The Mann OEM Audi filter question

[ZeeOSix]

The by-pass opening pressure of the filter is 43.511 PSI :
https://www.mann-filter.com/us-en/c...t.html/w930/21_mann-filter.html#technicalData

43.511 PSI is very high, wonder why. Too high a bypass setting could cause the oil pump to hit pressure relief earlier if the dP gets that high, and cutting back pump flow before the filter bypass valve opens.

They do show the 4.3511 PSI above in the bullet info. Slipped a decimal point.

 

[rollins.]

Here some more on the specs (they've probably changed something in the last two decades) :
https://www.audiworld.com/forums/12...-who-choose-use-mann-w940-25-instead-2592144/

 

[ZeeOSix]

Here some more on the specs (they've probably changed something in the last two decades) :
https://www.audiworld.com/forums/12...-who-choose-use-mann-w940-25-instead-2592144/

From link above ... not real efficient.

W940/25: efficiency (ISO 4548-12) 50% at 18 micron
W930/21: efficiency (ISO 4548-12) 50% at 14 micron

 

[rollins.]

Yep . Bumped into an older discussion :

C

Thread 'Finally found official Mann filter efficiency #'s'

Jan 30, 2018

https://oe-products.mann-hummel.com/fileadmin/user_upload/kataloge/MANN_HUMMEL_Liquid_Filters_EN.pdf

There are a lot of filter efficiencies listed here. Unfortunately, they don't include the microglass elements.

It was previously stated on this forum (many times) that the Mann W 719/30 spin on filter was 99.5% to 99.9% efficient at just 9 microns. This information apparently supplied directly by a Mann engineer.

Turns out that it, and many other Mann cellulose filters and elements, are 99% at 38 microns and 50% at 20 microns.

• CharlieBauer
• Replies: 25
• Forum: Engine Oil Filters

 

[ZeeOSix]

Yep . Bumped into an older discussion :

C

Thread 'Finally found official Mann filter efficiency #'s'

Jan 30, 2018

https://oe-products.mann-hummel.com/fileadmin/user_upload/kataloge/MANN_HUMMEL_Liquid_Filters_EN.pdf

There are a lot of filter efficiencies listed here. Unfortunately, they don't include the microglass elements.

It was previously stated on this forum (many times) that the Mann W 719/30 spin on filter was 99.5% to 99.9% efficient at just 9 microns. This information apparently supplied directly by a Mann engineer.

Turns out that it, and many other Mann cellulose filters and elements, are 99% at 38 microns and 50% at 20 microns.

• CharlieBauer
• Replies: 25
• Forum: Engine Oil Filters

The most efficient filters shown in that table are 99% @ 38u, and most show to be 99% @ 50u.

 

[Georgi1]

I am surprised to see the low efficiency at least what it was. I am sure many years ago the filtering media was way different. I will cut open this filter one of those days and show you what's inside. Maybe I will find very old filter sitting around too.

43.511 PSI is very high, wonder why. Too high a bypass setting could cause the oil pump to hit pressure relief earlier if the dP gets that high, and cutting back pump flow before the filter bypass valve opens.

They do show the 4.3511 PSI above in the bullet info. Slipped a decimal point.

Wow. I did not see the bottom chart where it has different decimal. I only copied the top part. Still high at 3bar(~43.5psi)

I measured the holes on the Mann. It measures around 7.9mmx6.8mm since it is not an actual circle.
Purolator measures 7.1mm hole

 

[ZeeOSix]

I measured the holes on the Mann. It measures around 7.9mmx6.8mm since it is not an actual circle.
Purolator measures 7.1mm hole

What's the total combined flow area of the sum of the holes on each filter. Looks close, which means the hole design doesn't really matter with respect to the dP vs flow performance.

 

[Georgi1]

It is not close,but close to double
Let say we take the bigger side for the Mann 4x7.9=31.6
Purolator is 8x7.1=56.8

I am still not going to use the Purolator thou

 

[ZeeOSix]

measured the holes on the Mann. It measures around 7.9mmx6.8mm since it is not an actual circle.
Purolator measures 7.1mm hole

See what you're saying now.

Mann
(7.9 mm x 6.8 mm) x 4 holes = 214.9 mm^2

Purolator
7.1 mm dia hole = 39.6 mm^2
8 holes x 39.6 mm^2 = 316.8 mm^2

Mann/Purolator ratio
316.8/214.9 = 1.47 (47% larger)

A hole with 215 mm^2 has a diameter of 16.6 mm, which is probably about the size or a bit larger than the oil feed hole in the threaded filter mount. Still not going to make any real dP vs flow difference (like 1 PSI or less of dP at 10 GPM with hot oil, ref post 14) that matters to a positive displacement oil pump.