[cochran]

Is the K&N filter worth purchasing? I've searched around and seem to have found mixed reviews. Some have even said it's potentially worse than the stock air filter..?

[NA55]

I've had good results and was able to put down 442 whp FBO on e60..

[MAN15H]

I've also read reviews that say it’s not really worth it.
I think that as it sits in the air box for a lot longer than the stock filter and apparently, according to the manufacturer, allows greater airflow than stock and can be cleaned and put back in the car it can’t be that bad...
It also didn’t really cost that much more and as you don’t have to throw it away and buy a new one its eco-friendly but does it have any negative effects on the engine..?
I’ve had one in my car for quite some time now and never noticed any issues.
Would like to hear some real expert’s views though.
Anyone ever dyno a car pre and post installation or carried out other tests to see if it is actually any good..?

[=C=]

Originally Posted by cochran

Is the K&N filter worth purchasing? I've searched around and seem to have found mixed reviews. Some have even said it's potentially worse than the stock air filter..?

Worse than stock filter? Huh, what forums have you been to that said this...


The K&N drop in filter is a lot better than the stock paper filter.

[stanlalee]

Who do you have to lose. By the time you've bought an OEM replacement several times you've spent the same money. You aren't going to feel much but you aren't going to feel much with a dci either (you'll hear a lot more)

[TrollToll]

Originally Posted by cochran

Is the K&N filter worth purchasing? I've searched around and seem to have found mixed reviews. Some have even said it's potentially worse than the stock air filter..?

It does flow better but not by much. The reason that people avoid it is because the cotton gauze media doesn't capture as much dirt as the oem filter does. So basically you are allowing more contaminants into your engine and not gaining much, if anything, from it. There are many tests on K&N filters where they demonstrate how much stuff actually gets past them.

Edit: there are tons of different tests and sources, but here is a link to one of them.
http://www.nicoclub.com/archives/kn-vs-oem-filter.html

[Jaronbwall]

Not that it matters but I picked one up in the for sale section for $30. I noticed an increase in mpg's but only on highway driving.

[sudo4re]

Originally Posted by Yournamehere90

It does flow better but not by much. The reason that people avoid it is because the cotton gauze media doesn't capture as much dirt as the oem filter does. So basically you are allowing more contaminants into your engine and not gaining much, if anything, from it. There are many tests on K&N filters where they demonstrate how much stuff actually gets past them.

Edit: there are tons of different tests and sources, but here is a link to one of them.
http://www.nicoclub.com/archives/kn-vs-oem-filter.html

+1.

It makes sense because since the K&N filter occupied the same space as the stock filter and unless they have a magical way to greatly increased the filtration surface area, the only way for the K&N filter to flow greater air volume than the stock filter is to make the filter material less dense ie: larger openings thus allowing more particulates to pass thru and into the intake tracts.

[Jeff@TopGearSolutions]

K&N should be done at a minimum. The stock intake is very restrictive.

Even the best intake on this platform won't allow for the wow factor in terms of gains but in the effort to improve efficiency the drop in filter helps

[Rosetta Stoned]

Yearly oem filter changes costs probably more than buying a K&N and continually cleaning it, depending on length of ownership. Don't think there's any performance gains. That said, I put a DCI on mine cause I like the sound of it but knowing that it likely doesn't do much other than that.

[Rory]

I was thinking about a drop in , but Ive seen quite a lot of testing over the years showing they dont flow as much as a normal paper filter can.

I've had them in 2 previous cars to try them, albeit non turbo cars and felt absolutely no difference.

[Jeff@TopGearSolutions]

The differences can easily be measured by looking at your wastegate duty cycles.

If they drop after the intake change, you've improved efficiency.

There has been testing done by members but I'm talking 6+ years ago. The consensus was then what it still is today. You need to open up the restriction of the stock intake with a drop in or go to a DCI or other box that has more flow.

Breathing through the stock intake is like breathing through a straw for this car.

[mike@x-ph.com]

Originally Posted by cochran

Is the K&N filter worth purchasing? I've searched around and seem to have found mixed reviews. Some have even said it's potentially worse than the stock air filter..?

Yes it is worth it

Dont expect huge performance increase but this filter does a great job improving air flow at a cheap price

[Rory]

Originally Posted by Jeff@TopGearSolutions

The differences can easily be measured by looking at your wastegate duty cycles.

