Performance air filter

[TheStig]

Hi all just wondering if anyone has replaced the standard air filter with a performance one?? Any positives ?? Negatives ?? Or just your thoughts
Cheers

[BadCo.]

I am also curious about as I was thinking about it the other day. Is there a high flow aftermarket kit to replace the Donaldson?

[chopper]

I am also curious about as I was thinking about it the other day. Is there a high flow aftermarket kit to replace the Donaldson?

What vehicle/engine ?
Are you talking about the Big barrel on top at the back ( Donaldson type ) , I don't think you will get a filter with more surface area , ease of flow, than that , and one that still filters, a lot of "performance" filters perform but don't filter , just keeps the rocks out.

[BadCo.]

What vehicle/engine ?
Are you talking about the Big barrel on top at the back ( Donaldson type ) , I don't think you will get a filter with more surface area , ease of flow, than that , and one that still filters, a lot of "performance" filters perform but don't filter , just keeps the rocks out.

For the 4bd1, so yeah the big barrel at the back. Thanks for the info!

[TheStig]

I have a td5 and I have purchased a carbon fibre performance air filter.
Just was curious of other peoples thoughts .
I haven't fitted mine yet so can't give any feedback

[isuzurover]

...I have purchased a carbon fibre performance air filter.
...

Which manufacturer? Are you talking about the element or the housing?

There are several threads on here with actual filter test results for "performance" filters. http://www.aulro.com/afvb/technical-chatter/50650-air-filter-tests-finally.html

In almost all cases (with a 4x4 and especially a diesel) you are better off with OEM - or with a product from Donaldson, Fleetgard or MANN FILTER - unless you want to shorten the life of your engine...

[Phil B]

Agree with isuzurover.
I think that the point is cleaning the air effecively at the volumes the engine needs. I have read that the 4bd1 needs a flow of 275 cfm which is much higher than most "performance" filters can handle.
I am definitely no expert but my opinion is that effective cleaning is key.
Donaldson etc are designed to work at the required flow rates in construction or harsh environments. In my eyes that is the best protection you can get.
Phil

[TheStig]

This is the filter Land Rover Discovery Carbon Fibre Airbox Performance AIR Filter | eBay

Let us know your thoughts cheers

[Pedro_The_Swift]

http://www.aulro.com/afvb/good-oil/37343-air-filters-cleaning-k-n-test-definitive-answer.html;)

late edit:
sorry stiggy,, thought you were talking filter elements

is it a paper or foam element?

late edit 2;
it says removable washable,, but its a pre-filter?

[TheStig]

Land Rover Discovery Carbon Fibre Airbox Performance AIR Filter | eBay

[TheStig]

http://www.aulro.com/afvb/good-oil/37343-air-filters-cleaning-k-n-test-definitive-answer.html;)

late edit:
sorry stiggy,, thought you were talking filter elements

is it a paper or foam element?

late edit 2;
it says removable washable,, but its a pre-filter?


Umm not sure actually, I would have to take it apart to know for sure but I think it's paper

[isuzurover]

Can you take some pics (both whole and close up) of the element?

It looks like this:
OTA - OVAL TRUMPET AIRBOX | Products | BMC AIR FILTERS (http://www.bmcairfilters.com/air-intake-systems/ota-oval-trumpet-airbox/parts_prd_pr3_14_1.aspx)

The air flow/pressure stuff in that blurb is rubbish.

As for the filter element, it does not bode well:

The air filter ... multi layer pre-oiled filtering material ... it is possible to regenerate the filter by washing and re-oil operation ....

I have seen other similar items which say they have a cotton filter...

[TheStig]

I think I attached them..

[TheStig]

...

[isuzurover]

I think I attached them..

All I can see is an ebay link to the filter housing???

[TheStig]

Here ?? Sry I'm new to this

[isuzurover]

Here ?? Sry I'm new to this

That is just the usual cotton crap that all the "performance" filter companies sell. Don't use it if you want your engine to last...

[Longtimer]

What's so destructive about the oiled cotton filters?


Cheers,

Phill.

[Dougal]

What's so destructive about the oiled cotton filters?


Cheers,

Phill.
They don't filter.

[ozrob]

What's so destructive about the oiled cotton filters?


Cheers,

Phill.

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 (http://www.bobistheoilguy.com/air-filter-filtration-test/)

[isuzurover]

What's so destructive about the oiled cotton filters?


Cheers,

Phill.

The fibres are too coarse to filter properly. Air filters are not sieves, filter capture efficiency is inversely proportional to fibre diameter.

[rick130]

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 (http://www.bobistheoilguy.com/air-filter-filtration-test/)

Better tests with the proper equipment on here ;)

[Pedro_The_Swift]

Better tests with the proper equipment on here ;)

;)
http://www.aulro.com/afvb/good-oil/37343-air-filters-cleaning-k-n-test-definitive-answer.html

[Longtimer]

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.

[isuzurover]

....
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.

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

[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

[Dougal]

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.

[PhilipA]

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

[Aaron IIA]

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

[rick130]

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
Err, Philip, isn't a woven strand of cotton a multitude of fibres possibly thicker than a comparable cellulose fibre (paper) filter ?

[rick130]

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
As Dougal, said the most important filter for you engine is the air filter.

PiperCross are oiled foam high flow filters so it's debatable whether they filter as well as an OEM paper filter.

[BadCo.]

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.

So having the same style filter with a larger area and a larger diameter feed to the engine wouldn't increase performance?

Not being smart, just thinking out loud..

