Jeremyvnc
NAXJA Forum User
- Location
- Louisville, KY
I'm Still looking for a scoop hood for my xj anyone have any ideas on where i could find one?
K&N filters - icky
- Thread starter Anthropy
- Start date
Moto
NAXJA Member #576
- Location
- Right Field Bleachers
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???
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
NAXJA Forum User
- Location
- North Central KS
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.
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.
- Location
- Desert Beach So Cal
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)?
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
NAXJA Forum User
- Location
- Foresthill, CA
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
CRASH
BrettM
NAXJA Forum User
- Location
- michifornia
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?
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?
- Location
- Desert Beach So Cal
mad maXJ said:
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.
Tom Campbell
NAXJA Forum User
- Location
- Pittsburgh
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. 
So i would like the ability to swap theK&N lookalike for something better or at least get some prefiltering for it.
Help?
So i would like the ability to swap theK&N lookalike for something better or at least get some prefiltering for it. Help?
Moto
NAXJA Member #576
- Location
- Right Field Bleachers
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
NAXJA Forum User
- Location
- Pittsburgh
Kejtar said:
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.
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.
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
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.
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
- Location
- Pensacola, FL
There are a lot of companies out there with filters that are better for filtering than the K&N. Amsoil, among others.
