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Hello guys,
I see a few of you sporting K&N air filters and I wanted to share some information I’ve learned in my years of collecting exotics and some not so exotics. I presently own three Porsches (all vintage wasserpumpers), two Volvos, a TVR, and an Italian exotic investment grade automobile.
After purchasing two K&N air filters I eventually ran into a friend on a forum who had a car just like mine. It happened to be a 1983 928S 5-speed. I recommended a K&N air filter to him, and I received a surprising response from a Mr. Wally Plumley, former NASA Engineer, holder of two speed records at Bonneville Salt Flats, and presently associated with the reputable firm of 928 Specialists. http://www.928gt.com/928GT.htm
Wally advised me that they won’t sell the K&N air filter (any more) for three reasons: too much dirt gets through them, they don’t add any power to a 928, and they got way too many calls regarding drivability problems stemming from the oil on a K&N getting into the MAF system.
Upon hearing the news from a complete stranger at the time, I naturally question his information. He was polite, but firm. I checked independently, and found he was right. I am therefore sharing this information with this particular forum, along with a couple of links for your reading enjoyment.
In the end, I burned my K&N filters ceremoniously, and I took photos, ha ha. Since I have a variety of my cars published, some with engine shots sporting a K&N air filter, I’m trying to get the “word” out, that these filters will do damage to your fine machinery, and anyone (such as me) is a victim of the K&N marketing program if you bought one. I consider myself a “sucker” for having bought one, but now I know better, and I’m running “premium” paper filters that I buy from “reputable” firms such as 928 Specialists. I’m not in the automotive business, I’m just an enthusiast. I have no reason for posting this information, other than to spread what I believe is good information. Pay particular attention to the link where the racing team experienced premature leakdown problems. Then if you care to still debate, you should get in contact with the gentleman who races a FE Ford (427) who also runs a fleet truck line. He decided to try the K&N air filters to see if he could get better gas milage. The results were no additional gas milage, and increased silica (the equivalent to fine sand) in his oil analysis program. He stopped using the K&N filters and the silica readings on his oil analysis dropped.
I question the use of a K&N air filter on street machinery for several reasons. One, they are often used in a “cone” assembly, and all this does is place the air intake behind the radiator where it will suck hot air, and this is bad for performance. Two, why would I want to get zero to nil performance gain, as documented by many a dyno test, and then subject my fine machinery to additional dust ingestion?
I also have to question the motives of people who sell these filters to people who are going to use them on street driven vehicles. Certainly the motivation has to be profit. However, in the instance of 928 Specialists, they put profit aside due to what they believe is “better information” and what I call integrity.
Street driven vehicles normally have air boxes and filters sized far in excess of what the engine needs for cfm in the first place, and this is the reason we see zero horsepower difference from a dyno most of the time. For performance applications, where a 944 Porsche, for instance, has been tweaked for GTU competition, then yes, you will need something that flows better, lets more dirt and small bugs in, lets the motor develop that 600-hp for the duration of the race, and then needs to be torn down for new rings, valves, and bearings.
Submitted in good faith, for your reading enjoyment
Mr. P
http://forums1.roadfly.org/porsche/forums/924-944-968/4959457-1.html
http://forums1.roadfly.org/porsche/forums/cayenne/5147399-1.html
http://www.mcagraphix.com/filter/test.htm
http://www.performanceoiltechnology.com/k&nbitesthedust.htm
This is a test by AMSOIL, and I use their oil but not their filter. It is interesting that this test shows the paper air filter flowing better than the K&N and filtering out more dirt. I view this as just one more piece of evidence in which to make a decision.
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2004 XC90 2.5T AWD, 1990 944 S2 Cabriolet, 1989 740 GL 16v, 1984 944, 1983 928S 5-speed, 1974 TVR 2500M
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