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#1 2005-06-21 13:24:06

KoRn
Member
Registered: 2005-06-03
User Number: 147
Posts: 23

K&N Air Filter

Did anybody changed their air filter for a K&N on their AERO ?

Does it makes a difference ?

I wonder if the right K&N part number is 33-2075 since they dont show that it fits on the 9-2x but they do say it fits on the WRX

Thanks for your help

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#2 2005-06-21 13:56:10

PCPCDALLAS
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Registered: 2005-05-14
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Posts: 759

Re: K&N Air Filter

I don't know the model # but the K&N filter that fits the WRX definitely fits the 92x.

Example: http://pcpcdallas.com/index.asp?PageAct … rodID=1247


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#3 2005-06-21 14:38:54

Anand
The Dude Abides
Registered: 2005-05-29
User Number: 113
Posts: 2036

Re: K&N Air Filter

I had a K&N in my Prelude and I can't say it made a noticable difference.  It did seem to make it a little louder on WOT but my butt dyno didn't feel a thing.  I don't plan on getting one of my Saabaru.  There are plenty of downsides:

1.  Price.  Unless you live in a really dusty area and have to change air filters far more often than usual, it will take several years before you break even.

2.  Dust.  The filters let in more air but let in more dust as well which will end up in your oil, so your oil won't last as long.  Since most people change their oil before it's really necessary anyway this isn't a huge deal but something to think about.  Also note that the restriction of K&N type filters increases exponentially with the amount of dirt they've captured, unlike regular filters which ave a much straighter curve.  What this means is that clean vs. clean, the K&N will be much less restrictive than a paper filter but after a few thousand miles, they can actually become more restrictive.  There are some good graphs here:

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

3.  Time.  Cleaning, drying, and reoiling the filter can take several hours because the filters should be allowed to dry on their own.  This is alot more downtime than the 5 minutes it takes to replace a paper filter.


2005 Arctic Silver 9-2x Aero 5-Speed w/ Sport Package

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#4 2005-06-21 16:24:38

Andrew
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From: Scarborough,ME
Registered: 2005-05-23
User Number: 80
Posts: 4413

Re: K&N Air Filter

I have heard the oil in the filter is not good for the turbo.  Anyone have facts on this.  I had a K&N in my previous car and I liked it, sound and a little bit of added performance, but not a lot.


2005 silver car

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#5 2005-06-21 16:34:37

salaki
I love Pink...
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Registered: 2005-06-16
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Re: K&N Air Filter

The oil is not good for the MAF sensor.

You can use KNN but you need to make sure it's not too much oiled.

People buy KNN (At least WRX guys) because of its million miles warranty / reusable.
Does it power? Probably very little? Conflict w/ Access Port? Many said so cause it oils the MAF sensor.

I prefer stock filter as it's good up to 300WHP smile


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#6 2005-06-21 17:01:29

SilverSubaab
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Registered: 2005-06-01
User Number: 128
Posts: 245

Re: K&N Air Filter

K&N filter - Just say no.  I'd rather keep my turbo clean as can be and just turn up the boost.  The stock intake is pretty decent.  I've had some form of intake, whether it was CAI, short ram, or just a K&N panel, and the 9-2X is staying stock in this area.  I've cleaned crap out of my intake/MAF in the past.  Just does not filter well enough.  Gains do not offset the risk/downside IMO.


07 Subaru WRX TR
WRB

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#7 2005-06-21 17:33:55

Wallew
Member
Registered: 2005-06-20
User Number: 288
Posts: 32

Re: K&N Air Filter

I've been using K&N filters on ALL our vehicles (which includes wifes current 05 Subbie Sport Wagon) and have NEVER had ANY of the issues listed above.  Granted, like any GOOD PRODUCT, you can mismaintenance it.  Just like ANY OTHER ITEM on your car.

But to say that adding a K&N airfilter is BAD for your turbo is (well to keep my language decent) JUST PLAIN INCORRECT.

