Performance airfilters are a waste of time

[netercol]

http://www.bobistheoilguy.com/airfilter/airtest1.htm

http://home.roadrunner.com/~jbplock/ISO5011/SPICER.htm

very good read..

for me the main point is that a clean paper filter of the right size flows very very near to a cotton gauge (k&n, not chinese fleamarket filters) but definitively filters better.
downside to paper is ofc that flow falls dramatic as it gets dirty..

 

[ed_z]

Yes they do make a difference if you have the correct upgrades on your car and depending on what type of setup and config your car is.

AFE dual intake is what i have and was in the states when i looked at one of the M's Turner Motorsport were doing and tested on the dyno made 12wkw more, you might say but that is not alot and i might agree with you but AFE come with the scoops as well that mount under the kidneys and when these guys tested it on the road at 60km/h they were seeing gains of over 20wkw vs HP readings calibrated to variance in speed and time taken from certain speeds in different gears as these cars do not get enough air as you would on the road at a dyno. So for my application for sure, if you want a throaty noise from your car drill holes in the airbox:roflol:

 

[moranor@axis]

the Road runner test reveals i am very wrong about the K&N but AFE which is also oiled cotton performed very well

maybe there is something that skewed the K&N results in that test? if not AFE is most definitely the way to go :rollsmile:

 

[ed_z]

Ok also on the Savspeed Z4 M Turbo which is doing close on a 1000hp and with this application it's necessity as you need a especially robust strong filter otherwise the amount of air that Turbo sucks collapses the filter and in a single WOT run its buggered. This is why I said specific applications it can work but not every car. Also on my E92 M3 it made the car slower by half a car next to my buddies M3 and we put back to stock filter cars were the same again. If you do full pipe, sw and filter there will be gains to be had out of a filter.

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the Road runner test reveals i am very wrong about the K&N but AFE which is also oiled cotton performed very well

maybe there is something that skewed the K&N results in that test? if not AFE is most definitely the way to go :rollsmile:

KnN is a brilliant filter I'm not sure I agree with that test bud?!

 

[netercol]

lol.. i did not do the testing

i do use k&n filters myself, like you said, they do have their place and uses.. space constraints, robust , offroad conditions..

but i reckon its logical if you think about it for a second.. a small hole will keep bigger particles out, but flow less air.. a bigger hole will keep less particles out but flow more air.. a simple tradeoff..

the one thing i have never been able to find is some form of long term data showing how much more actual engine wear can be attributed to less effective air filtration vs more effective.. now that would be interesting..

just fyi, k&n's own iso tests show predictably different results than the private tests.. guess it a never ending game

 

[moranor@axis]

but cotton filters use oil to trap the dust so the bigger whole story dose no quite work

foam filters have huge holes yet they are used extensively for off road applications :rollsmile:

the US use K&N filters to protect the turbine engines of their apache helicopters in Iraq

 

[hotchocolate]

I have had CAI's on all of my cars and I can say that every car that I will purchase in future for myself will have the standard airbox removed and a CAI installed. In all of my cars I got better performance and better fuel consumption.

By changing to a CAI on my MINI, I dropped my average fuel consumption from 8.6l/100km to 8.1l/100km. Then there is the performance and the sound which I fall in love with every morning when I drive her to work.

CAI's and cone filters win hands down in everyday testing.

 

[netercol]

but cotton filters use oil to trap the dust so the bigger whole story dose no quite work

foam filters have huge holes yet they are used extensively for off road applications :rollsmile:

the US use K&N filters to protect the turbine engines of their apache helicopters in Iraq

all true.. but i still think the general idea holds true.. i mean a perfect filter lets no air through

By changing to a CAI on my MINI, I dropped my average fuel consumption from 8.6l/100km to 8.1l/100km

sorry mate, i simply cannot agree with this part.. if that was the case, cars would come with these fitted straight from the factory..

 

[DieselFan]

Well my K&N drop in, is arriving any minute now. Just if this damn courier could find my place :fencelook:

Also getting my car back from a service today :thumbs:

Soooo the courier calls me and he's like "I cant find your address on the GPS"
So we try to meet somewhere, after 2 hours of talking on the phone saying he cant find this area im talking about and i cant find this area he's talking about. I'm like "Fuck bru, I'm at the bottom of table mountain, where the hell are you".

He starts laughing, as he's in joburg. Stupid autostyle had put Joburg on the Box and not cape town. Morons. Wasting my time and money.

 

[hotchocolate]

Quote:
By changing to a CAI on my MINI, I dropped my average fuel consumption from 8.6l/100km to 8.1l/100km

sorry mate, i simply cannot agree with this part.. if that was the case, cars would come with these fitted straight from the factory..

Its not about agreeing dude, what I am telling you is a fact which I have witnessed on a daily basis for the past 10 years.

