K&N air filters?

[Kestral]

I installed a K&N air filter on my 2012 Pathy this spring and the truck runs fine with it no difference from the stock Nissan filters in power from what I see not that I was expecting anything. Some say they are fine to use while others say they let in more dirt? I like the fact I can clean it out every 50,000 miles and re use it. Anyone here use one in there R51?

[smj999smj]

A lot of the talk about K&N filters letting more dirt pass through was passed on the "Spicer Air Filter Test," which tested several different air filters using a Duramax engine. You can probably still find it if you do a bit of Google searching. One of the biggest issues I ran into with them when working for Nissan was the oil used on the filter. It would coat the hotwire of the mass air sensor, which would cause incorrect readings and cause the engine to run poorly. Generally speaking, in order for a cloth type filter to be any more beneficial than a paper conventional filter, it has to be less restrictive for the given the amount of airflow entering the engine. For most driving conditions that street driven vehicles experience, paper filters do an excellent job, usually as well as any cloth filter when it comes to restriction (or lack of), and a better job of filtering out dirt. It's typically at high RPM conditions, like racing, when the cloth filter may show an advantage over the paper filters in terms of restriction. So, unless you are replacing the factory air box with an aftermarket box that has a much better design in terms of airflow and/or cooler air which is denser, than simply switching to a cloth filter will usually not yield any performance gains...and still not have the filtering capability of the paper filter.

[eieio]

A lot of the talk about K&N filters letting more dirt pass through was passed on the "Spicer Air Filter Test," which tested several different air filters using a Duramax engine. You can probably still find it if you do a bit of Google searching. One of the biggest issues I ran into with them when working for Nissan was the oil used on the filter. It would coat the hotwire of the mass air sensor, which would cause incorrect readings and cause the engine to run poorly. Generally speaking, in order for a cloth type filter to be any more beneficial than a paper conventional filter, it has to be less restrictive for the given the amount of airflow entering the engine. For most driving conditions that street driven vehicles experience, paper filters do an excellent job, usually as well as any cloth filter when it comes to restriction (or lack of), and a better job of filtering out dirt. It's typically at high RPM conditions, like racing, when the cloth filter may show an advantage over the paper filters in terms of restriction. So, unless you are replacing the factory air box with an aftermarket box that has a much better design in terms of airflow and/or cooler air which is denser, than simply switching to a cloth filter will usually not yield any performance gains...and still not have the filtering capability of the paper filter.

I wish we had a "like" button!

[Kestral]

You bring up some real good points SMJ I was a little worried about the oil on the K&N filter when I installed it there was a great deal of oil on it and it did concern me. I think I will run down to my local Nissan dealer today and pick up a factory filter just to play it safe.

[labsy]

I switched to K&N cone filter some 6 months ago, and I had to remove the whole OEM airfilter box out to make place for new cone-shape filter. At first I was happy with it, mostly due to some added engine noise, like hissssssing and especially turbine backflash, which became really noisy. And I like it sound like Godzilla, lol

But after few 1000 miles when I first washed it, I became sceptical. As I drive some off-road too, that became obvious on air filter. K&N was all over covered in dirt, actually some pieces of mud were there, too. I washed it, but by feeling I questioned about it being sufficient for such harsh filtering.

So for now I just washed it (no WD-40 spraying), put some 3-4 layers of kitchen A/C filter around it, until I reassemble OEM filter back. I guess in time damage to engine could be done due to less restrictive filtering with those "sport" filters.

[forgottenzone]

Personally from experience i would advise against the K&N oil filters. I use to use them untill inlearned better. 1st of all they are crap. Its like putting 1 layer of gaze and oiling it to protect your engine. You can find alot of this info and testing on the net. 2. It coats the MAF sensor with oil which gives wrong reading to the ECU. And eventually MAF will go bad. There are so many difference filters and CAI's now available with dry filters thar last long and can even be cleaned and reused that flow better air then k&n. Which is old technology that has been surpassed. I have been using Volant CAI with dry power core for some time now in my V8. You can find posts on it in here. Now I have upgraded to the best filters out there made by R2C company, they are dry filters that can flow 1,600 to 3,000 CFM's ,which is way more than any engine out there could need 5 times over. And best thing is to clean it you use compressed air and blow it inside out . And it lasts forever.