BANKS uses K&N on ALL their turbo stuff.  So does MR. TURBO (Gale Banks) NOT know what he's doing?

Why don't one of you contact Banks Engineering OR K&N itself and talk to a tech person.  THEY will set you right on THIS SUBJECT.

K&N FILTERS - JUST SAY YES to THE BEST FILTER ON THE PLANET...  and NO I don't work for Banks OR K&N.  I just know horse hockey when I smell it.  And saying K&N is a BAD FILTER FOR YOUR AERO is just that.  HORSE HOCKEY.


I'm a Renaissance man, gunsmith, NRA certified firearms instructor, freelance photojournalist, chef, gardener, medic, computer whiz, philosopher, mechanic, bartender, janitor, and security specialist

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#8 2005-06-21 22:25:12

SilverSubaab
Member
Registered: 2005-06-01
User Number: 128
Posts: 245

Re: K&N Air Filter

To Wallew:

  Then run the darn K&N.  Sh*t.  This is a great board.  Everyone on here is apparently an expert on everything automotive.  How fortunate for us all.  I have searched on Subaru/WRX board for a while on intakes and in general they seem like bad news for the car.  As well, I did not say that every car that has ever had a K&N in gets damaged or runs poorly, or whatever.  I've had a few in cars I've owed, and the cars have run ok, but I have also cleaned sh*t out of my intake piping and off my MAF.  That is my experience, not a guess.  There is documented cases of the filters messing things up.  If you want to do it, then do it.  If you think K&N is the greatest thing, fine.  I never said it was a bad product, it just does not appear to be a great product considering all factors for our car w/ a turbo.  I'd rather my car last longer and ingest less crap in the engine.
  As far as "horse hockey"?  I was just trying to help.  Do what you want; I was just giving my experiences and my opinion based on those experiences and the info I have found.  I'm not trying to sell anything or direct anyone away from anything for personal gain.  This is a automotive chat board for people who share a similar interest and who I hope would want to help each other out.  Calm the F*ck down.  It's a filter.


07 Subaru WRX TR
WRB

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#9 2005-06-21 23:50:16

john_matrix
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From: Asheville, NC
Registered: 2005-06-06
User Number: 168
Posts: 23459

Re: K&N Air Filter

i just want the sticker so that I dont get the oil change guy hasslin me about changing the filter everytime I go in.big_smile

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#10 2005-06-22 07:30:01

WDEagle
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From: Fernandina Beach, FL
Registered: 2005-05-11
User Number: 7
Posts: 1427

Re: K&N Air Filter

I have a K&N filter on my Colorado ZQ8 and an aftermarket intake/filter on my Corvette.  I have, however, chosen not to run a K&N intake on our 92x.

WDEagle


Hers --------> 2005 Midnight Black Flat Black Pearl White Saab 92x Aero w/sport & 2016 Ultra White Lexus NX200t F Sport
Mine --------> 2004 Black Chevrolet Colorado ZQ8 2016 Lazer Blue Chevy Colorado Crew Cab
Ours --------> 2004 Millennium Yellow Chevrolet Corvette Coupe
Ours 2 ------> 1966 Arcadian Blue Ford Mustang Coupe

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#11 2005-06-22 07:36:48

SilverSubaab
Member
Registered: 2005-06-01
User Number: 128
Posts: 245

Re: K&N Air Filter

john_matrix wrote:

i just want the sticker so that I dont get the oil change guy hasslin me about changing the filter everytime I go in.big_smile

LOL  banana


07 Subaru WRX TR
WRB

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#12 2005-06-22 09:40:46

eurospeed
Will race for food.
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Registered: 2005-05-13
User Number: 29
Posts: 1099

Re: K&N Air Filter

Here's my take on using a K&N.

