K&N filters - icky

[Anthropy]

First, I want to say hi to every one. I have not visited the NAXJA's website for an awfully long time and it is nice to see you have found a nice home. The last time I was around was when we had the ghost on the main page that would not go away.

So, to my subject of K&N filters being icky. This weeked, I removed my cone filter to check it out, see how dirty it was and all. It had been a year since I installed it along with my vacuum gauge to measure head loss (dirty filter gauge). Well, I was pretty shocked to find a layer of find grit on the inside of my home made air tube adaptor and the vacuum gauge had not moved - no head loss.

I wipped out the inside of the air tube and then re-installed the filter and drove for the week, then rechecked it today. Guess what, there was grit on the inside of my adaptor again.

And the past few days I have driven to and from work 5 times and it takes me about 5 minutes to get there, driving on paved roads.

So, to all of you out there who think that you are safe, you are not. Go out and get one of the foam pre-filters before it it to late. I am off to the auto parts store tomorrow morning in search of one. Otherwise, I am putting back in my stock paper filter until I find a better solution.

XJGuy is correct, the K&N's do not protect. Now I have to live with the idea of all that crap that went right into my engine the past year. ;(


Tom R. Dennis

[TOZOVR]

I've been saying this for years. IMHO, K&N's suck for filtering efficiency...look around the web for some of the diesel tests.

I like Wix:D

[Kejtar]

hmmmmm I don;t know about that...... I put in my K&N a while a go (the bigger cone went in over a year ago) and I have pulled it twice (once to redo the mountm once to clean the TB) and it looked all good inside: no extra crap, no sand, no discoloration and so on...... I guess it all is also related to how well it;s loaded, cleaned and so on: I heard of someone using a harden hose to clean his whci is a nono as that just kils it.

Kejtar

[TOZOVR]

Filter better or flow more. Choose one.:D

[Kejtar]

Ther eis a happy medium out there someplace.... :D

Kejtar

[Anthropy]

I could not see the fine grit. I took my finger and ran it inside of the tube to see if Icould feel anything - yes, I could. But, no it was not visible to the eye. This stuff was very fine, but was abrasive feeling.

My air tube is a 3 inch stainless steel exhaust adaptor that is about 6 inches long. I drilled and soldered the crank vent nipple to it along with a small nipple for the rubber tubing that goes over to my head loss gauge.

No leaks around the nipples - I used high temp silver solder so the joint is strong.

Bad thing about the whole thing was that I had just freshly spray oiled the filter using the K&N oil after my primary inspection. No wonder the synthetic oil always looked dirty when I went to change it.

Tom

[TOZOVR]

;) It's still beyond me why you folks would want to suck hot engine bay air anyhow...and "more" of it at that! ;)

[Handlebars]

Cheap help for K&N cones- a shop vac filter bag.
http://www.fototime.com/69764CEB975522B/standard.jpg

I've been running it that way for the past 45,000 miles. 140k on the Jeep now and it doesn't burn oil. :)

[C-MuRdaA]

Originally posted by TOZOVR
;) It's still beyond me why you folks would want to suck hot engine bay air anyhow...and "more" of it at that! ;)


http://community.webshots.com/album/33598274mjXQcW

[TOZOVR]

Alex and Chris both pose viable solutions to issues...but why not just run a box? :)

I'm just playing Devils advocate here...filter/box setups are a personal pref....much like chevy vs ford etc....


RJ

[Kejtar]

Well there is more then one benefit to the cone...... in the older XJ's the box seemed to have a matching hole in the front grille (matching to the intake that is) while the newer XJ's don't seem to have that: that I think ends up limiting significantly the amount of air coming in...... Also with the cone you end up gaining extra room: I'm looking into sticking the wiper fluid container there as I need it to remove it from the fender.....
Also for extra cleaning.... you can always put on a prefilter of sorts..... they make them for the K&N's
Kejtar

[MudDawg]

I deal with air filtration on a daily basis...there is a distinct difference between "high performance" and "high efficiency"..a "wetted gause" filter does well to keep alligators and logs out of your engine...at least run a foam prefilter..I'm sticking with pleated paper...and if i ran in a dusty environment, I would run a prefilter on the pleated paper element...the head loss gage is a great idea ...:clap:

[Anthropy]

If you are interested in the loss of head gauges, do a search for: air filter restriction gauges

Here is a page I found - it is a pdf format.

http://www.fleetguard.com/fleet/pdfs/product_lit/south_pacific_news/3300920A.pdf


The first time I saw one used was on one of our F-250 service trucks. The one I purchased was scaled to 18 inches of vacuum.
---
I tried to find the foam pre-filters for my K&N, but none of the ones I looked at would fit. I mine is 5" at the base and 4 5/8" at the top and is 8 inches long.

