Drop in K&N filter worth it?

[Fudd]

I have a drop in K&N in mine, noticed no power gain whatsoever. I didn't buy it thinking I would get any, just had a 20 dollar Summit gift certificate to spend. I mainly got it for the lifetime usage. I have an 89 4.0 .040 over w/ mustang injectors and a borla catback FWIW

 

[viperbaron]

I put a K&N oil soaked high flow air filter in my F-150. Only made the intake noise louder at full throttle. Was not cost effective.
I cut aux air holes in the lower part of the stock airfilter box of my XJ to facilitate improved airflow with a stock paper filter.

 

[bjoehandley]

I did new cap and rotor, a drop in K&N, Bosch Single Platinums, and MMP 7.5mm wires last september and noticed a slight bump in power over stock plugs, wires, cap and rotor, and what ever airfilter Carmax had stuck in the truck. Dad and I also noticed a bit of suction noise from the intake through an unmodified airbox.

 

[jeep1947]

With just a K&N alone the gains will not be that great. however if you have say an exaust system and bigger tb the gains will be more. The more you modify the more gains you will be seeing from the filter. The amount of power made by a motor is determined by the amount of air/fuel you can cram into a motor and how fast it happens. A K&N will alow more air to enter the motor faster, but unles you have exaust mods the air will not be able to get out faster. I personaly think its worth it. And for the saving the motor from water part, yes a k&n will save the motor. Paper absorbs water and oil resists ever think about that?

 

[Cjmartz2k]

Splashing, maybe. Not sucking water in. Also, I don't know about the rest of you but my factory replacement paper filter had foam attatched to the bottom of it; I guess to repel water. If you are cruising through water hoping the "k&n will save the motor", I hope you have another ride home :lecture:

 

[XplodJeepster]

I will always remember the ping pong ball test for a k&n filter.

a cabelas store I went to had a little fan motor in a plexiglass case with a slot for a filter and a tube with measure marks on it.

( the fan probably had the the equivalent power as one of the stock air tubes)

anyways, they had a fram, then a k&n.

no filter - ball shot to the top. (duh)

fram filter - ball hovered about a 4th the way up the tube.

k&n - ball rose about 3/4 the way up.

I dunno about you guys...but i trust the ping pong ball.

and no, it wasn't some salesdude showing off k&n's, i placed the filters in and out, no cheesy sales gimmicks here.

 

[lost1]

I put a drop in K&N filter in only a few months after I got my jeep. FOr a while I was pretty impressed by the different response, until I realized nothing had changed at the pump, and once I swapped it out with a paper filter I felt no DECREASE in response. In other words, it was all psychological. (sie- ko- lojjik -kul for those who don't know) I have no doubt it works well for other setups but the 4.0L XJ's system doesn't seem to care.

 

[teookie]

I noticed no difference other than sound when going to the K&N tube filter. I noticed a small performance increase after putting on my exhaust.

 

[Beej]

I don't know about the drop in, but I have found a difference with the K&N homebrew fipk/cold intake I fabbed. There is a particular stretch of highway that I had a hard time passing slower vehicles on because its a continuous steep grade. The jeep would bog down at WOT, and now it pulls continuously. That alone made the change worth it for me...

 

[badron]

I fair test would be to pop in a CLEAN stock filter. Do some 1/8 1/4 miles test WITH a stop watch or go to a strip. Then pop on the K&N and do a few more runs. Look at ET and trap speed.
Besides the real bottleneck is the sharp turn the air takes going into the TB. A sidedraft intake manifold would have been nice (hint factory boys) or a GOOD hood scoop will do more for top end power. Then any oil rage air filter will (by itself).

 

[jeepbme]

I didnt read all the other messages, but i just wanted to say i love my drop in.

I paid 50 but i know it was worth it. You can feel a difference and overall driveability is improved. I prob got 4 hp maybe more, but i run a high flow exhaust in addition.

just my 2 cents

 

[red91]

I was thinking of putting in a drop in K&N filter on my 89 4.0 XJ. Right now I do not want to go the tube route. So do you think it is wort? Do those that have used it have any comments?
Thanks
BSD

Buy a K&N.

Wash your old fram filter.

Install K&N.

Wash it in 6 months.

Reinstall K&N.

Fianlly throw away the old fram filter becuase its a POS.