It's a decent filter, but it allows larger particles to pass through when clean (vs. a paper element filter), hence slightly more airflow.  The K&N only filters better than paper when it becomes dirty, i.e., dirt is filling the voids in the oiled cotton.  And as you guessed it, the flow is worse than clean paper when it is dirty.  In other words, if you want the best performance, make sure to clean the K&N on a regular basis.

I chose not to run a K&N and simply change my paper element filters more frequently.  If you live in a climate with sanded/salted roads or a generally dusty climate, I would avoid using a K&N.


EUROSPEED EUROSPEED EUROSPEED
saab 92x AERO ..:::::::.. driving banana

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#13 2005-06-22 16:10:46

Wallew
Member
Registered: 2005-06-20
User Number: 288
Posts: 32

Re: K&N Air Filter

We've lived in Denver, on and off for more than twenty years.

I've been using K&N filters for AT LEAST that long.

And sure, since all you folks here know so much more about turbos than GALE BANKS, a man who is know industry wide as Mr. Turbo, then sure, DON'T USE the K&N filter.

I just don't care.  But then, for those of you who WANT to use the best products out there, give Banks Engineering a call.  I'm sure they will be HAPPY to explain why the recommend K&N over plain paper filter.  I just got off the phone with them and they put K&N filters in MOST of their turbo kits.  Call them yourself, cause I know you folks would never believe me (troll, spammer, employee of Banks - I am NOT).

And I've NEVER had one problem with any of the engines in any of the vehicles I've owned over the years.

Having said that, I've been running a stripped filter (removed the foam cell covering) that blocks all large particles out of my Harley for ten years.  Just broke the upper end down about a year ago to replace two collapsed lifters (at 50k miles - fairly typical for lifter failure in Harleys) and I have had ZERO wear or any other problems.  After replacing all the lifters (4) and then a new set of rings, she's running better than ever.

And that's on an air cooled motorcycle...

And just so everyone is clear - your engine is nothing more than an air pump.  The MORE air it flows, the better it runs.  So go ahead and use those restrictive paper filters.  After all, the factory would never try and save a penny or two by putting a paper filter in when a K&N would be better for it now would they?

Last edited by Wallew (2005-06-22 16:14:07)


I'm a Renaissance man, gunsmith, NRA certified firearms instructor, freelance photojournalist, chef, gardener, medic, computer whiz, philosopher, mechanic, bartender, janitor, and security specialist

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#14 2005-06-22 17:37:25

eurospeed
Will race for food.
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Registered: 2005-05-13
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Posts: 1099

Re: K&N Air Filter

Wallew wrote:

Having said that, I've been running a stripped filter (removed the foam cell covering) that blocks all large particles out of my Harley for ten years.  Just broke the upper end down about a year ago to replace two collapsed lifters (at 50k miles - fairly typical for lifter failure in Harleys) and I have had ZERO wear or any other problems.  After replacing all the lifters (4) and then a new set of rings, she's running better than ever.

I take it you ride your Harley in the winter with sand and salt on the roads?


EUROSPEED EUROSPEED EUROSPEED
saab 92x AERO ..:::::::.. driving banana

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#15 2005-06-22 17:44:42

salaki
I love Pink...
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From: DFW & CGK
Registered: 2005-06-16
User Number: 237
Posts: 3072
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Re: K&N Air Filter

Wallew,

What happened man?
You got banned?

KNN or stock filter don't matter to me.
My STi dynoed 304 AWHP/314TQ (might be overrated but not much) w/ Stage 2 AcessPort.
And Yes. I am still using STock air filter.
Even those w/ APS 65mm CAI still make less or equal power than me on the same dyno.

Many tuners EJ20 / EJ25 proof that CAI or KNN, etc do not really add power until you go well above 300 WHP w/ FMIC
So why exposing yourselfs to MAF errors / other problems that EJ20/25 owners have experienced.

I'll probably change to another stock air filter when I hit 30K.
Why? I can buy one new for cheap.
I can even change every 15K miles.
Brand new, no headache if the oil messes up the MAF, etc.
It's OEM - Dealership won't bitch about it.

