In Reply to: 180k miles on a K&N ! posted by Mark.C on August 29, 2001 at 02:48:12:
Very anecdotal (but that seems to be the only kind of data you find for and against the filter!)
Anyway in my case, it was a K&N drop in filter. It was added at about 50kmiles (it's the second K&N filter). Use regular dino juice (10-40 or 20-50 castrol) Use BMW filters and BMW coolant. Run Chevron Premium gas. Car uses no oil between changes (~every 3K miles). There were two plug changes (stock BMW plugs) Filter was cleaned every 3-4 oil changes and relubed with K&N filtercharger kit.
No, I did not notice any real improvement in horsepower. G-Tech meter did not show anything that I would not attribute to random environmental error (ie 1-2 horsepower gain/loss is in the percentage of error). I did like the intake sound of the K&N filter. Even better sound from the K&N on the Miata (K&N Cone filter on cold air induction - that gets some extra horses) and the Mustang (K&N open filter - that gained a few). Basically, I found on my few examples that the drop in K&N was more of a convenience (not having to replace filters) while the cone and open element had a better chance at increasing HP (but not by much).
Just one data point. Not enough to plot a curve.
Don this is a very interesting post !
This is what’s known as anecdotal evidence and I’m interested as part of my reseach.
You say "The 535i had over 180K miles with the K&N and still uses no oil between changes, has strong compression and great idle."
What sort of filter was it drop in etc…and how did you maintain it over those 180k miles -cleaning etc ??
Probably right through the engine. Have you seen velocity numbers for airflow through an intake and exhaust? Next time you change the plugs, have someone crank the engine while you hold a hand near the spark plug hole. The blast of air will amaze you (did me at least first time I tried it). And that's just at cranking speed. I expect that an itty bitty dust partical would blow right on through.
Now dumping a handfull of sand, well that's a different story, but we aren't talking that story. The amount of dust passed by a K&N doesn't seem to negatively affect the cars I've had them on in the past. The 535i had over 180K miles with the K&N and still uses no oil between changes, has strong compression and great idle.
02 Mercedes C240 (no K&N)
95 540i (no K&N)
95 ///Miata (K&N)
87 Porsche 928 (K&N)
86 535i (K&N)
81 Mercedes 380SLC (no K&N)
71 Mustang Mach1 (K&N)