[flwbyu]

Well,



I have seen so much talk on this topic that I thought I would post a relevant article I found -



"The question posed in the title of this post is one that I’ve seen debated on the ‘net since discovering car-related email lists. Fortunately, a Duramax owner tired of the lack of scientific evidence pursued a path of testing that eventually ended with a lab performing the ISO 5011 procedure on a number of replacement air filters. The result was one that many might have concluded on their own - for a given size, a filter’s ability to trap dust is inversely proportional to its flow rate. If keeping dust from your engine is the goal, a paper filter such as an AC Delco will provide far superior filtering performance, but you’ll pay a price in airflow. If WOT performance is most important, the K&N filter used in this test provided about 50% less restriction to airflow, with the 1.6” of H20 difference in air pressure drop at 350 CFM making for a minimal difference (~0.5%) in power at this flow rate. The K&N and UNI filters were far less efficient at trapping dust, and note that they lose their flow advantage after filtering about 180 grams of dust. There’s also the economics of washable cotton filters, with a K&N providing a savings of about $285 over 250,000 miles. All of my vehicles currently run K&N filters, but this test has me re-thinking the use of them on daily drivers."



http://home.usadatanet.net/%7Ejbplock/IS...SPICER.htm

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[flash]

we keep seeing this same article pop up - it's very biased - they did a great job of manipulating the data and representing it in a way to suit their purposes



the idea is sound on the surface but it misses a big point



it's not about how much a filter grabs as it is what size of particulate is necessary to be grabbed



what it fails to tell you is that there is no measurement of particulate size that passes the filter or whether or not it is harmful



it also does not tell you if the K&N was properly oiled



the fact of the matter is that the K&N filters out everything that could be harmful, so any other filter that catches more is just bringing a loss in performance - there are larger particlulates passing your oil filter than pass the K&N air filter



yes, there are filters that catch more, but they are catching things that don't matter and cost you performance - there is such a thing as too much filter

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[Harvey]

I get the impression that most 928 owners are NOT fans of the K&N marketing hype filter...I'm sticking with the others. Then there's the stock Porsche and OEM debate with big difference in price. I'm not sure about performance though



Harvey

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[flash]

it's not hype - we tested the filter - it dramatically improved the performance on the bench and on the dyno on the 968



a few guys picked up a bit of info from somebody who made a mistake and then had a problem with the filter, and then spread that around



over oiling can result in problems - this is what happened - it gummed things up - that got around and suddenly there was a "universal" problem



this is the problem with using the internet as an information source and not actually talking to experts - somebody reads one little bit, takes it as gospel without any further research, and then runs off and tells the world - it's the worst case of "post office" i've ever seen



call K&N - they will be happy to tell you all about it

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[Harvey]

If that's the case, many 928ers have a bad case of "post office." The K&N concept sounds good though. I'd like to see a non-K&N sponsored review, along with the long term service. The oil could be a problem like you say. Too much if it hardening could actually restrict flow?



Harvey



[quote name='flash' date='Sep 8 2005, 07:49 AM']it's not hype - we tested the filter - it dramatically improved the performance on the bench and on the dyno on the 968



a few guys picked up a bit of info from somebody who made a mistake and then had a problem with the filter, and then spread that around



over oiling can result in problems - this is what happened - it gummed things up - that got around and suddenly there was a "universal" problem



this is the problem with using the internet as an information source and not actually talking to experts - somebody reads one little bit, takes it as gospel without any further research, and then runs off and tells the world - it's the worst case of "post office" i've ever seen



call K&N - they will be happy to tell you all about it

[right][post="9638"]<{POST_SNAPBACK}>[/post][/right][/quote]

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[flash]

it would not surprise me - these groups tend to pass around the same information like wildfire - take, for example, the ERRONEOUS post about the "ban" on HRE wheels - there is no such ban at all by anyone, yet the single post on an audi site got picked up on rennlist and spread as gospel in 48 hours - it will take a lot of clean up to get that information, and the impression the public had, corrected - unfortunately that kind of thing happens way too often



ours was a non K&N sponsored test of performance, but not filtration - somebody else is going to have to do that one - at this point i'm inclined to trust them though - i've been successfully using K&N filters for years

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[ds968]

I said this before, but I think it's worth repeating : Porsche dealers are very

"a-retentive" about non-oem products and for the most part have a cow anytime

a customer suggests that an after market product may be contemplated for use in a precious P-car... finding every fault with that product so as to discourage you from getting it. Sure, this is ostensibly to sell their stuff, BUT one of the few "working " parts you'll see at P dealers is the K&N filter. IMO, if they did not have the greatest confidence in the K&N product, no amount of promotinal dollars would be accepted by Porsche to push this filter in their showroom.



Also, I've had a K&N in my 944 and that car made it past 250,000 miles without any engine problems !! I have K&N in my 968, one in the MBZ, one in my Nissan and if they made one for the lawnmower I'd install it there too ! Ok, I meant the gardners' lawn mower, but you get my drift..





Hey, this is California - even if I wanted to cut my own grass I would be the ridicule of all my neighbors. Sheesh, the pressures of living in the Desperate Housewives neighborhood <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" /> But it has its rewards <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" />

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[Harvey]

A lot of items I've seen at Porsche dealers seem to be high-priced, high markup items. I'm not saying that the K&N isn't better though. I just haven't researched it enough to know for myself yet. Perhaps my next filter will be K&N.



Harvey



"one of the few "working " parts you'll see at P dealers is the K&N filter."

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