Last edited by salaki (2005-06-22 17:58:54)


AIRBAGS SAVE LIVES - AWD SAVES AIRBAGS
SAABIE: Saabaru Tecnica International - 92X Aero - World Rally Red tongue - Premium - Cold Weather - & more.

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#16 2005-06-22 18:33:03

eurospeed
Will race for food.
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Registered: 2005-05-13
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Posts: 1099

Re: K&N Air Filter

This is a nice study:  (plenty more like it)

MMmm...note the levels of dirt passed.

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm


EUROSPEED EUROSPEED EUROSPEED
saab 92x AERO ..:::::::.. driving banana

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#17 2005-06-23 00:45:38

yogi92x
Member
Registered: 2005-06-15
User Number: 228
Posts: 206

Re: K&N Air Filter

I posted this somewhere else here but dont remember where.  I have a FRAM Airhog in my wrx, i kinda just bought it because i was changing the oil so changed the filter at the same time, kind of an impulse buy.  ANyway it is very similar to the K and N from what i hear only cheaper.  I didnt notice any gain or loss in performance but what i did notice, was a little bit more turbo sound, especially at low RPM which made me very happy since i like the sound big_smile.  On that note, i will probably transfer the airhog to my 92x and put the 92x filter in the wrx when i sell it. UNLESS of course i notice a buildup of dirt in the airbox, but im not anticipating finding any in there.


2005 Black Aero Luxury and Cold big_smile


Other ride: 2006 Corvette Z06 mad

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#18 2005-06-23 05:53:17

KoRn
Member
Registered: 2005-06-03
User Number: 147
Posts: 23

Re: K&N Air Filter

Thanks to all for your comments

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#19 2005-06-23 08:44:36

Chris_K
It's not the heat, it's the humanity.
Registered: 2005-05-13
User Number: 24
Posts: 29

Re: K&N Air Filter

I'm with Eurospeed on this one.  Past the illistrious "pants-dyno" I have yet to see conclusive evidence for the positive on K&N, or any type of oiled-media air filters on stock to medium modified vehicles.  I have however seen more than just his link of articles pointing out the detrimental effects of using such a filter.  Yeah they sound kind of cool, but that's not enough to get me to buy one, again...(my last car had one, I took it off.)

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#20 2005-06-24 06:28:36

hotrod
Member
Registered: 2005-06-23
User Number: 345
Posts: 16

Re: K&N Air Filter

It is interesting to note on that study that at the bottom of the page is states:

To be consistent with common industry practice all filters were tested using PTI Course Test Dust. Course dust is more commonly used since it will produce higher % efficiency numbers.

Yet if you go up and look at the charts they explicitly state that the K&N 33-2135 and the AFE 72-90008 filters were tested with fine dust.


That would explain why the test results do not match up well with real world usage. The oiled cotton K&N filters were developed for use in Offroad racing. The stock filters (like the paper AC tested) which according to the tests should catch more dust and last longer in use would simply strangle the engines part way through the races. The K&N type filters would last for the entire race with little impact on engine performance. That real world experience is 180 degrees out of phase with these tests.

The bar charts are also a bit misleading --- graphics can very easily distort statistical info.

For example the top bar chart on filter effeciency gives the impression to the casual observer that the K&N is only about 25% as effecient as the AC filter, when in fact it compares 96.8% effeciency to the AC Delco's 99.93% effeciency.  96.8/99.93 = 99.75  in other words the difference in effeciency is negligable.


The ISO test is also a bit unrealistic in terms of its total dust loading. It may give a good representation of what you would see if you drove for hours behind another car on a dirt road at high speed but it is hardly representative of the real world.

The total dust load on the AC filter is 573.9 grams --- how many folks realize that is over a pound of dust.

I've put many an air filter on a many a car over the last 35 odd years of driving and work in repair shops and an air filter that is absolutely filty and strangling the engine it is on only has an ounce or so of dust on it.

