Warner PH2850 Substitute for FL1A?

[miraCRD]

I am looking for guidance if is would be safe to use a Warner PH2850 on an application that calls for the common PH8A/FL1A? I have several of the Warners that I'd like to use up. From what I am able to figure out, the 2850 and PH8A are identical except the 2850 has a higher bypass rating (30 psi verses about 10 psi on the PH8A).

I also understand that the bypass valve will only come into play once the filter is clogged/saturated with dirt, so if I use these for 3K OCI's I'd be fine?

 

[Chris142]

My scout originally called for the 2850 filter. Fram(when I used frams) quit making it and recomended I use the PH8A.

If I remember correctly the bypass pressures between the 2 frams was only a couple of PSI.

 

[Gary Allan]

This is for some Euro engine that has a high pressure limit on the oil pump.

The bypass valve ALSO opens when the filter becomes saturated. The bypass valve is to limit the filter's resistance when the oil pump is in relief. The bypass valve setting limits the stress that the media sees when this occurs. That filter HAS to have a reinforced media (wire mesh probably).

The potential is this:

Let's say you've got a 60lb limit on your oil pump. You start up and your pump goes into relief. 30lbs of pressure can be dissipated across the media and 50% of the flow to the engine shunted to the suction side of the pump. It can take longer to fully envelope the engine with oil and produce back pressure.

I would go the other way around before I used the 30lb bypass valve on a 8-15 spec'd engine.

..but ..that said, if you've got a real gauge ..and know your peak cold temp pressure, you should be able to see if you're hanging too long at the relief level.

The filter, itself, normally presents very little resistance ..even when partially saturated, as long as you are below the oil pump's relief level. The back pressure developed by the engine trumps it big time. It's just a variable percentage of that depending on available open media and oil viscosity.

 

[miraCRD]

Thanks for the responses & the thorough info. I did not realize that the relief valve can have an impact just by getting saturated with oil. I thought only dirt could "clog" it to the point where the relief valve would close.

FYI my desired application is on a 1991 Toyota Land Cruiser with the 4.0L 3FE engine. I do not know what the oil pump limit is but I imagine it would be listed in the factory service manual?

It's interesting, on the box for the 2850 it lists the applications as being all Datsun/Nissan vehicles....260Z, 280Z, 810, 610, 200SX, etc. I wonder why those vehicles would have had a need for the higher pressure relief valve?

Also, is there any way to actually test a filter's bypass pressure rating before installing it on an engine? I ask this because I was getting that 30psi number from crossing the Warner to a Wix...I cannot find the actual published spec for the Warner.

 

[Gary Allan]

The number should meet or exceed OEM spec's.

The only way to test it is to remote mount it and put upstream and downstream gauges on it (or a differential pressure gauge).

I was always curious why BMW/VW/AUDI spec'd these high bypass valve settings on their filters. It was way weird compared to our more mundane engines. The flow dynamics aren't any different ..but it surely bugged the heck out of me. Finally,
Doug Hillary shed some light on it. Those engines tend to have very high pressure and, in the case of the Euro's, spec relatively heavy oil. Their peak pressures may be 100-135+ and may be slammed up against the pump relief for 20 minutes or more at operating speeds (mundane operating speeds). With those upper strata conditions, the engine could be in bypass for its entire life if a lowly 8-11 PSID bypass valve was used. Hence, they get a 30 psid so that oil is filtered more or less, full time ..or a high percentage of the time. It's factored into the design to have whatever share that 30lbs of apparent restriction produces in reduced flow.

There are other ways to view this and other things that come into play when you're into higher volumes and higher pressures. Most filters have a static PSID rating at a given flow at a given viscosity. Let's say it's 10 PSID @ 10GPM with an Xx weight fluid. That's all fine and good ..except the vast majority of engines will never process more than 5 gpm of oil over the full range of the rpm band. These are levels that some engines can attain ..and therefore you sorta have to qualify the view when discussing them.