I just want to preserve this link for the future. It triggered a discussion on the 928S4vr message board, that will disappear in a few weeks...

http://www.mcagraphix.com/filter/test.htm

 

Nicole,
I distinctly remember seing a dyno test on a 928 in which the K&N air filter caused a reduction in power. I'm really not sure that the test done on the site to which you link is relevant.

 

In addition, for our cars with the Hot wire MAS, there is the possibility of oil residue on the wire that will be baked on rather than vaporized during the burn off cycle leading to early MAS failure. I for one will stick with the OEM filters.

 

Hi Nicole,
a good report thanks.

There is some evidence that the K&N filters have been shown to raise the silicate level in oil samples. This may be when they are new or just after cleaning - I don't know

It is also true that air filters get more efficient at trapping debris as they "get some miles under their belt". At the same time, they lose their flow rate efficlency. A catch 22 I'm afraid.This is especially so with the likes of the K&N type filters

Some synthetic fibre air cleaner elements are very very efficient - I know of none for a 928. I use such filters from Donaldson in heavy diesel engines - they are imported especially from the USA. And very expensive!

Regards

 

Louie Ott and Mike Schmidt have been here before. Can't figger out how to post the airbox mods but I'll email pics and dyno results to anyone who wants them. Email me at
cschreib@eesus.jnj.com and I'll send them over.

Approx 10hp and 10ftlbs/torque. Pretty damn good. They should sell it!!

 

Go ahead, Nicole,
Get it started again...
You can pick and choose...
Punch into your browser> K&N filter test data.
There should be pages of testimonials and damnation.
On one hand you can back up either side of the arguement with alleged fact, I say this because there are at least two conflicting arguments using the same test data.
There are arguements that the K&N actually restricts airflow and others demonstrating 35 to 141% increases in airflow. As mentioned by others when condemning the K&N their information was independently tested - by who, for what reason, what was thier gain or interest in the test? Then again, K&N also touts independant testing -same questions-.
Supposedly the test's are verified, the test procedures are the same, the particulates -medium- are the same, temp, humidity, alt. are the same, and the engine(s) are flowed for the same baseline CFM.
The Guy's who just did the SC install determined a negative on flow, and I'll trust them and the dyno results they provided.
I also firmly believe the hot wire oil coating problems on sHARKs with the wire(s) are real.
BUT...
I have used a K&N for several years now, I don't have a hot wire to worry about. I haven't had any problems with particulate pass thru -including leaves/bug parts. I haven't had any oil pooling in the intake area either.
I do believe over oiling or using the K&N right out of the bag -so to speak-
is a key contributor to the Hot wire/ restriction/flow/pooling problems but until I pick up a S4 stablemate for Pattycakes my suspicions will remain unsubstanciated.
BTW My reason for buying a K&N is strictly for longevity. You can clean it then PROPERLY oil and install it -seating is very important- and use it over and over for years.
This is important in the Permian Basin as our part of the country moves around -a lot- in the form of dust. Trust me you'd hate it here.
Dusting, wiping, sweeping, and shoveling Texas out of your home is a way of life here. So, obviously, it is a serious consideration when selecting a filter.
In my location/environment I made the right decision...period.

 

-The only advantage that I've ever noticed in having the K&N on two German cars is that it makes a cool sound when the throttle plate goes open.

I had a K&N on my 928 when I bought it, but removed it after hearing about the wire fouling problems....and discovering that the two sides of my wire were different colors. The side facing the filter was black...whereas the other side was shiny silver.

<--New MAF these days, and back to the original paper air filter. Only...the original has orange rubber around the edges, and I hate the way it looks!

Normy!
'85 S2 5 Speed

 

So you're saying that you live in an extremely dusty location, and your air filter decision was based on it being the cheapest possible option?

 

Pete.
Nice try.
The consideration was the least expensive that option that works!
We can play the: I can prove the K&N passes particulate matter 'A' in such and such quantity as indicated by test data provided by an independant tester. But oddly, the same tester is likely to also say that the K&N is more restrictive and will detail CFM flow tests PROVING that claim...Hmmm...so how does that work?
Similar to bug parts appearing on the wrong side of the filter as far as I am concerned. You can't have your cake nd eat it too.
Initially I installed the K&N with the factory shipping lube in place.
I think I could have stuck it on a brick wall and it would have stayed there.
This, I might add is the only time I had any discernable oil residue in the AFM throat. I have checked for debris and oil quite a few times since this arguement reared up about two years ago. Other than the initial inspection where I did not follow instructions nor to check for proper seating and once where I wasn't careful when I removed the filter there has been no dust and no oil residue -not even from the breathers/airpump/crankcase.
FWIW
I don't believe in the HP gain claims that K&N spouts off about either, though the easiy tricked seat of the pants sensor has me convinced that I had a tiny low end increase in torque.
So bottom line I have difficulty trusting test data from, both, detractors and supporters of the K&N.
I do have concerns with the oil coating of the 'hotwire - MAF-' and don't see any reason to discount the coating claim. Nor do I dicount the Dyno data provided by our resident bolt on SC team.
I do know that since my 4.5L doesn't have the wire its' of no concern to me.
I also know I'm not passing debis or particulate matter.
In "my case" the K&N is providing long term value, and it does it's job.
From the way you extracted the question from the enclosed quotes I can safely assume that you work for FOX News
"(seldom) FAIR and (rarely) BALANCED News

 

That works because the stock filter has a much greater filter surface area than the K&N. You can easily measure that, or just look at the two filters and count the number of pleats.
I wish more people would be skeptical of stuff like that. I'm a definite believer in doing your own testing to find out what the real results are, instead of trusting some marketing department. In addition to seeing others do it, I have done my own testing. My K&N is long gone.