When I went to choose a cone style filter, I made up a little spread sheet to give me the various surface areas of different diameters and lengths. You entered the bottom diameter, top diameter, and length. It would calculate the area. I still have it if anyone is interested - it is in a ms office xls format.


Tom

[2xtreme]

I just switched from a flat K&N filter in the box to a large K&N filter and I definetly notice the difference in power above 2K rpm. I noticed no difference switching from paper to K&N in the box. I sitll have to build a heat/mud shield but that will be done soon.

I have used K&N filters on at least 3 different vehicles over the last 15 years and I have never run into any issues that you have discussed? I have had them on off-road and on road vehicles and I have used them in Az (very dusty), CA and WA and they have all worked really well for me. I have also used prefilters on some of the applications but not all of them.

I do like the vac bag idea, very nice!!

Tom, your K&N part number is RE-0910, the filtercharger for you filter is Part number 25-0810. the precharger for your filter is part number RE-0910PK, but it says it is only 7" long?? not shure why??

Michael

[XJguy]

A clean paper element filter will flow as much as a clean K&N, and filter much better. K&Ns only have an advantage when comparing a dirty paper filter to a dirty K&N. The K&N has holes so large that even loaded with filth it still flows well, but at the cost of your engine's life. Someone do an oil analysis to once and for all put this to rest.

I have read several real world independent dyno tests using "high performance" air filters, none showed an advantage over a clean paper element, certainly nothing filters better. Want more flow, dont think paper gives you enough? Easy solution, get rid of the air box use a humongous conical paper filter and you will have enough surface area to filter air for a Boeing 747...its what I did in the 89 I used to own.

XJguy

[TOZOVR]

Originally posted by XJguy
A clean paper element filter will flow as much as a clean K&N, and filter much better. K&Ns only have an advantage when comparing a dirty paper filter to a dirty K&N. The K&N has holes so large that even loaded with filth it still flows well, but at the cost of your engine's life. Someone do an oil analysis to once and for all put this to rest.

I have read several real world independent dyno tests using "high performance" air filters, none showed an advantage over a clean paper element, certainly nothing filters better. Want more flow, dont think paper gives you enough? Easy solution, get rid of the air box use a humongous conical paper filter and you will have enough surface area to filter air for a Boeing 747...its what I did in the 89 I used to own.

XJguy

Well said!

[Karlm]

If you are interested in prefilters for your K&N or other open element style filter, check out a company called Outerwears. They make prefilters for K&N, but if you call the company direct, they will make any kind of pre-filter you want. Pretty much they'll make anything you want out of their filter material. They even have a specially treated material that repels water but lets air through (This is what I have on my filter. It works OK, but if you submarine the filter, I doubt it would do much good.)

[RichP]

While you guys were posting this earlier I was doing an oil change on my 98 so while I was waiting for the drips to stop I popped my air box. Checked the air tube and ran an old clean bathroom towel thru the tube. How the heck did all that crud get in there. Yea, I run the K&N flat panel and changed it a few days ago but it has not been in there for a few months since the last time I swapped it out to clean and oil it. I have a OEM paper in there and will be keeping an eye on it. Next sat is plugs/wires/cap/rotor/coolant flush and new belt day and I will run another towel thru.
I think I might also duct tape the joint between air box and the air tube, I don't trust that squeeze fitting.

[Anthropy]

I took off the cone and put back on my old air box and paper filter until I get something better. I like XJGuys idea of the cone paper element and found the elements, but not the container. Anyone have any leads for round filter holder assemblies that have a 3 inch attachment for the duct?

If not, it will be fab time. Use some stainless flat plate with a hole cut out in the middle for the pipe and then run a stud up through the middle and then a large washer over the stud with a wing nut.

I liked the K&N because I could attach it with a hose clamp. I am just not sure that even a foam prefilter is the way to go. However, a foam pre w/o oil over a paper might just be the ticket.

I think the way to go is the corse filter over the fine. The course one catches the bugs and stuff, leaving the paper for the fine particulates.

