K&N air filter Yes or No?

[ColdFront]

Just wanted to see how many drivers are use K&N air filters or cold air intake systems in their xc70s? I have them on other vehicles I own. One for pure performance, another in my wife's daily driver which helped her pick up a couple mpg. Thought?

[Astro14]

No way.

Too many stories of over oiled K&N fouling the MAF.

Too many used oil analyses shows high silicon (sand) in the oil as K&N allows too much dirt.

[billr99]

I had a K&N on my 850R and ran it for well over 100K kms with no problems. Now did I get any real benefit? A bit more turbo noise (it had a 16T at max 14psi) and, maybe, a couple of extra HP; but overall it wasn't a huge upgrade from stock. I kept it clean and re-oiled according to directions and never had any MAF problems which many times result from people getting energetic with the filter oil. Interestingly, I had this when I lived in Northern Ontario which had a lot of road grit around because of the sandy soil as well as the use of grit during the winter. Again, no problems as a result and when I traded the car in at around 270K, it still was within spec in regard to compression.

I've used K&N off and on over the years on about a half dozen cars. This has included mostly small four cylinder motors, but I ran them on a couple of Land Rovers and the R. The only one where the filter produced a noticeable difference in performance was a VW Passat turbo-diesel; otherwise, a stock filter would have been just as good, keeping in mind the replacement interval. I'd advise that one save their money and stay stock in this case.

Cheers,

Bill

[Scopeman]

I agree with Astro 100%! My experience with oiled filters is the same, fouled MAF and high silicon (dirt) in the oil.

[Antherzoll]

A big nope.

My XC is modified, I use the stock air box and Volvo filter on my XC and it works well. From my observations the K&N filter vs the OE filter in the stock air cleaner, both flow the same but the K&N doesn't filter as well (fewer pleats = less surface area). I also have an 8" AEM dryflow cone filter, I do notice an increase in top end performance, but low to mid range are unchanged. This leads me to believe that the OE filter and box are designed well and have great flow, but the main restriction is the air box design not the filter.

Keep it OE, clean it out periodically, and change it more often if you're driving in dusty conditions.

[Iroll_]

Nope.
Mann, Mahle or OEM Volvo.
I prefer Mann as the're an OEM supplier to Volvo.

[Pennhaven]

I've been running a K&N drop-in in mine for about 14 years. Also used them on 5 other vehicles over the years. No related issues with any of them. Obviously it's important to not over-oil the filter after cleaning. Subjectively there is an increase in performance compared to stock, though it's varied by the vehicle - logically it depends upon how much of a flow "bottle-neck" the stock filter presents compared to the rest of the intake and exhaust systems. One thing for certain, as the K&N becomes dirty, usually after about 10,000 miles, I definitely have noticed a decline in performance under load, such as passing or hill climbing, with the performance obviously improving again after the filter is cleaned.

[StuntmanMike]

Nope. K&N just has a terrific marketing dept. Everyone thinks they need one. Unless you drive at WOT all the time you'll never notice any gain, and even then it's doubtful unless you're running a completely clogged filter.

If you want reuseable, get an Amsoil filter.

[Astro14]

That's just the point: "subjective" performance increases based on existing filter flow...and those results are...well...subjective.

I ran a K&N on my 4 Runner for about 12 years. When I replaced it with a regular filter (Toyota OEM) there was only a difference in intake noise...no change in power or mileage. It was a lot quieter with an $8 filter than it was with a $50 filter. And every 12,000 miles, I just replaced it, instead of fussing with cleaning and oiling. Look, if K&N really made all that much more power, and really flowed better, then don't you think that the manufacturers would use them on the really high performance cars? The Genuine Mercedes air filters (two, one just before each turbo) on my V-12 are, in fact, made by Mann. Plain old paper. Capable of flowing enough air to make 540 BHP. And when you add a tune, and bump the engine up to over 600 BHP? Yep, the tuners recommend that you use paper filters. AMG builds a version of my engine that makes over 600 BHP from the factory. It's a $50,000 option on the car. With that budget, they could use any filter they want...

So, they go with Mann paper filters.

Lots of folks confuse the increased noise of a cold air intake with increased throttle response or horsepower. But most of those intakes are only good for increasing intake noise...and, of course, separating people from their money.

The OEM filter on this car, and the good aftermarket filters like Mann, or Mahle, flow more air than the car can handle. They seal well, flow well, and filter well. For about $17.

There are lots of folks who have changed over to K&N, then an analysis of their oil shows increased silicon (sand...which means dirt is getting past the filter). I've done several oil analyses for the Mercedes and for both Volvos. The OE (Mann, or Mahle) filters seal well and filter well. There is no silicon in the oil. Silicon in your oil is a serious matter. It means that sand is getting into your cylinders in enough quantity to be dissolved in the oil. That means excess wear in the cylinders, and likely in the valves, turbo, etc. That's why the labs check for silicon.

