Thread: Performance air filter

Originally Posted by ozrob

Here is some research that Bob has done on air filters...
I will stick to my paper element.
Air Filter Filtration Test - Bob is the Oil Guy - Bob is the Oil Guy

Better tests with the proper equipment on here

Originally Posted by rick130

Better tests with the proper equipment on here

http://www.aulro.com/afvb/good-oil/3...ve-answer.html

Hmmm.... Interesting.

It looks like he did a great job of doing the testing.
The particle size removal is dictated by the air hole size.
The airflow rate is dictaed by the number of air holes multiplied by their size. The diameter of the fibres comes into play here.

There is a practical limit as to how fine those fibres and holes can be, which is why the usual solution is to fit a filter with a larger area.

I had assumed that the K&N had reduced the fibre size which would give a greater hole to fibre ratio across the filter, and hence better flow rates. But it looks like that isn't the case.

Interesting.


Cheers,

Phill.

Originally Posted by Longtimer

....
The particle size removal is dictated by the air hole size.
...

No, sorry, that is completely incorrect. Air filters are not sieves.

e.g. Have a read here:

There is a popular misconception that fibrous filters behave like a sieve where particles above a
certain size are trapped and smaller particles pass through. While some filters such as membrane
filters in liquids do function this way, fibrous air filters defy common sense by actually trapping smaller
and larger particles more effectively than mid-sized particles.

[ame]http://www.tsi.com/uploadedFiles/_Site_Root/Products/Literature/Application_Notes/ITI-041-A4.pdf[/ame]

I see on Ebay in the UK there is a Pipercross higher performance air filter for the Discovery TD5. Anyone know if they make any difference? Any negatives? Thanks Iain

Originally Posted by HarleyPup

I see on Ebay in the UK there is a Pipercross higher performance air filter for the Discovery TD5. Anyone know if they make any difference? Any negatives? Thanks Iain

The best performance relies on your piston rings sealing. They won't do that if you compromise on air filtration.

Turbo diesel performance, from stock to significantly uprated, is not constrained by the air filter. At all.

No, sorry, that is completely incorrect. Air filters are not sieves.


e.g. Have a read here:

Isuzu rover , I don't think we are talking about the same thing here.
Your attachment refers to Fibrous filters , Ie the thick mats that are in airconditioners.
A K&N has a depth of only one layer of cloth and to quote from your attachment "it is the thickness, fiber diameter and density of the mat"

So a K&N has a very small thickness ie 1 layer.

Regards Philip A

How does the filter physically support itself? One layer of fibres won't have much mechanical strength.
If the filter only has one layer of fibres, it won't trap much dirt. Each layer will only trap a small percentage of the dirt, which is why efficiency increases with thickness and layers of fibres.
Aaron