 

[j99xj]

The flat K&n is worth the money, but the fipk is a waste. The flat one should give you a few more horsepower. But one of the biggest things your can do to improve performance of any engine is make sure its getting cool air. Hot air will usually negate any flow gain.

 

[Beej]

The flat K&n is worth the money, but the fipk is a waste. The flat one should give you a few more horsepower. But one of the biggest things your can do to improve performance of any engine is make sure its getting cool air. Hot air will usually negate any flow gain.

I think you just contradicted yourself. I agree that purchasing the K&N fipk is a waste, but only because you can build it yourself with some PVC, ABS or aluminum tubing and a couple of CCV ends for about 10 bucks. Add in some heat shielding and you are good to go. Otherwise, the flat K&N does nothing to reduce intake air temperature...

 

[Dr. Dyno]

Dr. Dyno makes three strikes for a home run

The problem with the stock intake is that the front tube on the airbox is too small so that's where the main restriction lies, not in the air filter. If you go to http://www.jeep4.0performance.4mg.com/ramair.html you'll see what I did to my stock intake many years ago. Basically I did the following:

1. Enlarged front rectangular airbox tube by 50%.
2. Inserted a K&N 33-2018 drop-in filter (flows ~450cfm as opposed to ~370cfm from a clean stock filter).
3. Removed the "trumpet" that was restricting the airflow coming out of the airbox lid.
4. Insulated the airbox with my famous foiled windshield sunshade to lower the intake air temps. This trick really did work as I found out with my digital thermometer.

This is fine as long as you have a mildly modded bolt-ons 4.0. If you start getting into porting the head and/or adding a cam, or you have a stroker, you need something better-flowing. Enter the FIPK but not K&N's expensive kit that still breathes hot underhood air. I'm referring to my expertly designed homebrew FIPK instead. Crude but highly effective. Take a look:

http://www.jeep4.0performance.4mg.com/FIPK.html

DON'T use metal tubing for the airtube. It acts as a heat sink and raises the intake air temps. Use PVC plumbing pipe like I did instead. Oh, and you don't have to stop there. If you really want to lower intake air temps. and underhood temps., I have another trick up my sleeve. Stick an insulating blanket to the underside of the intake manifold. It really does work:

http://www.angelfire.com/my/fan/manifold.html

 

[ricot83]

Yesterday made me love my k&N, u know what else made me love it? I got it for free at a junk yard. Last night i went in a huge mudd pit, muddin the airbox and everything so i take the filter our and its covered in crapwashed it off re-oiling ikt today and all set.

 

[gradon]

On my 94XJ, I got a bored out 62mm TB, Borla header + catback, magnaflow cat, Jet stage 2 chip, so when I added K&N's FIPK it made a huge difference. I've since added an adjustable MAP sensor that I made (set to 6V). Last week I scored at the junkyard and got a 99 intake manifold for $25, so I'm anxious to see what 1700 cc additional, more efficient airflow will do.

 

[Big Red]

Get a cone K&N, the very fact that you have to drop the filter in the air restrictive stock box defeats much of the K&N's benefits. The K&N has a million mile warranty so that alone should justify the higher cost in getting one. Also it is easy to clean and reoil with the recharge kit. The Rusty's K&N cone conversion kit is a great deal at around $60-70 for the K&N cone and air tube. I definately notice a little difference when I go from the stock air box to the cone, also from the cone to the stock air box with a K&N drop in panel. I get a nice high pitched wisseling sound when I rev up the motor, suck in that air baby! :laugh3:

 

[j99xj]

I used to run Rusty's cone filter kit.

I took it off and replaced it with the stock air box with a flat K&N. I bought a 3'' diameter tube, hooked it up to the larger holes I made in the airbox and sheet metal, insulated the airbox and tubes and I now have a true cold air intake.

And honestly it has more low end power than the cone K&N, but slightly less top rpm horsepower (4500+). This is because it has cooler air to breathe.

Some of you might ask why I didn't insulate the cone filter to have the best possible intake. The answer is that I did. But all my attempts ended up looking like crap. It is difficult to make such a shield when there is no structure around the air filter to use.

I'm very happy with the modded stock air box and K&N. It may not be the best for a stroker or high revving 4.0, but it does just fine on my 4.0 that loafs along at about 2000 rpms most of the time.

 

[jeepbme]

i went with the flat filter in the stock box...ive been known to do some muddin here in NC so i want all the protection of the plastic compartment to shield any water or mud that might come in the engine compartment.

I LOVE MINE