You can spend a lot more, like $60 on a K&N, but you're not really getting any more performance. If you're looking for improved performance, replace the filter with a new OE style paper filter, spend the money you saved on new spark plugs, and make certain your wastegate is in adjustment. You'll get a noticeable, objective, measurable performance increase from doing those things.

[Pennhaven]

I said "subjective", to be sure, because without back-to-back dyno tests I can't prove there is an increase in performance. However, I stick by my assertion, even while admitting it is possible I may be incorrect, that I have noticed increased throttle response and passing power with the K&Ns on most of the vehicles I have had them on. (Not just louder intake noise, thank you.) If you Google around for dyno test results you'll find some examples of where the K&N drop-in helped (http://www.lsxtv.com/tech-stories/engine/dyno-test-4-kn-vs-aem-5th-gen-camaro-intake-options/) and some where it didn't. Which gets back to my point that it should depend on whether the greatest flow restriction in the specific application is in the factory air filter element or elsewhere in the intake and exhaust systems.

Actually the 2000 Mustang SVT Cobra R did come from the factory with a K&N air filter. The Cobra R was the then ultra high performance limited production "R"acing version of the Mustang, with 400HP, which was a big deal back 2000. I had the great pleasure of driving a pre-production Cobra R prototype in 1999 - but that is an off-topic story. To the point, the K&N was selected by the Ford Special Vehicle Team engineers for this original equipment application. Just one example, that I happen to be aware, I don't know whether or not there are others.

While it wouldn't surprise me that the K&N element would let more particles into the engine, and that this would be reflected in the oil analysis, without a very careful controlled (objective) experiment with two vehicles driven in the exactly the same conditions, one with the factory element and one with the K&N, and then performing an oil analysis on each, or else a large sampling of vehicles driven with and without K&N filters, I'm not sure whether it can be scientifically stated that the K&N is the proven cause of the higher silicate contamination of the oil; and even if it were, how much objectively proven increase in engine wear there might be.

Regardless, I'll still accept that the K&N might allow more particles into the intake engine, and if anyone's primary concern is engine longevity they'd be safer with the factory element. In my own case, I don't put high miles on my vehicles, even this now 12 year-old XC70 has less than 80K miles on it, and I change the oil and filter regularly, so I'm not particularly ;) concerned about a bit more silicon in the oil.

Also: Thanks for the performance tips, it lieu of a K&N. FWIW my waste gate was adjusted long ago, and I run copper plugs, which I change every 20,000 miles, because they also provide better ("subjective") performance than the more expensive factory iridium plugs. :)

[Antherzoll]

Dyno tests are not required, you can compare flow using MAF signal. I had logs on my old laptop and I'd gladly recreate them if I didn't ditch my K&N already. When comparing a new Volvo filter to a new K&N my logs had shown no difference in the same ambient conditions. Keep in mind that my engine is drawing 240-250g/s at max load, or potentially 292-304bhp which is quite a bit more than what the stock air cleaner is designed for, if there are any gains to be had with the K&N they should have been noticable on my logs.

Logging MAF signal is easy if you have the right diagnostic tool. Using an OBDLinks LX and torque pro I'm able to record live data to a .csv file. You can try it for yourself, I'd be interested in your findings. :)

[Pennhaven]

Dyno tests are not required, you can compare flow using MAF signal. I had logs on my old laptop and I'd gladly recreate them if I didn't ditch my K&N already. When comparing a new Volvo filter to a new K&N my logs had shown no difference in the same ambient conditions. Keep in mind that my engine is drawing 240-250g/s at max load, or potentially 292-304bhp which is quite a bit more than what the stock air cleaner is designed for, if there are any gains to be had with the K&N they should have been noticable on my logs.

Logging MAF signal is easy if you have the right diagnostic tool. Using an OBDLinks LX and torque pro I'm able to record live data to a .csv file. You can try it for yourself, I'd be interested in your findings. :)

No thanks. I'll take your word for it. If you're not logging any better flow with a new K&N versus a new paper filter with your mods, then it certainly shouldn't draw any more with a stock intake/turbo/exhaust. So that would leave the only argument in favor of the K&N (on this vehicle) that it might not clog up as quickly as a paper media filter, plus of course the re-usability aspect. In any event, I will stand down in this case. Peace. :)

(The reason I butted in the first place is that I'm bothered by all-or-nothing claims about things, without actual data for the specific case. i.e., a K&N can never help performance, when in some cases it actually can. But in the case of this vehicle I'll admit to being victim of my own confirmation bias.)

[Reverend]

That's just the point: "subjective" performance increases based on existing filter flow...and those results are...well...subjective.

Indeed. I have yet to see anyone measure the pressure drop through the filter and dyno the car before and after.

The stock airbox and filter is good for a good bit more power than the engine produces in stock form so there's absolutely no need to spend all that money on a K&N. If you want bang for the buck, get the car chipped.


EDIT: damn, Antherzoll said the same thing before me. THat'll teach me to skim the posts.