The only reason they are not fitted as standard parts from the factory is because of the noise and emission laws world wide. Not every granny wants a noisy car because it consumes less fuel. In some countries like Oz and Canada, these filters are prohibited for that exact reason, noise pollution laws.

Each to their own I guess. This will be a topic that can only be answered by personal trial and error.

 

[netercol]

Quote:
By changing to a CAI on my MINI, I dropped my average fuel consumption from 8.6l/100km to 8.1l/100km

sorry mate, i simply cannot agree with this part.. if that was the case, cars would come with these fitted straight from the factory..

Its not about agreeing dude, what I am telling you is a fact which I have witnessed on a daily basis for the past 10 years.

The only reason they are not fitted as standard parts from the factory is because of the noise and emission laws world wide. Not every granny wants a noisy car because it consumes less fuel. In some countries like Oz and Canada, these filters are prohibited for that exact reason, noise pollution laws.

Each to their own I guess. This will be a topic that can only be answered by personal trial and error.

whether you say its fact does not make it so, nor does your empirical observations make it so.
but like you say, each to his own..

 

[Zack]

I guess at the end of it day it boils down to either it works for your car or it doesn't. :dunno:

 

[herr bmw]

just a question.

if k&n is so crap then why when i watched a you tube video on the brabus v12 does it have k&n in and why do bmw provide this in the m range?

 

[netercol]

nobody said a k&n filter is crap..
people just need to understand why they are changing to a k&n and the compromises involved..

just some info as to why milage gain claims with cai's and airfilters are baseless..

from this report's conclusions

"Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a decrease in fuel economy with increasing restriction. However, the level of restriction required to cause a substantial (10–15%) decrease in fuel economy (such as that cited in the literature3,4) was so severe that the vehicle was almost undrivable. Acceleration performance on all vehicles was improved with a clean air filter"

http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf

will a k&n give a small increase in power? yes.
will it give improved throttle response? probably.
does it filter as well as a paper filter? nope.
is it a lifetime filter? yes.
will it increase fuel effieciancy? nope
will a k&n cause more engine wear over a long period due to less effieciant filtration? unknown..

 

[bimmer330]

My biggest concern is filtration effeciency.
Some of these filters only keep out bigger birds and stones.
Small birds and smaller stones might get through

Stop talking kak man!

Jirre, don't you have a sense of humour? It was a bit tongue in cheek, and overly exaggerated. But still valid.
What micron are the OEM filter rated at, and also the K&N and other after market filters?
If an OEM is 3 micron, and an aftermarket 5 micron, then surely there would slip more dust particles through. And if you neglect the maintenance on your aftermarket filter, or clean it with an aircompressor, you're gonna have trouble.

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BTW, the micron figures mentioned above is not fact, only numbers to state my point. I will try to get correct figures...

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Agree, No sence of humor the way I understand.

 

[kabal]

replacement filter improves fuel economy AND increase performance? :biglol:
should wrap some magnets around the fuel lines too, and then sell to the car manufacturers -> profit :fencelook:

 

[Jerez]

Wont these work better in conjuction witha remap.To be honest,Ive been trying to make my e 92 a bit better but induction kits,power pulleys and remaps just seem to be gimmicks for an adition 20/30 bhp.

 

[moranor@axis]

NA car the best bang for buck is:

Exhaust
Filter
Tune
and shorter gear ratio diff

after that you need to start spending big money on NA or boost

 

[SP33DYV]

NA car the best bang for buck is:

Exhaust
Filter
Tune
and shorter gear ratio diff

after that you need to start spending big money on NA or boost

I only agree with the shorter differential ratio. :sorry:
Filter, tune and exhaust will not make a huge difference on a N/A engine. Ask Coisman. We tested this. Admittedly, we need to test in gear acceleration as well, but from the line... :nonono:
You want to make a big difference on a N/A car you need a set of decent cams and a flowed head with the addition of altering the compression (ie skim the head). All of this coupled with the above will give bigger gains, but will cost a lot. Just my 2 cents.

 

[moranor@axis]

NA car the best bang for buck is:

Exhaust
Filter
Tune
and shorter gear ratio diff

after that you need to start spending big money on NA or boost

I only agree with the shorter differential ratio. :sorry:
Filter, tune and exhaust will not make a huge difference on a N/A engine. Ask Coisman. We tested this. Admittedly, we need to test in gear acceleration as well, but from the line... :nonono:
You want to make a big difference on a N/A car you need a set of decent cams and a flowed head with the addition of altering the compression (ie skim the head). All of this coupled with the above will give bigger gains, but will cost a lot. Just my 2 cents.

the shorter ratio multiplys the torque the engine gives so the small gain to be had with the other mods becomes quite alot bigger with the ratio change

but as you said the gains are minimal compared to cams ect... in the end its just cheaper to go for boost...