / 1.8 to 2.0
3/8" / 2.6 to 2.9
7/16" / 4.0 to 4.4
1/2" / 5.3 to 5.8
17/32" / 7.4 to 8.2
5/8" / 11.0 to 11.5
3/4" / 13.5 to 14.5

(Did I mention that I am a Mechanical Engineer?)
 
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Great. Please come up with a model that rationalizes the shunted flow through the relief as it is expressed in PSID. I don't have the moxie to do this. That is, once 100% of the sensible flow is going through the engine, there is virtually no PSID across the media. The PSID must be an expression of the volume being shunted.

That is, once the sensible pump output is at unity with the flow to the engine, there is NO pressure drop across the filter ..only minor elevations in additional developed pressure.

How would one calculate it ..or rather "prove" it?
 
Originally Posted By: tropic
Originally Posted By: Corvette Owner
...my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow. This is why I changed, some people on Corvette Forum say that the UPF-44 and Mobil 1 oil filters, filter too good, at the expense of good oil flow.

Pardon my ignorance, but aren't you getting the same flow, just at a higher oil pressure?


If the oil pressure sensor is AFTER the filter, then an increase of pressure at that point means that the filter has less pressure drop across it - as long as the oil pump is not in relief mode (ie, all the pump's output is going through the filter/engine oil circuit.

Seeing a lower oil pressure after the filter could also mean that the oil pump has gone into relief and the flow volume has decreased accordingly.

I ran the ACDelco Ultraguard UPF-44 on my Vette a few times also, and didn't see any change in oil pressure. Of course, I keep the revs down until the oil warms up some. I saw the same cold idle oil pressure with the UPF-44, WIX/NAPA Gold and Amsoil filters.
 
Originally Posted By: Gary Allan
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Now, my cold oil pressure went up 10-15 psi, and since the Corvette's oil pressure sensor is AFTER the oil filter, this means more oil flow.


Yes, it does. If the sensor was before the filter ..you would always see pump pressure. There would be nothing to alter it.

This is a transitional event and your pump is in relief. No alteration in engine pressure can be seen once it's off of relief ...at least at most sensible oil volumes.

That is, you cannot be seeing 10-15 psi once the pump is out of relief ..and I suspect that YMMV depending on ambient temp.


Define "in relief" ?

Is "YMMV" a typo, if not what does it stand for?

If the oil pressure sensor was BEFORE the filter, you would read higher pressures with a more restricted oil filter. The pressure would vary, it would just "mean" diferent things.
 
Thanks. Perhaps the "AFTER the oil filter" part is significant, eh? I guess I kinda skimmed that even though I quoted it.

OT: I'm a physics/computer science guy, but my brothers are chem E (Navy nuclear propulsion officer) and a biomedical engineer. I have the luxury of forgetting what I learned in college. They don't.
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Define "in relief" ?



Unless the pump is in relief (or leaking internally), there is no appreciable PSID across the filter. Hardly any. I'll venture to say that your hot oil pressure is the same regardless of what filter you use. That clearly indicates a reactive impedance. The pump is only positive displacement when not in relief. It is only in relief that it will have the potential to appear like a normal resistive circuit with pressure "drops". Out of relief ..100% of the sensible flow is going through the engine. In that state, there are absolutely no pressure drops ..but pressure elevations back toward the supply.



So unless you're in relief ..you cannot be seeing lower pressure. Your perception that the filter is doing this is correct.

YMMV= your mileage may vary

(did I mention that I'm a totally undisciplined novice?
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Roger that, I understand what you are saying and it sounds logical and correct. You are correct that my hot oil pressure did not change much, if anything. Now I understand why.

I also enjoyed your "did I mention that I'm a totally undisciplined novice? )" comment, VERY NICE.

But I didn't bring out my "big guns" as by education I am a Mechanical Engineer, but by profession I am a "Rocket Scientist". Retired Navy Civilian now working as a consultant.
 
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I just like humor ..and saw an opportunity to use it
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No, really, I've been trying to find someone to put to paper a rational model where I "run out of steam" in my assembled constructs that were the result of observations in testing above and below pressure readings on filters. We've got some real heavy weights here ..and I haven't been spanked for what I've massaged so far (gosh am I gonna be crushed
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) ..but neither have I been taken to the full modeled "proof" of what I "believe" is true (for lack of that missing element). I don't have that ability.
 
Hmmmm, a un-rounded out theory . . .

What I understood from you, and reasoned, was that the oil pressure in an engine is due to the "most restrictive" element of that engine. This, I reason, is probably the main bearings. So, the "steady state" oil pressure will reflect this pressure.

My reading of "cold oil pressure" increases was the pressure before it reached steady state.

Now, if you run a "test rig" using just an oil filter with a gauge BEFORE and AFTER the filter and do NOT run it closed cycle (allow oil to collect in a bucket), you should see the pressure drop caused by the oil filter. BITOG was "fooling" around with doing this years ago.
 
