Where is the Proof?

[Rob T]

If a larger filter has lower pressure, I think someone said this earlier, wouldn't the filter take longer to go into bypass, thus starving your enginge of oil at startup?
Isn't flow more important than filtering?
Even some oil, even unfiltered oil, is better than no oil.
Don't most filters or engines run in bypass?
Not sure on a lot of this, but asking for others opinions.

 

[labman]

Not really. At a given pressure, you will have greater flow with more area, and less pressure with more area with the same flow. The only way you would reduce the total flow would be if the larger filter had a higher bypass setting. The ADBV will also affect the initial flow.

How much filters bypass is a big black hole. Nobody here seems to say. I have seen reports here of a larger filter blowing off in the first block. This could easily happen if the larger filter lacked a bypass on an application that required one. Those reports would suggest that the filter should have been bypassing at first. I think everybody here acknowledges you can't just slap on any old bigger filter. You need to pay careful attention to bypass, gasket, and clearance. You also should verify the larger filter actually has more filter area.

 

[tom slick]

don't forget the conspircy theory that "oem automotive engineers are inventing different sized filters and designs to keep themselves in work".
we all know better then they do (by our vast and in-depth filtration design knowledge from years of reserch and education in the field)and know without a doubt that larger filters are better for all applications

 

[TallPaul]

Barring a filter the size of a 50 gallon oil drum, the filter size really won't affect oil pressure once the filter fills and the system pressurized. Oil pressure depends on backpressure from the bearings, oil galleries, etc. That will not change by using a larger or smaller filter.

 

[XS650]

quote:

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Originally posted by tom slick:
don't forget the conspircy theory that "oem automotive engineers are inventing different sized filters and designs to keep themselves in work".
we all know better then they do (by our vast and in-depth filtration design knowledge from years of reserch and education in the field)and know without a doubt that larger filters are better for all applications

---

Do you actually believe that the OEM automotive engineers get to use the filter that they think is the best filter for the application regardless of size or price?

 

[labman]

Good point XS650. Why does my 77 Chevy LUV 1.8 liter 4 get a huge PF 1177 and the 92 Grand AM with the 2.2 HO Quad Four get a smaller PF 47? Even the much less stressed Tech 4 in my daughter's 90 Beretta got a PF 52? ????????????

 

[XS650]

quote:

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Originally posted by labman:
Good point XS650. Why does my 77 Chevy LUV 1.8 liter 4 get a huge PF 1177 and the 92 Grand AM with the 2.2 HO Quad Four get a smaller PF 47? Even the much less stressed Tech 4 in my daughter's 90 Beretta got a PF 52? ????????????

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Go figure

The LUV was a Japanese truck (Izusu), could be the Izusu engineers had afreer hand at filter selection.

Fit while getting installed on the assembly line can also drive some design decisions, no idea if that's what was happening here.

Also, the people who make those decisions are human and different humans at that, so anything goes.

Remember back in the olden daze when spin ons first came out (1957?). Just about all Ford and Chrysler products used the same filter but GM started using a variety of filters right off.

Even several imports used the 3/4-16 thread that Ford and Chrysler used.

I don't admit this in polite company, but I once had a 1964 850cc Renault R8. (It would blow the doors off a stock same year VW Beetle though).

It's itty bitty filter came in a pretty French box . Inside was an itty bitty filter made in the US by Fram. The bottom looked familier so I tried a Fram for a Ford V8 and it fit perfectly. Looked funny though on the side of that little engine.
The Ford Application filter that held at least 4 times as much oil was also about 1/3 the price of the Renault boxed Fram.

 

[427Z06]

quote:

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Originally posted by tom slick:
don't forget the conspircy theory that "oem automotive engineers are inventing different sized filters and designs to keep themselves in work".

---

If you think engineers in a big corporation or organization have the last word in any decision made, you must be dreamin' kiddo.

 

[tom slick]

sarchasim doesn't type very well, i meant it all "tongue in cheek". i asked a very similar question about oversized and dual filter setups awhile back (year or so ago) and that was an idea that was brought up. i meant it as a bit of a joke.
i still haven't seen any real data that bigger is better (or worse). i am not against the idea, just interested in why there are so many different filter designs if really only a few wiykd get the job done.
mazda seems to be the only car company that uses a minimal amount of filters, for the last 10 years i think they only have 3 different filters.

 

[Razl]

quote:

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You need to pay careful attention to bypass, gasket, and clearance [with an oversized filter]

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Does everyone agree, regardless of your position whether to oversize or not, that a bypass psi rating in a larger filter (more media, less restriction) should be the same as the OEM size.

So mathematically, higher surface area = no change in bypass?

 

[labman]

quote:

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Originally posted by Razl:

quote:

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You need to pay careful attention to bypass, gasket, and clearance [with an oversized filter]

---

Does everyone agree, regardless of your position whether to oversize or not, that a bypass psi rating in a larger filter (more media, less restriction) should be the same as the OEM size.

