K&N air filters, whats your opinion?

[Ford17]

My understanding is in most cases the factory air box and filter are surprisingly efficient, and don't really benefit much from being changed or replaced.

Also recall seeing a test done where a very dirty standard paper air filter didn't hamper performance very much, if at all.

[superyob]

Aside from the filtering capacity or lack thereof, the K&Ns I had on my Suzuki Katana in the 80s did not create the venturi effect for maximum air velocity of the original air box. I have never had one on a car though so I am assuming they replace the standard filter inside the air box?

[99AUXR]

Originally Posted by superyob

Aside from the filtering capacity or lack thereof, the K&Ns I had on my Suzuki Katana in the 80s did not create the venturi effect for maximum air velocity of the original air box. I have never had one on a car though so I am assuming they replace the standard filter inside the air box?

Unless you have a custom intake on the turbo side in which case RIP using paper filter.

[jpblue1000]

Originally Posted by sprintman1

Air flow yes, cleaning no.

Actually both
http://www.bobistheoilguy.com/airfilter/airtest3.htm
might not be the same amsoil you used!

Just saying

JP

[sprintman1]

Originally Posted by GT450

As some have said , it's really horses for courses. I use both and find the oiled filter more economical over time and unless you're into some really dirty environment then there's not going to be any difference over the life of an engine.I have yet to read where an oiled air filter caused damage when used correctly.Maybe there is a chart for that too at the UOA section on BITOG.
Same as i use fully synthetic oils in all my cars ,it may not in the end be any different but it gives me peace of mind and there is definitely no weeping seals or oil leaks that i have experienced with mineral oil.
All i can say is the air must be very dirty in the ACT if K&N won't do a good job of filtration.

They don't do a good job of filtration anywhere!

[sprintman1]

Originally Posted by jpblue1000

Actually both
http://www.bobistheoilguy.com/airfilter/airtest3.htm
might not be the same amsoil you used!

Just saying

JP

Amsoil here is pre Absolute Efficiency

[mik]

In the old days i could always see a fairly decent improvement changing the standard air filter and air cleaner, these days i dont think id bother swapping out the flat panel filter for something else , not unless i was going the whole hog on modifications after every last tiny ounce of HP,
air filter on its own ? i`ll eat couple less burgers before i go for a run ; ).

[XG_Falcon]

Originally Posted by mik

In the old days i could always see a fairly decent improvement changing the standard air filter and air cleaner, these days i dont think id bother swapping out the flat panel filter for something else , not unless i was going the whole hog on modifications after every last tiny ounce of HP,
air filter on its own ? i`ll eat couple less burgers before i go for a run ; ).

I think the main reason for this is that cars are engineered to get maximum fuel efficiency now. As a result, modern OEM air intakes are usually more cleverly designed than those in older cars. I'd say manufacturers do the bulk of their testing with the standard filters but I'm only really guessing.

[99AUXR]

Originally Posted by mik

In the old days i could always see a fairly decent improvement changing the standard air filter and air cleaner, these days i dont think id bother swapping out the flat panel filter for something else , not unless i was going the whole hog on modifications after every last tiny ounce of HP,
air filter on its own ? i`ll eat couple less burgers before i go for a run ; ).

I certainly would bother putting a K&N in a standard airbox/car as a modification.

[Express]

Stepping away from the particle capturing properties of the filters and looking instead at their performance qualities, I tend to believe it’s the redesign and/or relocation of the air box over the factory item in some makes of car that can give an increase in HP and not swapping out the filter.

If all things are equal and the filters are all of reasonable quality, the actual difference between them is minimal.

I’ve tried a few different types of aftermarket filter boxes as well as experienced a few factory setups and the different schools of thinking is quite amazing.

For example on a LS powered Holden an aftermarket over the radiator type of air intake versus the original factory box located to the side with a more restrictive opening will see the over the radiator design achieve better gains when the engine is being tuned.

This is three types that I’ve had on my LS based cars.

The first is a modification of the factory unit where I retained the paper filter.

The box is in its original location but more air gets in because of the unseen additional hole made into the bottom of the box and a bigger diameter pipe added between the box and throttle body.


HSV VE



The second is where the factory setup has been completely dumped and an over the radiator unit with a K&N filter has replaced it.

It’s a plastic box that would gather air from just under the bonnet lip and under acceleration the box would deform and suck in on itself and eventually cause a minor restriction to the air passage.


SSV Ute



The third is basically the same as the second with a couple of differences.

First it is made of metal and doesn’t deform under acceleration and secondly it has a much bigger filter and the radiator has been titled back to allow it to travel down the front of it.

When tuned the gains achieved over the base stock readings were much bigger on the over the radiator types than the modified box and pipe setup.


SS Ute



To add to the mix is a standard air box on a VS HSV Commodore.

It collects air from the front then sends it to the side and then back again.

It seems to be an inefficient design to me which shows I don't have a clue.

The only change was replacing the paper with a K&N.

