K&N for normal driving?

[Tempest]

I've got an 02' Liberty,3.7, 4X4, original owner w/original tires (Eagles) that I am trying to get better milage out of (with little succes). It is a city car that mostly transports my wife ~30 miles a day back and forth to work on pavement. Most of this (~%80) is good moving freeway. We always planned to use it for some light off roading but work and the birth of my son put a damper on that. So it has become a highway/city car.

I was thinking that getting more air into the engine (especialy since we live in a super heated dessert) would help things, but most all of the charts (like below) show output at the top of the scale/high RPM's.

@65MPH the engine sits around 2200RPM. The chart doesn't even go that low. I don't think the Jeep has ever seen 5K RPM...

So what do the members here think? Good for ordinary driving...or just for performance?

P.S. I would try to replace the K&N filter with an Amsoil Eao cone. The only one with the same Flange Inside Diameter is 3" longer though, so I'm not sure it would fit.

 

[surfstar]

I feel that the K&N (and most name brand) intake kits are WAY overpriced. I would check out ebay to find the correct piping from a knock-off kit and use a Eao or AEM Dryflow on whichever setup you get.

Depending on the stock setup, intake kits can make a noticeable or no difference.

You *might* see some difference at WOT in lower RPMs, but as the dyno shows, most gains from a high-flow filter/intake setup are at high RPMs only.

 

[ALS]

I know this is a air filter question but if you want better mileage here is what I would do.
I'm not a fan of K&N type filters but they and other aftermarket companies do make a cone filter setup for you vehicle. This set up eliminates the air box completely leaving you a pipe with a cone filter at the end.
Second I would fill the engine, transmission and differential with synthetic oils. Lastly I would increase the air pressure in the tires by 4 to 5 psi. That should be good for 3 to 5 mpg on the highway.

 

[mechtech]

K+Ns are a hit or miss option.
Don't over oil them.
Some people who drive in dusty areas have small particulate matter passing through them. The intake pipe downstream gets visibly dirty.
Others [like myself] have no problems in the areas that I drive in.
Power can go up by reason of less restriction, but that is generally dependant on if the stock one is undersized.
Some people do indeed have a gas mileage increase, but never a large one.

 

[jmacmaster]

"I'm not a fan of K&N type filters but they and other aftermarket companies do make a cone filter setup for your vehicle. This set up eliminates the air box completely leaving you a pipe with a cone filter at the end."

There's problems with this setup. You're talking about the so-called aftermarket performance kit, which as pointed out above, is way overpriced for what you get. On some applications, you get no, or minimal, hp and torque increase. You get little, if any, mpg increase. In addition, the cone filter sits unshielded in the engine compartment and the air it takes in is warm air, because of the heat from the engine block. Ideally, you want cool air taken in. That's why ideally an air intake box is located at the front of a vehicle to get cool air coming in from the grill and the air filter is positioned inside that box. Finally, with the cone sitting unshielded in the engine compartment, its subject to getting soaking wet by getting water splashed up on it. All in all in my opinion the problems with them outweigh any positive effects and they are a waste of a lot of money.

What you can do to make more air available to the engine and perhaps get a bit more hp and torque is modify the airbox. I would not do this unless the airbox is at the front of the vehicle and designed so that the filter sits at the top of the box. In this case, you can cut out part of the bottom of the front (verticle) panel of the air box, making an opening a lot larger than the stock opening in the airbox. You thus make a lot more air available to the engine and its still cool air coming in from the front grill and then up through the air filter. Sometimes this slightly increases hp and torque and sometimes it doesn't. Be aware that it will always result in more engine noise, but then a lot of people, especially young guys, like that added macho sound.

 

[SteveU]

I bought K&N filters for all our vehicles back in the pre bitog days. I never noticed any visible dirt behind the filters but didn't notice any performance or mileage gains either. I have since replaced the K&N's in the cars we're driving with Napa Golds, as soon as amsoil comes out with a universal filter the same size as the K&N in the bike that will be replaced also. I made it a point not to drive on gravel roads with the K&N's, the golds give more peace of mind for the odd time that I need to.

 

[ARB1977]

I just installed a AEM intake with the dryflow filter on my Tacoma since i wanted to try to gain alittle more gas milage plus with non oil filter.

 

[Blake Sobiloff]

I, too, am not a fan of K&N as they have proven to be very difficult for folks to install and maintain correctly. Most folks with K&N filters end up letting in a bunch of dirt through the intake, leading to worn valves and pistons, making engines drink oil far sooner than it otherwise would have.

ALS was right on the money with his suggestions: synthetic driveline fluids and a good eye on your tire pressures will save you more in gas than a K&N, plus your vehicle will be better protected (not more poorly protected like with a K&N).

 

[UncleS2]

2200 rpm at 65 mph? Then for commuting, I strongly doubt you'd see any gains in mpg or power. These things, if they add anything at all, usually only do it at the upper rpm range for a given engine. Unless, of course, you put a lot of faith in advertising.

Sounds a lot like my 94 Dakota 3.9 L V-6 ATx. Virtually everything it did was between 1500 & 2500 rpm. Highway mileage ran from 19 to 22 mpg- no matter what. (Except when I had the bug deflector on there for about a month- then it got 17.5 to 19 mpg!)

If I were in your shoes, I'd keep the tires aired up tight, use a 5w20(or a thin-side 5w30) oil, maybe synthetic, not run the air filter too long, & save the cost of that aftermarket intake system for gas. But that's just me.

 

[wiswind]

More horse power.....and more fuel economy.
Remember, in these non-carborator days.....with fuel injection and the oxygen sensors....working in closed loop.......the PCM is working to maintain a set air / fuel ratio.
So.....more air in = more fuel in.
Feels real nice when you press the gas pedal.....but addiction to the extra power = lower fuel economy.
The gas pedal is really a air pedal.....to which the PCM decides the amount of fuel to add to it.
So boosting the air intake beyond what the manufacturer designed would seem to have limited impact on fuel economy.

 

[mechtech]

There is a possibility that the engine wouldn't have to work as hard to ingest air with a freer flowing [K+N] air filter, thereby saving fuel.
At part throttle, most stock air filters are oversized and shouldn't be a restriction, though.

 

[bradcad]

i've had a bit of luck with the K&N filters both panel and pod. Little better econ, etc. Often i find plumbing up a custom air intake with smooth bends seems to help. I dont often experience better economy since I'm a hoon......

 

[Collie]

I had a Fram Air Hog Panel (a weak moment) in a 1998
5.0L Mountaineer.Fit was perfect. I know there are more
varibles, reasons, and E10 MN fuel and a dead skunk in
the road.......But it did yield and extra .2 to 1.3 MPG.HWY
But keeping your tires filled to max would help as much.
I can't believe all the tires one sees that are alarming low.
Synthetics in drive train can be a marginal help, but not
as far as marketing would have up to believe. I just use
them because of the climate extremes. But back to the
air filter/tube etc.if you don't mind the noise, go for it.
I'm still pondering a Brute Force system (dry filter).
for the Jeep Hemi.