So mathematically, higher surface area = no change in bypass?

---

--

I am not sure how important the exact bypass setting is, but no bypass where you need one is trouble.

Another point. I am not sure the Iffy lube where I dump my used oil carries as many filters as Wal-Mart. I am sure they are doing a lot of substituting, quite possibly under sizing. The Beretta came with a PF 47 sized QS in place of the PF 52. Wish I was into filter cutting back then.

[ August 23, 2004, 09:26 AM: Message edited by: labman ]

 

[427Z06]

quote:

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Originally posted by Razl:

quote:

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You need to pay careful attention to bypass, gasket, and clearance [with an oversized filter]

---

Does everyone agree, regardless of your position whether to oversize or not, that a bypass psi rating in a larger filter (more media, less restriction) should be the same as the OEM size.

So mathematically, higher surface area = no change in bypass?

---

Yes, ideally you want the bypass to be the same. However, even among the recommended sizes/models for an application by different filter manufacturers you'll find some differences. For example for a '02 Accord V6, Wix recommends a 51334/8-11psi and Purolator recommends a PL14459/12-15psi. So in reality a 3-4 lb difference isn't critical. A rule a thumb I use is, more media area, same or lower bypass, OK. But I would avoid going to smaller media area and a higher bypass pressure. And as Labman pointed, what is most critical, is if your application requires a bypass valve in the filter, definitely make sure you're using a filter with one.

In summary, a slightly oversized filter isn't some magical formula to get a million miles out of an engine. At best it provides a little extra insurance by allowing more filtered oil flow versus bypassed oil flow, and few other perks like increased oil capacity, for no additional cost. Especially if you go beyond the age old standard of 3K OCI. Proper maintenance and monitoring of all the other engine vitals is probably much more critical.

 

[T-Keith]

Bypass is media dependent. So there is no problem putting a 10psi bypass on a car asking for 2 or visa versa. The bypass is set to bypass the element when the media meets a certain restriction. This amount would depend on the filter's base restriction, restriction when clogged and amount of pressure differential the media can handle. Filter's with more restriction have a higher bypass setting and filters with lower restriction. Simple as that.

If anything applications without a bypass in the filter would be a more dependent on filter media because their bypass is set for the factory filter requirements.

-T

 

[TheFuror]

[[/qb][/QUOTE]As someone else said, why not? There are NO disadvantages to a larger filter. Nobody is throwing money at anything...a bigger filter cost the same as a small one. There are no good reasons to keep the stock filter, and there are plenty of good reasons to use an oversized filter... [/QB][/QUOTE]

Actually, there may be reasons not to use an oversized filter.

On my Avalanche, an oversized filter will put the end of the can right next to the exhaust header, whereas the smaller filter sits up from it.

Whether this proximity change of an inch or two is enough to make a difference is unknown to this old cowboy. However, it would not seem to be a good idea to have the filter sitting right next to the hot exhaust pipe.

Just my 2 ppm....

Bob W., a.k.a., "TheFuror"

 

[427Z06]

quote:

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Originally posted by T-Keith:
Bypass is media dependent. So there is no problem putting a 10psi bypass on a car asking for 2 or visa versa. The bypass is set to bypass the element when the media meets a certain restriction. This amount would depend on the filter's base restriction, restriction when clogged and amount of pressure differential the media can handle. Filter's with more restriction have a higher bypass setting and filters with lower restriction. Simple as that.

-T

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So, if I understand what you saying, you claim that the bypass pressure is ONLY based on how restrictive the media is given the media area is the same?

 

[rg144]

That would seem to be a sane idea (after reading the oil filter thread on BITOG for 100+ posts). If you're designing a filter you *really* want the oil to be filtered, not bypassed. So you bump up the bypass pressure if your media is restrictive. Besides, any oil pump should be able to punch a hole through even cardboard for media.

The only drawback would be how quickly pressure rises on the other side of the filter to start lubricating the engine. Surely not a concern of a filter designer.

 

[427Z06]

Sorry rg144 and T-Keith, but that dog don't hunt. You can find plenty of cases where through testing we find media that flows over 3 times as much in a particular application, has roughly the same area, and the bypass pressure is identical.

 

[rg144]

Bypass will *always* be identical because it the mechanical design.

Now the question is how much is going through those various medias and getting filtered? At best the modern filter design is there to catch the rogue metal shaving. And for that you could use the old VW screen mesh in the sump for a 'filter'.

A modern full-flow filter isn't filtering below 20-30 microns anyway (unless you have a bypass filter). That's why I prefer with the Motorcraft filters. During bypass oil flow simply jumps from inlet to outlet versus flowing the length of the filter. At least the net effect should be oil that stays cleaner a little longer.