I had already had the car tuned prior to this and there was no noticeable seat of the pants improvement with the K&N but there was definitely a big increase in induction noise.


HSV VS



Now for some factory setups.


The C63 has two throttle bodies at the back of the engine which are fed via two over the radiator inlets at the front.

First off AMG when designing this engine said more horsepower was achieved by having the throttle bodies at the rear instead of at the front.

If you’re interested their reasoning it is available by searching the net and as they built this engine from scratch and could have placed the throttle bodies where ever they liked there must be something in this decision.

Secondly in Australia and Europe there are two paper filters, one on each side.

The US spec cars have four.

In addition to the two paper filters they also have a charcoal filter on each side and when chasing horsepower these two are the first things thrown into the bin.

I’ve never seen any info where replacing the filters with aftermarket ones has made any real improvements but swapping the factory filters for BMC’s is popular.

The mod done to this setup is to replace the ducting and mouths with aftermarket units that have a much larger diameter and opening.


C63



The BMW for its twin turbo inline six also collects from two locations behind the kidney grills in front of the radiator and sends it to an air box at the side.

As with the AMG, replacing the factory setup with a bigger bore filter system seems to be the secret to obtaining more power.


135i



The last is a very recognisable 1970’s muscle car setup with the air being captured straight off the bonnet and down through a paper filter.

Holden went the other way for their Toranas and collected via a reverse cowl.

With so many different ideas and there are more than the ones I have, it makes you wonder how much difference replacing the filter alone makes.

Given they all come from the factory with paper filters, probably little.


XY

[BLDNUT01]

this might help, a couple of aussie blokes doing a review on pod filters and about 7 min they chuck in a what appears to be a K&N filter in
https://www.youtube.com/watch?v=PAIxeQUSg-Q

[MattSAU2XR8]

I always like to refer people to this...

http://www.autospeed.com/cms/article.html?&A=111486

Bottom line seems to be that a different filter element will only help if there is a considerable pressure drop across the filter.

This has also been covered a fair bit here...

http://http.www.fordforums.com.au/vb...php?t=11437570

[bangm001]

All of my cars run a K&N. Being able to clean it and re-use is enough reason for me. I even sold mine for what I paid for it after i sold my FG so it was a FREE filter for 5 years!! There is slightly more induction noise with this filter on my turbo cars also, does this mean it flows better, I dont care really..

[XB GS 351 Coupe]

Been using K&N filters in all my cars for decades, never been an issue, could never contribute any engine damage or wear to using it.

They definitely breathe better, and if using a whole filter assembly will definitely increase power on a old school V8 set up, not sure on newer air boxes, but I still use them in my new cars as well.

I have seen just swapping paper element for k&n make about 5-7rwhp on an XY GT, have seen this over and over on a dyno, and repeatedly seen the reverse effect of going back to paper.

Swapping out the whole filter element gives even better results.

[GO FURTHER]

While I believe that K & N filters flow better (at the cost of less efficient filtration) than paper filters, it's not the filter itself that makes the major difference to intake air restriction .... It's often the airbox itself, especially if the car is tuned or turbo model

Just changing your standard paper filter to a K & N panel filter isn't going to make a noticeable difference to performance.

However, change your air box to something like a Streetfighter Airbox, or the Herrod air box with K & N pod filter, or even better a turbo side airbox on a turbo falcon and there will be a noticeable difference in throttle response, fuel economy, and a small Kw gain.

For example Streetfighter claim on their website;

FG 4.0 N/A 7-10 rwkw gain
FG 4.0 XR6 and F6 Turbo 8-12 rwkw gain
FG 5.4 Boss XR8 / GT 8-12 rwkw gain

Herrod motorsport, a respected name in Ford performance, make the following claim;
"In conjunction with our Cold Air Induction systems.... In house testing on our Mainline AWD chassis dyno shows that replacing your current air filter with a K&N Hi flow unit, results in Increased Power and better Fuel Economy"

And in regards to a turbo air side box with K & N type pod filter.... I will quote what Ratter (Pit lane Performance) wrote back in 2011...

"Well today I had a little time to test things, so the G6ET was ran up on the dyno and a couple of base lines runs done to get a fair level for comparison, it ran 316, 316 and then 312 rwkw back to back runs, the battery was then removed plus the factory intake pipe from the turbo. We fitted the intake box, filter, boost pipe and intake pipe and connected the battery terminals to a set of jumper leads with the battery out of the car, rather than wasting time fitting and wiring it all up as I wanted to get similar conditions to test in.
Car was left strapped to the dyno etc to eliminate any changes.
The first run with the turbo side air box was 332 rwkws, but figured the ecu had not corrected data based on the changes, so did a couple more runs which saw 324, 324 and 328 rwkw. The air box was then removed and the car refitted with the parts as the original tests and run up again and saw 315, 315 and 312 rwkws."

[ebxr8240]

The oil in them can lead to maf issues ..covering hot wire .

[GO FURTHER]

Originally Posted by ebxr8240

The oil in them can lead to maf issues ..covering hot wire .