[JDNSW]

Depends on whether performance is restricted by the existing filter. In a properly designed diesel, simply changing the filter to one with less restriction should make no difference - if it does, then the engine is overfuelling with the existing filter. (There will be a very slight reduction in the pumping losses of the engine, but I doubt it would be measurable, let alone perceptible)

In my humble opinion, the major attribute of so-called performance filters is that they abrogate the aircleaner's other function, that of intake silencer, so that the car sounds faster!

John

[isuzurover]

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

No not at all. They are all part of the spectrum of fibrous filters.

HVAC filters you refer to are generally very loosely packed, thick media, with very low capture efficiency. They generally have an electrostatic charge imparted on the (plastic) fibrous media in order to improve capture efficiency.

Car air filters are also fibrous filters, whether made of cellulose, polymer or cotton fibres. Although they look "thin" to your eyes, under a microscope (and to the microscopic particles), they are a comparatively thick media. e.g. I have microfibre glass media here that is 0.4 mm thick, but with a mean fibre diameter of 100 nm, that is a lot of fibres the air must pass by in order to pass through the filter.

The only air filters which are not fibrous filters, are foam and membrane filters - the latter not being used for engines due to very high pressure drop.



So having the same style filter with a larger area and a larger diameter feed to the engine wouldn't increase performance?

Not being smart, just thinking out loud..

Of course on a diesel any pressure drop both before the inlet valves and after the turbo will create pumping losses as it is extra energy which needs to be overcome. However the air filter is very low down on the list, after the exhaust system, intake system, intercooler, etc... If you had just a dump pipe after the turbo (no exhaust) and a very short, properly sized intake with minimal bends, then it might be time to look at the filter.

Before you get that far, there are some other things to consider.

Since filters aren't sieves, changing the surface area of the media (keeping everything else the same) will change the performance of the filter - i.e. how much dust of each particular size it captures. Increasing filter area will decrease flow velocity and decrease inertial capture forces.

[two up]

What hasnt been mentioned is airspeed over the filter media. Too high and your only filtering rocks.

[PhilipA]

Of course the K&N is part of a spectrum. But I must disagree about a cotton thread I believe that individual ctton fibres would be bound too tightly to allow any air flow between only around the complete thread.
I believe your example shows a relatively deep complex of fibres.

In any case there are many tests over the years that show that in practice K&N filters are inefficient.
As well as that the K&N oil is well known to foul MAFs which is the last thing a TD5 owner wants and that was the OP. Of course K&N dispute this but in reality it is a big problem if owners are unable to achieve the oil levels demanded of K&N to not foul MAFs.
Theory is one thing Practice another.






Err, Philip, isn't a woven strand of cotton a multitude of fibres possibly
thicker than a comparable cellulose fibre (paper) filter
Regards Philip A

[Dougal]

So having the same style filter with a larger area and a larger diameter feed to the engine wouldn't increase performance?

Not being smart, just thinking out loud..

Absolutely. A good and really big filter will both filter really well and give almost no noticable pressure loss.

But even a correct sized filter (the one with your 4BD1 is rather large) will flow more than you ever need while providing an acceptable pressure drop even with a whole shovel full of dust trapped in it.

[isuzurover]

Of course the K&N is part of a spectrum. But I must disagree about a cotton thread I believe that individual ctton fibres would be bound too tightly to allow any air flow between only around the complete thread.
I believe your example shows a relatively deep complex of fibres.

...



I think we can probably agree the K&N media is a very poor design. Woven cotton makes a very poor filter, however it still works as a fibrous filter more than any other mechanism.

There are "holes" in the weave of a KN that you can see (see image), however the air wouldn't flow only through these holes - and even if it did, under a microscope there would be some fibres in the "hole/pore" area...

https://www.aulro.com/afvb/images/imported/2014/08/1036.jpg

[BadCo.]

Absolutely. A good and really big filter will both filter really well and give almost no noticable pressure loss.

But even a correct sized filter (the one with your 4BD1 is rather large) will flow more than you ever need while providing an acceptable pressure drop even with a whole shovel full of dust trapped in it.

Good to know, thanks!

[TheStig]

Air filter fitted

[Dougal]

Is that a filter?

[BadCo.]

So, did you ditch the Donaldson for that?

[rick130]

I would love to see the before/after Si and wear metals in a series of oil analysis with that.
Don't think it'd paint a pretty picture.....

[sheerluck]

Is that a filter?

Of course it is! Freshly stolen off a passing Suzuki Swift.

[bee utey]

Is that a filter?
It's a species of Pod filter. If you drive the vehicle through a horticultural crop it will husk the pods and allow the engine to ingest the peas, which are obviously nutritious.

[rick130]

It's a species of Pod filter. If you drive the vehicle through a horticultural crop it will husk the pods and allow the engine to ingest the peas, which are obviously nutritious.
Bwahahaha ! :D

[Ancient Mariner]

I could'nt see a filter only something that looked like a hump hose:confused:

AM

[isuzurover]

It's a species of Pod filter. If you drive the vehicle through a horticultural crop it will husk the pods and allow the engine to ingest the peas, which are obviously nutritious.

:D:D:D:D:D:D:D:D

I clicked on this thread yesterday and thought OMFG someone still went and fitted one of those despite this thread...

[Beery]

:D:D:D:D:D:D:D:D

I clicked on this thread yesterday and thought OMFG someone still went and fitted one of those despite this thread...

Apart from installing a "performance" filter, the other thing that people should never ever ever do is take the filter out for a look, give it a whack on the wheel to knock some of the dust out, and then stick it back in! You'll do more damage than good and end up with dust on the 'clean side' and risk tearing the filter media.

Makes me cringe when I see someone do this.

If you're worried about filter restriction, install a restriction indicator!

[460cixy]

Air filter fitted


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