jplumlee

K&N is what I meant to write... Yes, I'm an idiot. N

I was able to find some older(er) threads on this subject, but not much.

So..... are they all they're cracked up to be? In their continued quest for increased air flow, do they really allow too much gunk through? Is there really any performance gain to be had on a normally aspirated Cayenne V8?

thanks, inquiring minds want to know!

HD2pct

I vote NO on B&N.

K&N is another story, however, and it seems like a mixed bag. Some people have "imagined" that it helped but I have never seen hard data on that particular engine from K&N or anyone on here.

Bob Rouleau

The paper air filter in you cayenne can flow 8 times more air than the engine can use. Flowing more air with the same surface area just lets in more dirt.

Your engine is a pump it can use 4.8 liters x the RPM and no more. While a K and N will flow more air the engine can't use more air than the regular filter provides. Do you think PAG engineers would leave (name your ficticious claim) HP on the table for the price of a filter?

pdxjim

I am with Bob!!

medtech

I use BMC. It does make it sound better. As far as performance, who knows.

As has been said before, if you go with K&N they should be "lightly" oiled only. New ones should be wrapped in paper towels and then blown out with an air gun before installation.

CDH-CTT

STOCK!!!!! I have done the "aftermarket air filter thing" Wiped out BOTH my MASS meters...after i replaced them i put my stock air boxes and filters back in...

ydlee

Just installed k&n drop in filters, don't know if it is a placebo or due to fact the filters are new and my old paper filters are dirty but I think I feel a slight increase in throttle response when gassing it. I never had any problems with oil build up problems from k&n filters from any of my previous cars.

grohgreg

Can't claim any performance, economy, or audible gains from mine. It's been in since new (<9000 miles). It's the extra filtration by the oil film that I'm counting on. Must have done mine right, cuz the MAF sensor is still clean

//greg//

ltc

If you use a K&N (oiled) filter and get a CEL due to a fouled MAF, do not come here asking for help.....or else....

HabitualViolator

i've logged more than 100K miles with K&N filters; Lexus GS300, Subie Outback, HD XR1200 and Mitsu Evo. No MAFS failures, no fouled plugs, no issues. Mileage improved by about 2 MPG overall for each. throttle/engine response also improved and seemed to rev quicker. and it did sound better; you really hear the engie sucking air on the Evo; air in easier, engine revs quicker and the turbo responds faster.

Ordered K&Ns for my new to me 08 S last week. i like the sound of the engine, and not having to change filters as often. over the long run, it'll be cheaper. slightly improved fuel economy is nice, but i didn't buy the pig for her good fuel mileage. I will say that the current paper filters don't seem to be hindering airflow, but we'll see when i install the K&Ns.

InvisibleD

Interesting topic.

I have used aftermarket filters and induction kits in the past on my cars with varying levels of success.

I have an induction kit on Evo IX for example and that makes a difference but then again thats a turbo engine and the original OEM setup is a little restrictive and can be enhanced.

If the 4.5S already has more air flow than needed as standard I think the only benefit in changing for a K&N oiled filter would be to hopefully minimise dirt over standard filter and secondly for a nicer noise!

In my experience power improvement, if at all, will probably be minimal - sometimes it can be worse as it messes with the MAF settings.

However, I have not used on a Cayenne so can not comment but not too costly to try it out I guess

kosmo

get a exhaust instead.

4ocious

I using K&N's with my Fabspeed secondary CAT delete exhaust. When combined, there is a noticeable difference; throatier, better acceleration, and slightly improved gas mileage. I've used K&N's in all my previous performace cars for the past 25-30 years and NEVER had a problem. I would use them in my 911TT but they don't make one so I've installed a BMC filter. IMO the myth that oiled filters cause the MAFS to go bad and CELs to light is just that, a myth. Go for it.

spooltime

This debate has raged on for many years now. Below is a repost of test results done by Jim Conforti, a very prominent BMW tuner back in the day. I have no reason to believe his testing results would be different today. The oiled filter debate might make sense when you have a track car that your attempting to extract the last shred of performance out of. But for a huge, heavy SUV? Really? Stick with the stock air filters; they're more than adequate for the engine's air flow.

"From a Bimmer site... Food for thought... Let the games begin...

Jim Conforti (AKA the Land Shark) did some testing:
This was a scientific test, not one done by filter manufacturer X to show that their filters are better than manufacturer Y. The test results are pretty irrefutable as the test lab tests and designs filters where "screw ups" are absolutely NOT allowable (I can't say any more for security. Think "Glow in the Dark").

A scientific test was done on TEST filters where air was loaded with ACCTD (some standardized "test dust" called AC Coarse Test Dust) and sucked through the TEST filter then through an analysis membrane. From the Quantity of dust injected and the amount that gets through the TEST filter and is then captured on the analysis membrane we can calculate the efficiency of the TEST filter in Question.

BMW Stock Filter, Eff. Area of Media: 8.4 sq ft.
K&N Replacement, Eff. Area of Media: 1.6 sq ft.

The filters are the SAME size. They both fit in the STOCK BMW M3 airbox. The difference is that the STOCK filter has 65 pleats 1.5" deep and the K&N only 29 pleats each 0.75" deep.
Now, remember this ratio: " 5.25:1". It's the ratio of the AREA of STOCK to K&N. It's very important and will come into play later.

The STOCK filter efficiency started at 93.4% at 0 loading and increased to 99.2% efficiency as the loading increased to a max tested of 38.8 gm/sq ft of dust.


The K&N filter efficiency started at 85.2% at 0 loading and increased to 98.1% at the max tested loading of 41.38 gm/sq ft.

Now, I hear you. "Jim, that's only a FEW PERCENT". But is it?

Let's look. If we had 100 grams of dust on a new BMW filter we would let through a total of 6.6 grams of dust in. If we used the new K&N filter we get 14.8 grams of dust. That's 224% (TWO HUNDRED TWENTY FOUR PERCENT!!) more dust ingested initially, stock vs. "free flow" and this ratio is pretty much held. Somewhere between 200-300% more dirt gets "ingested" anywhere across loading equivalence. The more INTERESTING thing is when you look at what happens to the DP or Differential Pressure at a constant airflow as you dirty both filters equally with time.

The test used a rate of 75gr of dust per 20 min. Here's where the AREA difference comes MAJORLY into play. See, even though the BMW filter flows a bit less at the SAME loading, it also LOADS UP 5.25 times SLOWER due to it's LARGER effective area. So what happens is that the K&N initially flows better, but as the dirt continues coming in, the K&N eventually flows WORSE while still letting MORE dirt in.

Now, does any of this additional dirt cause problems? I dunno. I suppose we could have a few people do some independent oil analyses on different motors using both K&Ns and Stock filters. Get enough of them, and you'd have a good statistical basis. For me though, it's simple: More DIRT = BAD.

The additional short-term airflow might make sense on a track car. IMHO, it doesn't for the street.

-- Jim Conforti"

DWPC

No way. Don't fall for the hype.