Go home and measure out a pound of sugar or flour and see how big a pile it represents.

I've used K&N filters since they first came out and have put well over 150,000 miles on several engines using them. In one engine, when it was torn down for rebuild, the cylinder walls were so good and had such low wear I could have simply broken the glaze with a hone and put stock rings back in and reassembled it. The valve stems were also still within OEM specs.

The real world tells me that the K & N work just fine. If you do get a bit of oil buildup on your MAF sensor it takes all of 30 seconds to clean it with a can of spray brake cleaner--- about the time it would take to look at your OEM air filter to see if it needs replacing.


I live in a dusty environment and have spent many hours driving at high speed on dirt roads as well.

FWIW
Larry

Last edited by hotrod (2005-06-24 06:30:21)


2002 Impreza WRX  -- [email protected] @ 5800 ft on stock TD04L-13T turbo

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#21 2005-08-28 18:37:46

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: K&N Air Filter

eurospeed wrote:

This is a nice study:  (plenty more like it)

MMmm...note the levels of dirt passed.

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

You are refering to a "study" in a public server with no real reference to who did the study, etc.  How can people believe 100% in something like this?  I am an engineer and a scientist and believing studies by Joe Schmo in the internet is not my cup of tea.  And assuming everything is kosher, even factual data and graphs can be shown in ways to make differences worse or better, depending on the bias of the author.  Also statistically differences between 100 air filters from one brand can be worse than the differences between 100 air filters from different brands...
Who can say if the difference in filter efficiencies actually harms your car?

     My other two cars have K&N filters (98 Mustang GT-75k miles & 96 Eagle Talon Turbo AWD-115k miles) and I am a big fan of them.  I used an OBDII program to log and prove that the Talon's amount of air going into the engine (lbs/min) increased 44% going from the stock panel filter to the K&N 'under the hood' open cone filter.  On a turbo car that is HUGE!  On my Mustang I used a big cone filter for a pickup application and jury-rigged it unto the intake.  It gave me really good gains in the middle and high rpm range.  It also made me lose power at the low end because of the lower 'intake air velocity'.  Once I replaced the intake system with smaller-diameter piping and compensated for this it also gave me good gains in the low rpm range.  Basically I love these filters and in practice they have performed very good indeed.

Last edited by Richardito (2005-08-28 18:41:41)

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#22 2005-08-28 20:22:24

BSlickOH
2005 9-2X Aero Silver
From: Loveland, OH
Registered: 2005-06-20
User Number: 286
Posts: 439
Website

Re: K&N Air Filter

So, within the context of a single post, you want us to disregard something from "Joe Schmo," yet believe your own anecdotal evidence?

Of course it lets more air through; it isn't filtering as well.  That's pretty much how they all work.


1998 Acura Integra LS

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#23 2005-08-28 20:40:19

Scargo
Freely Inhabiting the Space I'm In
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From: Hancock, NY
Registered: 2005-06-15
User Number: 227
Posts: 14179

Re: K&N Air Filter

Richardito wrote:

eurospeed wrote:

This is a nice study:  (plenty more like it)

MMmm...note the levels of dirt passed.

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

You are refering to a "study" in a public server with no real reference to who did the study, etc.  How can people believe 100% in something like this?  I am an engineer and a scientist and believing studies by Joe Schmo in the internet is not my cup of tea.  And assuming everything is kosher, even factual data and graphs can be shown in ways to make differences worse or better, depending on the bias of the author.  Also statistically differences between 100 air filters from one brand can be worse than the differences between 100 air filters from different brands...
Who can say if the difference in filter efficiencies actually harms your car?