Tom

[RichP]

My wifes 96 Olds Cutlass has a round can filter element, been a while so I don't remember the size, I'll grab a flashlight and go look....yuppers, looks the same size, maybe a hair bigger.

[Jeremyvnc]

I'm Still looking for a scoop hood for my xj anyone have any ideas on where i could find one?

[Moto]

Alex and Chris both pose viable solutions to issues...but why not just run a box?

Tozovr You have a snorkle on your Jeep, are you still running the stock airbox? I thought the only solution to the low hanging snorkle tube was to install the cold air intake tube thing???

[TOZOVR]

I run Pizza cutters (32x9.5 TSL bias plys) and no Bumpstops and have yet to hit the snorkel tube (I do have the stock box). Once the CRSU long arms I will check the placement and see if the tires are coming close (with the RE arms at 6" of lift the tire sits farther back in the wheelwell so it's actually farther from the hose...if the arc of travel is moved further forward it may become an issue. I'll change the setup if it's an issue, I won't run a cold air canister.

[andyr354]

K&N = short engine life in my opinion
K&N is all marketing, somebody should do a placebo test on somebody where they claim to put one in and I bet they would say it ran better.

I run an amsoil foam filter just because it stops more than a paper filter can with better flow.

I know some guys that were running K&N filters on their 750cc Kawasaki dirt track engine. When the filters were oiled to stop the dirt they made the engine to rich since they were choking off the air. So he ran them dry (dumb), dirt killed the engine halfway through the season. He now runs oiled foam elements.

[Ed A. Stevens]

We all have opinions, I respect other's opinions, and this is my experience directly related to my XJ (FWIW).

K&N flat filter on my 88 4.0L, installed at ~30,000 miles (1989). The filter was washed and reoiled with a K&N filter charger kit about once a year (~20K-30K miles). Travels included weeks in Baja, severe dusty conditions, and extended service in the desert & mountains (my fathers ranch is all dirt road access).

This is what I found when I tore the engine down at 200,000 miles (1997):

Cylinder taper = ~0.002", no sharp ring ridge.
Valve guide wear = none to worry about.
Crank journal wear = rod journal clearances at ~0.0025" on the thrust diameter, and ~0.0020" on the perpendicular radius (oval journals, but within spec). The main journals were the same but ~0.0030" and ~0.0025".

The block was bored 0.030, the crank cut 0.010/0.010, and the stock valves reinstalled in knurled factory guides.

The engine would pass CA emissions tests with, or without, a cayalytic converter (I ran an empty converter in Mexico due to the poor availablity of unleaded fuel). The K&N made no emissions impact if clean (borderline emissions failure w/o cat when dirty). I experienced no negative emissions impact from the K&N oil.

The rebuilt engine now has 40,000 more miles, with a new K&N (the old filter is in the wife's 89), and burns no oil.

This wear is very reasonable for an engine under clean air street use conditions and 200,000 miles. I consider the wear very light wear for the extended 4Lo OD WFO-slogs in Baja sandwashes, Nevada dry lakes, and high desert & mountain ranch roads that I drove. I would sometimes find the airbox bolt heads buried in silt, but little downstream of the filter (other than the oil blowby that every hi-mileage 4.0L suffers).

I agree, a new paper element flows nearly as well as a new K&N, in an XJ application. The performance advantage is slight (2% at best). The airflow at 15000 miles is quite different, where the K&N has an advantage (IMO).

Does the K&N offer poor filtering? It filters less effectively (compared to a new paper element) when clean, but quickly matches the paper filter performance as it loads up.

Is the duration of time where the clean K&N is less effective a risk?

I don't know, from instrumented testing, but my experience is a 500 mile road trip after a filter cleaning is enough to provide adequate filtration efficiency from a K&N in severe conditions. This is what I would typically drive after cleaning the filter in preparation for a Baja pre-run, an LA area to San Felipe road trip before spending a week slogging the roads and washes between Ensenada and San Felipe (three times year minimum, from 88 to 96). If the filter failed to protect the engine when clean, I would have expected much more wear than what I found.

I have experienced no abnormal engine wear or emissions impact that would make me fearful of running a K&N (why I continue to run them, as opposed to changing a paper filter every 10,000 miles).

Anyone have experience to share that is similar, or different, from this (post K&N engine teardown analysis)?