If they drop after the intake change, you've improved efficiency.

Thats a good point, I might take the airbox lid off and drive it back to back with the lid on and compare for a bit of fun, just to see if the box itself is a problem at my level of tune. If I have some free time with nothing better to do that is lol

[Aqid]

Originally Posted by Jeff@TopGearSolutions

The differences can easily be measured by looking at your wastegate duty cycles.

If they drop after the intake change, you've improved efficiency.

There has been testing done by members but I'm talking 6+ years ago. The consensus was then what it still is today. You need to open up the restriction of the stock intake with a drop in or go to a DCI or other box that has more flow.

Breathing through the stock intake is like breathing through a straw for this car.

That's pretty much how I did it too. Didn't want DCI for personal reasons (I'm sure they perform fine, I just don't like the placement, looks and sound of them). So I used the K&N drop in and opened up the stock airbox on the side ("Mr5. style"). It's a cheap alternative to more expensive CAI's.

[Rory]

Originally Posted by Aqid

That's pretty much how I did it too. Didn't want DCI for personal reasons (I'm sure they perform fine, I just don't like the placement, looks and sound of them). So I used the K&N drop in and opened up the stock airbox on the side ("Mr5. style"). It's a cheap alternative to more expensive CAI's.

I know what you mean about the look of DCI , its not really to my taste either... but to be fair I dont stand around with my bonnet ( hood!! ) open saying hey look at this.

Did you notice any difference with your mr 5 style intake?

The map Im running is round about 15psi max I believe so I dont know how much of a restriction the box is. I suspect it might be getting away with it just now, much more boost and it might be a bottleneck.

[BQTuning]

Common sense test

Take the stock filter put it up to a light or sun and do the same with K&N and see which more light passes through

[JustDriveIt]

I was told NOT to do this with the stock air filter housing because there is a charcoal secondary non-replaceable filter and the K&N by being "less restrictive" allows more contaminates that clog up the charcoal filter which cannot be replaced.

The charcoal filter is for trapping fuel fumes after the car is turned off for EPA standards.

Of course you can cut it out if you want to permanently damage the stock Air box.

For NA engines, a drop in may benefit, but not a bi-turbo. DCI at the least is needed to actually make an improvement.

[TrollToll]

Originally Posted by JustDriveIt

I was told NOT to do this with the stock air filter housing because there is a charcoal secondary non-replaceable filter and the K&N by being "less restrictive" allows more contaminates that clog up the charcoal filter which cannot be replaced.

The charcoal filter is for trapping fuel fumes after the car is turned off for EPA standards.

Of course you can cut it out if you want to permanently damage the stock Air box.

For NA engines, a drop in may benefit, but not a bi-turbo. DCI at the least is needed to actually make an improvement.

I believe that you are referring to the intake system on v8 engines. I've never seen an n54 with a secondary filter.

[Aqid]

Originally Posted by Rory

I know what you mean about the look of DCI , its not really to my taste either... but to be fair I dont stand around with my bonnet ( hood!! ) open saying hey look at this.

Did you notice any difference with your mr 5 style intake?

The map Im running is round about 15psi max I believe so I dont know how much of a restriction the box is. I suspect it might be getting away with it just now, much more boost and it might be a bottleneck.

I'm only running 12 as I'm on stage 1, so it was more in preparation of things to come. Honestly I could barely tell, but I'm sure if I would have logged before and after (which people have done with the same setup) the numbers would show it. It should definitely increase efficiency.

[JustDriveIt]

Originally Posted by Yournamehere90

I believe that you are referring to the intake system on v8 engines. I've never seen an n54 with a secondary filter.

Nah, it's all over this forum and there's a DIY for it. If you do a K&N Drop in filter you MUST do the charcoal delete mod with it or you are going to have issues. It's a lot harder to do than the M5's as well, it requires a dremel or equivalent.

[TrollToll]

Originally Posted by JustDriveIt

Nah, it's all over this forum and there's a DIY for it. If you do a K&N Drop in filter you MUST do the charcoal delete mod with it or you are going to have issues. It's a lot harder to do than the M5's as well, it requires a dremel or equivalent.

Many other engines have it, but I've never seen one on the n54. Neither my 1 or 5 series has it. If you do have one, please post a picture.