     My other two cars have K&N filters (98 Mustang GT-75k miles & 96 Eagle Talon Turbo AWD-115k miles) and I am a big fan of them.  I used an OBDII program to log and prove that the Talon's amount of air going into the engine (lbs/min) increased 44% going from the stock panel filter to the K&N 'under the hood' open cone filter.  On a turbo car that is HUGE!  On my Mustang I used a big cone filter for a pickup application and jury-rigged it unto the intake.  It gave me really good gains in the middle and high rpm range.  It also made me lose power at the low end because of the lower 'intake air velocity'.  Once I replaced the intake system with smaller-diameter piping and compensated for this it also gave me good gains in the low rpm range.  Basically I love these filters and in practice they have performed very good indeed.

Although I can concur on your emperical evidence (on my normally aspirated Solo2 GTi and my turbo Audi 200quattro) of performance gains (including use of the boost/vac gauge on my 200) I've also emperically noted
the increase of dirt that was passed, particularly in the 200Q's intake tract compared to the OEM filter (the GTi
doesn't flow enough and didn't drive enough miles to notice the difference). Henceforth, although I like the
performance edge of the K&N's (freer revs in the GTi, quicker spool up in the Audi, both documentable), I've decided it's not worth it.  I'm back to paper filters.

Scargo


1995.5 Audi //S6, Black/Ecru; MRC Stage 2, Eibach/Bilstein, RS2 BBK, HID's, Eurotails
2005 Saab 9-2X Aero Satin Grey; Cobb STX tune/Cobb 25 mm FSB, 22mm solid adj RSB/H6 upgrade/Noltec Camber Plates/STI Pinks, Koni Inserts/Whiteline Rear Stress Bar/Izixhood/Stromung DP, Crucial HF Kitty, STi catback, Hella MicroDE fogs, color keyed/polished roof rails.

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#24 2005-08-29 23:07:28

coalburner400
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From: Shitcago
Registered: 2005-07-29
User Number: 626
Posts: 705

Re: K&N Air Filter

I have experience with both Banks and K&N.

I would run some of banks performance stuff, but many I would not run on a daily driver.  Same goes for the K&N.  The performance gains sacrifice long term reliability on both accounts.
No doubt K&N flows better than paper media, but it does so at a cost.  K&N can tell you that it's a non-sacrifice since smaller particles don't hurt your engine - but I don't buy it.  Its for short lived track motors in my opinion.  ...just my opinion, and I do run a K&N on the firebird  smile

confused Anyone have experience with "alternative media" filters other than K&N?

confused Any true numbers to vouch for the performance?

I'm looking for good flow with superior filtration.  You know, "the cake and eat it too". wink

I've found:
http://www.greenfilterusa.com/
http://go.mrgasket.com/default.aspx?BrandID=11

Nothing seems conclusive at this point.  I do have a need for more airflow, but I don't trust K&N.  I would like something scientific with a comparison matrix between filter media types.  I would reconsider K&N if I had conclusive evidence to prove it's worth.

Thanks folks


92x Aero Satin Gray Metallic  | Sport | Cold
68 Firebird 400
01 Cummins powered Ram - rolled, RIP sad
08 Cummins powered Ram

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#25 2005-08-30 10:14:37

STi292x
Member
Registered: 2005-06-29
User Number: 388
Posts: 58

Re: K&N Air Filter

There's one tuner that I have put much trust in because they are Subaru specific (which applies to 9-2x also), and that's Cobb. A lot of people here have put enough trust in them to use there flagship mod - the AccessPort - which can technically be a bigger risk than a filter! But, most importantly - and my point - is that they tune, test with, and sell this very product being argued, the K&N filter!
I think if there were any real serious risks, or long term effects, on our engines with this filter they would be the first to be against using it. For this very reason I have no worries having a K&N in my car along with the AP and every other mod I've done. Besides, if we all worry this much about a simple mod then we shouldn't mod our cars at all, and run the cars as the manufacturer intended it to!  tongue

So, the bottom line, enjoy it if you already have it in your car 'cause it's not gonna' kill it!  cool


'05 black 92x Aero with cold package (all my STi's goodies and then some!!)

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