Your Thoughts on the use of K&N filter?
 

I wanted to get some feedback on the use/issues with K&N Filters. I was doing some research on replacing my MAF and I came across people saying that K&N Filters (If using them) are one of the issue that cause the MAF to start acting up due to the oil from the filter?

Anyone can confirm or dispute this claim or offer alternative to these filters?

thx :dunno:

The K&N filter uses oil on the foam to help filter. Too much oil can damage the MAF. It is well documented that it can happen. When the oil is properly applied, ie not too much, that specific problem can be avoided. Note that the filtering efficiency depends on the oil being properly applied. Also, the filter holds less dirt, ie it gets clogged more easily, so servicing needs to be done more often than with an OE filter.

The second potential problem is codes being thrown. It can happen. It is usually related to vacuum leaks.

The bigger questions in my mind are:

1) Why would you want less filtering capability? Lots of tests show that the K&N filter isn't as efficient at removing dirt. If you don't care about the filtering, just take the filter out. That is the lowest possible restriction, although it will be bad for your engine to ingest dirt.

2) Why worry about the minimal amount of restriction caused by a functioning air filter? It is completely irrelevant in terms of power production.

Some additional reading if you like. Follow the links here:

http://www.xoutpost.com/794434-post4.html

Edit: I checked the links in that post, and one is broken. Here is another link to the Duramax filter test with graphs of K&N filter efficiency compared to an OE:

Aftermarket Air Intakes/Filters - Do They Work? - Diesel Place : Chevrolet and GMC Diesel Truck Forums

Thanks JCL....very informative feedback.

I've had one fitted for 6 years without any trouble...

Note that the review link was for a diesel truck site. Diesels run at lower RPM than gasoline engines, and airflow is less crucial at lower RPM. My Boxster @ 7500RPM is sucking a lot more air than my X5 @ 5000RPM.

I don't see any reason to run a K&N filter in a diesel X5. If my X5 was gasoline, I'd check the CFM rating of the OEM filter vs. the aftermarket filter, then find out what the CFM requirements of the engine are at max RPM, and THEN decide if the K&N was worth the cash. In almost all cases, it's probably not worth it.

I run a K&N in my Corvette, but I also have a hacked airbox, free-flowing exhaust, and long-tube headers, so the motor can actually make use of the additional airflow. Switching to a different air filter without making any changes to the rest of the intake/exhaust system is, once again IMO, a waste.

Yeah, I used the diesel engine filter test because it is good comparative data. Engines are just air pumps, whether they are compression ignition or spark ignition. And those diesels have more displacement, as well as a lot of boost, resulting in high airflow requirements regardless of peak rpm. That is why the diesel truck owners spend a lot of time discussing intake modifications and filter efficiency, and conducting tests such as this one. Building on your point about exhaust flows correlating to intake flows, that is why diesel pickups have large diameter exhaust systems, because they are flowing so much.

Good point about the larger-displacement diesel engines... I was, of course, thinking of MY diesel, because I'm a self-centered BMW owner. :D

To answer the original poster's question (again, since I got carried away due to my self-centered BMW driver ego... heh) - you won't see any perceptible gain from the K&N. While a new properly oiled filter won't foul your MAF, recharging it yourself and doing it wrong often does. Spending additional money that may wind up costing you even more money - for no perceptible change except the addition of a K&N sticker - isn't worth it.

Replacing the soiled OEM filter with a new OEM filter is a good alternative.

:iagree: 100%

Waste of money.

So don't waste your money.

:iagree:. Waste of money.