[CRASH]

I'll soon have my own engine tear-down analysis, after running a K&N for 112,000 miles (half on a flat panel, half on a cone).......stay tuned.

CRASH

[BrettM]

while we are on the topic of K&Ns I have a question:

A K&N that has been wind-blown and turned white, is there still oil there? Is it still filtering as good as the redish part?

I recently put a K&N oval filter mounted just behind my throttle-body slanting backwards. I cut the hood to give it room and it sticks out about 1/2 or 3/4 of an inch. I've driven it probably 200 miles and just that part sticking out of the hood has turned white. I'm gonna get a little scoop, probably put it on backwards cowl-induction style, but in the meantime is that white area not filtering properly?

[Ed A. Stevens]

Originally posted by mad maXJ

A K&N that has been wind-blown and turned white, is there still oil there? Is it still filtering as good as the redish part?



I do not know about "as good" but a K&N rep told me that as long as it is collecting grime it is working as a filter regardless of the color in the fabric (this was for a VW buggy application that sat outside between trips).

To be safe, it makes sense to clean and recharge the filter to keep some oil in the element. A quick spray from the recharge oil bottle should go a long way to keeping the element wet. I would also consider an outer filtersock of some kind just to prevent sun bleach (what we ended up with on the buggy).

Crash, thanks for offering to post the tear-down inspection results.

[TOZOVR]

Not doubting the tear down analysis done by any, but to do it objectively you'd need the parts tested before and after for any kind of relavance.

[Tom Campbell]

Well i dont liek the idea of the K&N's on the trail so a paper switch was fine. but now im kinda stuck. In my quest for a snorkle, i bought a cold air canister. Does anyone know of a better filtering elemnt that i could use for my cotton cone filter? Its the 5" from intense performance. a prefilter would be ok . just something better. i found crapin my intake and even had some sludge in the intake manifold by the ports when getting a header done. I dont know if this is because i soake dthe k&N or if its becaus ethe box didnt seal as well (it didnt) or because the K&N wasnt big enough. (I found gaps at the corners. :rolleyes: So i would like the ability to swap theK&N lookalike for something better or at least get some prefiltering for it.
Help?

[Moto]

I used to run a stock replacement K&N but it got too costly to constantly clean it and the performance that I noticed was minimal, doesnt seem worth buying one for almost $40 then the recharger kits which start at arount 15 when you can go buy a new paper element for about 5 dollars which works out to be what 11 or so paper filters for the price of one K&N

[Tom Campbell]

Originally posted by Kejtar
Also with the cone you end up gaining extra room: I'm looking into sticking the wiper fluid container there as I need it to remove it from the fender.....
Kejtar

FYI I am doing the same and i found that a bottle from a hard top tj will work perfectly for this and look factory. i got mine off a 99. Of course i have a 98 so if you have a 97 or newer this would make a good option.

[XJguy]

Do what I did, got to Pep Boys or your store of choice and rummage through all the filters. Youll find what youre looking for. The unit I settled on was about 10" long, 5" in diameter and had a 3" opening, someone told me it was for an Acura, I dont know, this thing was huge.

Here is a photo of the setup I had in the 89 including the oil blow by catch, you cant see the filter too well though.

http://members.aol.com/xjguy/images/dsc00002.jpg

Here how I did it:
Buy some 3" dia PVC pipe from Home Depot, also buy some brass fittings that will fit the two hoses connected to the air box. Some large hose clamps that will fit around the pipe. Also buy a 3" rubber union to connect your airfilter to the PVC pipe. Remove your airbox assembly. Cut the accordian portion off your OEM airtube. Cut the PVC pipe to desired length. Make holes in the PVC pipe to fit the brass fittings. Grind down one end of the PVC pipe so that it is beveled and will slide into the remaining portion of your stock tube. Clamp it. Stick the rubber union on the other end, clamp it and your filter on the end of that. Attatch the 2 vaccum hoses and you are ready to run. You can paint the PVC with some low gloss auto paint so that it will look factory. You can also make an enclosure out of some aluminum sheetmetal and some weather stripping isolating the filter form the hot engine heat..

What I plan to do next time is try and keep the factory airbox, and fit a conicla filter in it, and a NACA duct on the hood to suck fresh air into the airbox. I will cut off the restrictive accordian portion off the factory tube as I have in the past.

XJguy

[LT1XJ]

There are a lot of companies out there with filters that are better for filtering than the K&N. Amsoil, among others.