Yes. Bob did the open bucket test with a motor driven oil pump into an engine. The flaw in the experiment is that he established a baseline upstream pressure standard ..then measured the pressure drop. If, OTOH, he had done all tests at some standard temp AND use the downstream pressure as his baseline, it would have (more or less) assured that the same volume was being processed through the engine regardless of what filter was being tested. He could have then decreased/increased the engine side pressure to see the effects.

I can't factor anything beyond viewing the engine as ONE circuit. It really doesn't matter if it's a complex parallel circuit beyond the gallery or passage from the filter to it. Those various passages will process varied volumes of oil based on design ...but from the view of the filter, it presents itself as one mass restriction.
 
Originally Posted By: Gary Allan

Unless the pump is in relief (or leaking internally), there is no appreciable PSID across the filter. Hardly any. I'll venture to say that your hot oil pressure is the same regardless of what filter you use. That clearly indicates a reactive impedance.


IMO, and based on fluid dynamics, there will always be some level of PSID across a filter is there is flow across the filter ... regardless if the filter has any back pressure on it or not. A PSID of 10 can be achieved by putting 10 psi on the inlet with 0 psi on the outlet, or by putting 210 psi on the inlet with 200 psi on the outlet ... or any similar combination. The driving force that makes the oil flow is the 10 psi in these examples.

In a case where the oil viscosity is constant, the PSID will go from 0 to some max right along with the developed pump pressure going from 0 to it's relief pressure. The max PSID across the filter will occur at the same time the oil pump goes into relief mode ... as that point is the highest possible oil pressure the pump can supply to the system.

When you say "Unless the pump is in relief (or leaking internally), there is no appreciable PSID across the filter.", there needs to be specific qualifiers associated with that statement. There is always some level of pressure drop across the filter if there is flow through it. That level depends on the volume and viscosity of the flow. If the volume is high and viscosity high (redline with -20 deg F oil - ouch), then the PSID is max ... if the volume is low and viscosity low (hot oil at idle), then the PSID is small and negligible like Gary has indicated. There is a HUGE spectrum of operating conditions going on, so any broad statement need to have the qualifier nailed to it.


Originally Posted By: Gary Allan
The pump is only positive displacement when not in relief.


Well actually, the pump is a positive displacement device regardless if it's in relief or not. The relief valve is on the output side of the pump. When in relief, then a portion of that volume gets spit back into the sump and doesn't get send down stream to the filter/engine circuit.

Originally Posted By: Gary Allan
It is only in relief that it will have the potential to appear like a normal resistive circuit with pressure "drops". Out of relief ..100% of the sensible flow is going through the engine. In that state, there are absolutely no pressure drops ..but pressure elevations back toward the supply.


Not sure I follow ya here - I think it's word semantics and writing style getting in the way. IMO, any time there is flow through the filter/engine circuit there is a pressure drop happening ... both across the filter and across the engine's circuit. Think of the engine's complex oiling circuit as one fixed resistor, which it really is.

Let's say you have a straight section of tubing 10 ft long, and you put 20 psi on one end and 0 psi (vent to ATM) on the other end, then there is a pressure gradient going down the pipe. The pressure is not 20 psi a 1/2" from the vent. If you could put pressure gauges at every 1 foot along the tube, you would see the pressure drop as you went from the 20 psi end to the 0 psi end. Therefore, this 10 ft section of tubing has an effective 20 PSID associated with the flowrate going through it. It took 20 psi to move that fluid volume (ie, GPM) through the tube.

The same is going on in an engine's oiling system. The oil pump supplies say 60 psi to the inlet of the system (inlet to the filter), and the system ultimately vents to ATM (the sump). All along the system as oil flow through it, there are pressure drops that will all add up to 60 psi. Some pressure is lost at the filter, some at each bearing in the engine, etc. The pressure is NOT the same everywhere in the system as there is flowrate through it. Only if you blocked the vent to the system and stopped the flow, then all points in the system would equalize to the same pressure.
 
Originally Posted By: Corvette Owner
Now, if you run a "test rig" using just an oil filter with a gauge BEFORE and AFTER the filter and do NOT run it closed cycle (allow oil to collect in a bucket), you should see the pressure drop caused by the oil filter. BITOG was "fooling" around with doing this years ago.


Like I said above, I think any time you have flow through the filter you will have some level of pressure drop totally dependant on the flow volume, fluid viscosity and resistance factor of the media. That is fluid dynamics ... how can you have flow through something resistive to flow without a pressure drop? ... another "cold fusion" case? LOL. Even a straight section of tubing has a resistance factor and pressure drop.

PSID is a PSID ... it doesn't matter if it's obtained with the filter outlet at ATM pressure (0 psi) or with the outlet with lots of back pressure on it. In other words, you can obtain 10 PSID by:

1) Filter inlet at 10 psi, filter outlet at 0 psi (vent to ATM)
2) Filter inlet at 60 psi, filter outlet at 50 psi (ie, engine's oil circuit "back pressure").
3)Filter inlet at 150 psi, filter outlet at 140 psi (an even more resistive engine oiling circuit and more back pressure to the filter).
 
I did a google and it looks like only 2 psi pressure drop can be attributed to the oil filter. This is relatively insignificant when compared to the 40-60 psi of a running engine. I think this is the point he was making.
 
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