Something interesting came up in one of my CTI courses... the instructor mentioned that K&N filters are worse than the stock filters in respects of protecting the engine.

Now that I think back on it some, it makes absolute sense that "free flowing" air filters would not be as effective in filtering out particles, but in return provide us with an increase in power.

So my question is, is it worth the risk of increasing engine wear? or do you guys simply just replace them more often?

 

Well, you dont replace a k&n filter, you clean it. I did hear that they filter better when theyr dirty. As for increasing engine wear, ive never heard that before...

 

The word I get from an OEM calibrator is that you are correct -- the K&N filters don't generally filter out particles as fine as those trapped by the OEM paper elements. It is a tradeoff, as you suspected. One thing to remember about flow rates is that the overall flow won't increase appreciably until you fix the greatest restriction. For example, if the catalytic converter is the greatest restriction in the gas flow path (and it often is), adding a free flow air cleaner may not help much. In this guy's testing on a brand X performance car, the K&N filter did flow better but provided no measurable power increase because of other restrictions in the system.

As for the decrease in filtration -- I don't know if anybody has good, useful data on the effects.

Despite all this, I am using a K&N style filter (mine's an S&B) because they work fairly well, they're easy to package in custom applications, and they can be washed, oiled, and re-used.

 

i think if the increased wear were a large factor or even a major concern then the company may not still be in business. i've used k&n air filters on a number of applications for a number of years with good results. it does make sense that perhaps the filters filtering abilities would suffer slightly to the better air flow design.

 

Here's an interesting test done by a fellow gear head...

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

http://www.bobistheoilguy.com/airfilter/airtest3.htm

 

AWESOME read!! seems the best filter was the oem filter..makes me wonder how much damage that dirt is actually doing when using the k&n...

 

That's fascinating. Let's just say I'm glad I decided not to drop $90 on a K&N setup just yet.

 

Yeah, this has made me wonder if I want to just use my stock S4 Airbox rather than using a cold air style intake system...

 

I have a KN drop in filter on my SE and have used this for years in all of my SE's with no issues.

However I use a trueflow air filter in my Dodge truck.

Here is some info.

http://www.twoguysgarage.com/forum/s...ead.php?t=7244