Hey guys are K&N drop in filters for the turbo worth it.

are there any advantages on using it over the stock paper element one?

thanks

 

i dropped it in my '04c4s and found the engine to sound more smooth and easier on the ears

 

a year or so ago, someone on this site tested with a mass air flow meter OEM vs. K&N. I believe the results were that the K&N was actually more restrictive.

Anyone remember that string? I searched but their are too many for me to sift through

 

I'm running a BMC no problems so far and looks different, as for difference in performance ???

 

Go with BMC, less oil and less chance of cloggin the MAF. We used to run K&N's till customers started having problems with MAF's and immediatly switched to BMC and have had no problems!! I made the switch in my car (from K&N to BMC) and though I felt no difference my mind was happy to not think about a potential problem
Evan

 

Here's a scientific looking test, with a possible anti K&N bias. http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm
I remember a member of this forum doing a test using a shop vac hooked up to a turbo aif filter housing. He calculated the airflow using a very sensitive pressure drop meter. The K&N flowed about 1% less than a new OEM paper filter.
If you look at the stock filter it has a lot of very closely spaced pleats - lots of surface area. I think the stock filter is excellent.

 

i cant believe the kn filter flows less than a new oem filter...i always thought kn filters were great...switched all my cars with them

 

well they also say the K&N's need to break in. I read a thread somewhere saying they aren't fully broken in till about 10K or so. Which explains why people are having problems w/ the oil dripping and clogging up sensors.

 

the oil doesn't drip and clog the sensor. it is sucked off the element and sticks to the wire in the MAF sensor. the wire heats and burns the oil but leaves a residue that builds over time and makes the sensor less and less acurate until it fails. if your filter is dripping oil, you are surely to have serious issues....

-dw

 

I've seen tests done on the internet that say the same thing. Also, I heard the same thing over on the BMW Forums.

IMO, the K&N has a lower surface area (less pleats) than an OEM paper filter which leads to lower air flow.

- KJ

 

Totally disagree. Think of it this way...Take the filter frame with no material. One frame, you cram as many paper pleats as you can, the other, use the same density paper and lie it flat across the frame. One layer, no pleats. Just because there is more paper surface area, it does not imply that air will flow through it quicker(greater volume). More pleats will capture more particles, but will be more restrictive than a single sheet of the same density material.

Here's a good test. Try breathing through one layer of a bed sheet, then fold a few layers over and try to breath. I think you will find breathing easier through one layer than multiple layers. True, there's more surface area...but it's harder to breath.

 

Joe,

Don't buy it.... not worth it imo... even though its like $40.... the stock paper filter works best.... You know how critical i am about aftermarket products. I had originally bought the cold air system but ended up returning it after talking to some porsche techs. Someone did do a dyno on this and the results were negligable. It might be beneficial if you used it in conjunction with other engine mods but then again that's questionable. And, the paper works better at trapping dirt.

 

True, but you have to consider that the less surface area on the K&N will actually get clogged faster and will required more attention and cleaning. A paper filter does have more surface area but as dirt builds up, it keeps air flow more consistent throughout the life of the filter. K&N have noticeable difference in terms of sound and maybe initial performance but it drops off rather quickly and it doesn't trap dirt as well as stock paper filters. In addition, cleaning the filter becomes an art as you have to be vigilant in how much oil to spray onto the filter(most people put to much and it ends messin up air sensors, etc etc) , then you have to let it dry, then you have to put it back on the car.

With that said, I've been using K&N filter material on most of my cars (except the Porsche) because some airboxes are more restrictive than others and the K&N gives it that extra "kick" but the downside is that they get dirty fast and they require extra attention.

As for Porsche, the car/engine has been efficiently designed in terms of intake and a K&N filter will not noticeably improve the car. It will just be more of a hassle imo. However, if a car is already taken on engine modification.. then it may help and the extra attention wouldn't be an issue since the car would already require extra attention.

 

I totally agree with Curves4S. I don't see how a K&N filter is going to do a better job than the factory element. Unless it's part of a total package, I wouldn't bother installing anything but the factory filter.

 

What explains the free-er revving accelerator when going from stock to K&N for ie??? It is definately noticeable that when you get off the throttle, the revs fall quicker than they did with the stocker. I have noticed it on a few cars. I am not saying there is necessarily an hp increase, but throttle response, to me, seems to improve. That is an important benefit, imo