what do you think of K&N air filters?

[aboyandhisdog]

I broke down and ordered a K&N air filter today, as I am wanting to get as much airflow as possible in my old Ranger.  Any thoughts as to whether or not these really do allow more air in, help with power, mpg, etc?   

It got me thinking about the Donaldson filters on our Willys which seemingly don't inhibit air flow at all.  But do they filter the air all that well?

[zooke581]

I put one in my 92 F150 years ago and had to go back to stock.  I really messed up the driveability.  On my motorcycles they were okay as I rejetted them anyway.

[macrisel]

I have had several vehicles over the years with K&N filters and you should take most of their claims with a grain a salt.  On a bare bone stock vehicle, you are probably not going to see much, if any, difference in HP, torque or MPG.  However, if you combine the filter with other mods (such as a cold air intake, better exhaust, cam swap, turbo, etc...) you'll notice a much bigger difference.  The one thing you MUST do if you do any of this is take the vehicle and get a custom tune put on it.  Don't bother with buying a boxed plug-in tuner as they only change a few setting on the ECMs.  A skilled person with the right program can change three times as many settings and customize the tune to your driving style and how you use your vehicle.  The cost is usually cheaper also.  As a bonus, if you make any other mods to the vehicle, they will usually reprogram it for free.  The last three vehicles I've had tuned cost between $200-$300 per vehicle and ran and drove MUCH better than a stock tune.  Two out three got 2-3 MPG better after the tune.......(the third vehicle was a 2wd truck I had souped up to blow money on and get into trouble with..

The only reason to switch to a K&N on a stock vehicle is to same money replacing air filters in the future.  I live down 4 miles of dusty gravel roads and usually change my air filters every 10,000 miles.  The paper filters average $8-14 per filter and a K&N is usually around $40-60 per vehicle.  After 50,000 miles you have your money back.  BTW, there is NO way I would go 50,000 miles on a K&N filter (as they claim) between cleanings.  I usually go some where between 15-20k on mine.

Good luck!

[aboyandhisdog]

Excellent advice, Mark, thanks.  You've got me thinking though that there is more I should be doing to get the most from my truck.  But will probably just stick with a good air filter for now.  Money would unfortunately probably be better spent towards a different truck rather than modifying this one...unless I could be sure of what I was going to achieve.  Hate to roll the dice for only a moderate return in performance.

[aboyandhisdog]

Drove out to my local "test track" last night - a long pull up a very steep hill to see if I could see any benefit to the K&N.� First drove up it as fast as I could without an air filter, then tried again with the K&N.� I didn't notice any difference at all, which is what I wanted to know.� As far as I can tell, the K&N lets as much air in as no filter at all.� May try this experiment with my old paper filter too, but no time last night.� Hated to spend $50, but at least it will be the last $ I spend on an air filter.

[johnrb3b]

Just as a general, philosophical statement:
If just swapping out an air cleaner would gain horsepower or mileage or whatever, Detroit would be all over it as they go to sometimes ridiculous lengths to gain a fraction of a mile per gallon for the Federal EPA requirements.

Things like throttle body spacers, low restriction exhausts, etc. never give you what the sellers claim. If they worked that well, that easily and cheaply, they'd be on all the manufacturers' cars since they have to work pretty hard to get their CAFE (Corporate Average Fuel Economy) rating up to Fed requirements.

As macrisel's post showed, any significant increase in power or fuel mileage requires a complicated, interrelated combination of components and tuning. They all work together as a system. Changing just one component isn't a magic solution.

Reusable filters like the K&N can save money over the long run if you drive enough miles under dirty conditions. But for the average guy, it's mostly just hype.

[johnrb3b]

In the same vane, here's a story from my Iowa farm days.
Back in the '60s STP was really marketing to farmers, claiming they could get big horsepower gains in their tractors by adding STP to the oil sump.
The salesman came to us because we were one of the larger operations in the area. We had five tractors and a combine. He thought if he could sell us, the rest of the guys in the area would follow.

So we took the W450 to town and put it on a PTO dynamometer. While the engine was running under load, we added the STP. WOW, horsepower went up a lot. I don't remember how much but it was significant. We were all impressed.

We then went home and spent a whole day plowing - pulling a plow with four 18" bottoms in peat soil. Hard work.
Next day we went back to the dynamometer. Guess what. It was back to the original HP rating before the STP. I guess the "STP effect" lasted a few hours under load.
We told the sales guy "no thanks".

There really are no magic bullets.

[F Bill]

In the escort business we really rack up the miles, and extended oil change intervals and filter intervals really add up your savings...problem is we do a lot of traveling behind a 13 axle trailer rig and it kicks up a ton of dust, especially on the jobsite roads...One of my buds put in a K and N and pulled it out soon after, as it stuck to the dust so well it clogged up way quickly....Of course it was removing the dirt from the intake air which was good, but the pleated paper filters tend to drop the bigger particles to the bottom of the air box instead of sticking to them...I won't use one in dusty conditions.....the stock 3a oil bath filter is pretty good, and there are paper filter conversions I haven't tried yet.

Not quite snake oil but pretty close in their claims...much of the improvement on their filters for newer trucks comes from an improved and more performance oriented air plenum/intake duct. Which may very well be great for a truck driven on pavement only but some of them might tend to suck up water more than the stock filter..

[Gunslinger]

K&N had a book up at NAPA that I went through for my vehicles, and yes I am biased against their claims..  but they advertised a 10 hp gain just by putting on their filter.  When you looked at the data they published they did actually get that performance improvement, but it was all at 6000 rpm or higher.  Now I don't know about you guys, but my Silverado never sees 6000 rpm, neither does the Cherokee, so I passed. 

As Mac indicated, you can do so much more with a good tune job, and the oe air filter systems are extremely hard to beat.  You really need to up the air flow on an engine to be at a point that you need to reduce the restriction on the air filter. 

One thing I can tell you about filter life on OE filters is that 90% of us throw away good filters at the change interval.  Chevy started putting a device called a Restriction Indicator on the inlet of the air system.  Its a little plastic gage that never seems to move.  I watch it continuously on mine and I try to teach my customers to use it.  It really does tell you when to change your air filter.  I normally run about 60,000 miles on an air filter on my Silverado because that is when the indicator tells me the filter is plugged. 

One of my customers went from a 250 hour change interval on his 400 ton haul trucks to 1000 hours and he wants to move to 1500 hours as he knows he has more filter left.  All because of the indicator.
Just sayin....

[aboyandhisdog]

I've always kind of held the view that about any mass produced product can be improved upon.  But it sounds like I may have just spent about $40 more than I needed to by buying into the K&N claims.  Sounds like keeping it clean is key, and at least when I'm screaming up the pass at about 20mph pulling my 3A, at least I'll have the peace of mind that about as much air is getting to the intake as I can reasonably afford.  Thanks for the input!

[Lee]

MHO,  several years back our Mobil oil rep purchased a new Dodge pickup. It was used as a test truck for mobil 1 products, I believe it was an 01-02 model year. Mobil did oil samples every few thousand miles as the engine oil was being tested to 16,000 miles change intervals. So everything was very closely watched on this truck. At one point they installed the K&N setup, after the following oil sample came back it was cleaned lubed and re installed as the sample was extremely hi on silica (dirt), next sample was worse so the stock filter setup was re installed, the next sample came back as normal with the stock filter. His advise was to not use the K&N on a daily driver or anything else. 

Lee