L20252 - 25-35psi bypass DP

[Shannow]

Looking for filters for my new toy (1980 BMW), and found that they specify a filter that bypasses at 25-35psi. Though that extreme...then found oil pressure at max speed is 75 to 87psi.

3/4-16UNF thread. 70mm gasket diameter.

 

[Gary Allan]

VW/AUDI filters are of this like bypass rating. 3/4-16 thread too. They have, at least those that I've seen the internals of, wire reinforced media (assumed) to withstand the high differential.

I have yet to reason why they spec such a high bypass threshold. An engine is an engine and flow is flow. The pressures are nothing out of whack with other engines (perhaps on the high side). I would say that for me to make sense out of the practice, the pump relief limit would have to be extreme (like 100 psi in your case due to your indicated readings of 75-87 - assumed warm) ..otherwise, when cold, you can surely be reducing oil flow substantially.

This is a German thing ..yet I don't get it.

70mm, if I did the math right, falls into the 2.8 range of gaskets.

Here's a VW/Audi filter in WIX

Part Number: 51393
UPC Number: 765809513938
Principal Application: Audi (71-06), Volkswagen (96-05), Lotus (71-74)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.820
Outer Diameter Top: 3.020
Outer Diameter Bottom: Closed
Thread Size: 3/4-16
By-Pass Valve Setting-PSI: 33
Anti-Drain Back Valve: Yes
Burst Pressure-PSI: 410
Max Flow Rate: 7-9 GPM
Nominal Micron Rating: 28

Gasket Diameters
Number O.D. I.D. Thk.
Attached 2.800 2.450 0.230

 

[Shannow]

Gary,
when I saw the thread and gasket, I immediately checked the engine for enough room to fit a Ford filter (Z9 in local parlance). Cheap as chips, even in a decent brand.

Plans were shattered when I saw the bypass setting.

 

[unDummy]

z9= 'FL1a' or PH8a size. Thats an oversized option and should work well if there is enough 'mount' for the gasket.

The required filter is similar to the FL2005, FL400s, or Ph3600.

I wouldn't worry about bypass setting.

 

[Gary Allan]

I too tend to discount the importance of the bypass setting. It's because of the high bypass setting that they make it such an expensive filter by reinforcing the media with wire mesh and whatnot. I can't see a reason not to use a regular 3/4-16 filter in its place. There are plenty of PH8A and kin that see like pressures and like flows.

I'd actually welcome someone to "set me straight" on my error in view ..it it actually is in error. The only thing that I can see as a benefit is either continued filtration where bypass would normally occur (transitions when the pump is in relief) or extended loading with continued filtration. Other than that, I just don't get it.

 

[Shannow]

Dunno myself on the high bypass, unless it's to make sure that bypassed oil doesn't happen unless things are dire.

Gonna fill the thing with Delvac MX tomorrow, drive a few weeks, and Auto-Rx it.

Will leave the standard filter on for clean and rinse, then switch to something more standard.

BTW, the proper fitment is $18 (Ryco), versus $8 for a Z9. (Pure 1 Z9 is around $20)