gcliburn

I was wondering what some other folks opinions of the k&n and similar air filters are. I currently have one, but was wondering how well others think they filter. Any thoughts?

loch

The only way to make a filter flow better is larger holes, K&N has these holes so its dependant on the oil charge to catch the dirt. However at 25 lbs of boost and up the oil has a very limited life as its pulled out. An easy test, any good paper filter, pull the air tube from turbo and wipe inside with a white cloth, if theres any dirt, your engines eating it. K&N will show a lot more dirt than even a stock wix filter.

lowwag64

I am running K&N now with stock box,I don't mind it.It does get alot dirtier running a turbo compared to my other gas veichles with K&N fliters.I probably will upgrade to BHAF in future and put the K&N on shelf.

1992 W250,4X4,STD,Pump tweaked,lil fuel,smoke,big inj.,gov.spring,gauges,dual batteries+fog lights on weekend.

flashgordon

My opinion with the k&n and like(oil charged filters) is the same as loch!!!!

if your going to drag race, tractor pull it exc........survive it, compete with it and put you stock or BHAF back in for the drive home! you won't find a higher flowing air filter! but there's way more efficient filter out here that flow almost as much air with only air getting thru!

Prove it to you self, put the k&n in and go play for a weekend and see how much oil is in you intake tube, drive it for several weeks and see how much dirt is stuck to the air charged oil in the intake tube.

a little oil mist in the intake side of the turbo......no problem.
a little dirt stuck to that oil and watch out!

I now I just lite a fire here but before you criticize me prove me wrong and the go a head and by the that k&n filter with proof!

Ace

Does this intake look dirty to you?

http://66.17.171.114/PhotoAlbum/Cars/Pics/CTD_43.jpg

It sits behind a K&N and I can assure you it passes the white glove test. K&Ns that got a bad rap were probably abused by people "cleaning" them with a compressed air hose, cleaning them properly too often, and/or not oiling them often enough for their particular enviroment. Used properly, they are great. They are just a little more complicated than popping a new one in every couple years.

loch

Ace your a sick man, anyone that keeps a cummins that clean just aint normal. Now run that cloth into the tube going to the box, and then clean it out and run a paper filter and compare.

Simple fact a K&N type filter has bigger holes, the filter is dependant on the dirt bouncing around and sticking to the oil surface. Now consider that a stock air box and filter are designed to provide around 500 hp of air, no real mod is even needed until we wrap the boost thru the roof.

Ace

It's actually pretty dirty right now, at least the bed is after hauling just shy of two tons of landscape rock in two trips last weekend.

So riddle me this: If the stock box/filter setup supports 500 hp, why is everyone punching holes in them, ripping them out to put cookware in there and other various mods, not to mention the little number I did on mine?

http://66.17.171.114/PhotoAlbum/Cars/Pics/CTD_54.jpg

Firstgenner

Good questions, I often wonder about these things myself. Is it the stock filter size that is restrictive or the inlet to the factory airbox that is the problem, if it is even a problem?

loch

Most ppl do it so they can hear the turbo, and it may help a tad, i didnt say it was of no benifit but that its not needed. But if you really think about it, you only need a 4 inch opening and it has more than that factory.

BearKiller

I will stick my two cents in here.

When I first got the Cummins in my truck, I had to stick a cone-shaped K&N, directly on the turbo-inlet, on account of clearance issues and a battery sitting right where the air-filter needed to be.

I ran this way for about six months.

I had reason to have the intake tube off the engine and it was pretty dusty and grungy inside.

When I first installed the engine, I had the intake tube off and cleaned it spotless, inside and out.

I don't know if the K&N was to blame, but there is a complete new intake system on there, now, with a paper element filter.

DJ

I tested my stock box with a manometer, stock at wot 25psi boost It had 9 inches water column resistance, I drilled 2 3 inch holes and the resistance dropped to 6 inches , that was with a filter that had 31000 miles on it. The factory says to replace the filter at 18 inches water column. Normal driving never goes over 3 inches so I don't think a bhaf or K&N could make a major difference except at wot full boost.

Ace

That was pretty much my take, without the actual measurement - way to go! Normal driving vs. full boogie. Who'da thunk it!

So, to summarize:

1) The stock box presents a measureable restriction, but only under heavy load.

2) The air filter prolly don't matter, but you might be getting dirt through a K&N.

rlyons

Because I love the sound of my ASA Modifieds.

Firstgenner

DJ,

Thanks for that info. It appears that by enlarging the factory airbox snorkel, you can gain a significant reduction in the restriction while still utilizing a factory-size paper filter element. I think that I will get out my can of ABS glue in the future and get to work on the factory airbox...

BC847

It's a bit rough from removal but this might be what you describe.



The duct opens just below the headlight bracket.