But.... For the last 13 years since the BA.... Falcons don't have MAF sensors. So not an issue with newer Fords.

[xxx000]

Originally Posted by Raptor

So why do dirt bikes all use oiled foam filters?

I'm with poster 2 and 10 on this. All fit for purpose with pro's and con's and the lower filtration rate isn't going to make a bit of difference for all practical purposes.


.

So that the owners aren't having to continually buy replacement paper filters. Instead they can service their oiled filter themselves.

[Road Games]

More noise = WIN

Looks purposefull = WIN

Lasts forever = WIN

I havn't reoiled mine in over 12months i wash it with degreaser and refit it...

Runs hard and sounds tuff doing it , cannot get that same satisfaction from a factory filter and std airbox !

[Burnout]

Been running a k&n on mine since the airbox had to be removed to make room... I clean and re-oil it every service, (10,oookm). Had no issues.
When the Ute was NA it had a flat panel k&n fitted in the FoA airbox with the F6 intake & a Territory air pipe. No issues.
Vehicle has 273,oookm on it now.

[sprintman1]

Originally Posted by Burnout

Been running a k&n on mine since the airbox had to be removed to make room... I clean and re-oil it every service, (10,oookm). Had no issues.
When the Ute was NA it had a flat panel k&n fitted in the FoA airbox with the F6 intake & a Territory air pipe. No issues.
Vehicle has 273,oookm on it now.

Get a UOA and post the results

[TheSneakiness]

Seems to me someone has an agenda and those type of people really annoy me, hell K&N wouldn't offer a million mile guarantee if it didn't work.

I had a K&N pod filter on my AU as part of the old Jim Mock Motorsport cold air system utilising a modified EF airbox (my AU when I bought it had an exposed no-name pod filter attached which was quickly removed) and I've had K&N panel filters in a BA Falcon and a NS Pajero with no issues at all. Kept it serviced when the car was serviced, sure it got dirty but no dirtier than a normal paper filter.

[GT450]

Originally Posted by sprintman1

They don't do a good job of filtration anywhere!

In your humble opinion, and I am guessing you are basing your facts from what you have read not from actually using one. if you have used one what problems did it cause?
GT450

[sprintman1]

Originally Posted by GT450

In your humble opinion, and I am guessing you are basing your facts from what you have read not from actually using one. if you have used one what problems did it cause?
GT450

Unlike you I read around 5 UOA's a day and have done for over 15 years so I have a pretty fair idea of what works and what doesn't. And yes there was one on the BMW when purchased but it was quickly consigned to the bin where it belonged.

[PHANTMXR6]

The life of my engine has been sampled in the link below.

I've always used a K&N on this engine since it was rebuilt, and used a panel filter prior to fitting the Herrod airbox and K&N pod.

My Si sample results are nothing for me to be concerned about and due to the simplicity of use, cost and some slight bonus in horsepower, I will continue to use my K&N filter.

http://fordforums.com.au/showthread....ght=oil+sample

[GO FURTHER]

The problem with K. & N. Filters letting more dirt in that some people experience, it not the filter itself but poor re-oiling of the filter in subsequent cleaning and maintenance schedules over its lifetime.

The only way to do it properly after a thorough clean, is to use the manufacturer's specified oil, and purchase the geniune K. & N. Oil.
Problem is many people don't want to spend the $20 or so for the oil, and use cheap substitutes.
Heck, I've seen qualified mechanics simply spraying the filter with a few short squirts of WD40!!... simply not good enough!

The next issue is proper technique in applying the K. & N. Oil.....
The oil should be run methodically down the top of each pleat, and along the inside between each pleat of the filter.
The end result should look like a nice even bright pink, just like when the filter was bought new!.... If not, and you have white or gray patches on the filter medium in places, then you have not oiled it properly. It should not be dripping wet either.

Man..... A cotton filter properly covered with the right oil is so sticky to airbourne dirt, its filtering properties are excellent.

[sprintman1]

Better reusable filters are available that don't require oil. Better filtering/airflow, look way better (CAI style) and cheaper, a win in every dept.

[GT450]

Originally Posted by sprintman1

Unlike you I read around 5 UOA's a day and have done for over 15 years so I have a pretty fair idea of what works and what doesn't. And yes there was one on the BMW when purchased but it was quickly consigned to the bin where it belonged.

You have too much time on your hands and whilst I have absolutely no objection to anyone voicing their opinion on these forums , heresay without actually using said product is merely mischief .
You are in your own way calling all of those that use and like K&N filters idiots or at best liars. As I said all types of filters have specific types of usage so can we not let the users be happy in their choices without the dogmatic denigration becuse you read 5 UOAs aday.
GT450

[Giant]

I like the K&N then again i do like pink bits

[PHANTMXR6]

Originally Posted by sprintman1

Better reusable filters are available that don't require oil. Better filtering/airflow, look way better (CAI style) and cheaper, a win in every dept.

Would you care to share these with the group please?