K&N Air Filter

You may have warranty concerns also. There is a school of thought that the K&N doesn't filter out really fine particulates as a consequence of its higher volume of airflow (and if you suffered engine damage with a K&N installed Porsche would probably not honor any warranty in effect).

They're frequently implicated in Mass AirFlow sensor problems, to the tune of $500 replacement. I have yet to see an unbiased authoritative report that demonstrates that K&N air filters actually increase power. OTOH, there's NO doubt that they can coat your induction system with an oily film.

A new K&N filter, fresh out of the box, will not coat anything with oil. The problem occurs when some over-zealous owner decides its time to clean and re-oil his filter and gets carried away re-applying the oil. Bye, bye, MAF sensor.

John

Right. And who needs that kind of aggravation for what amounts to no demonstrable power increase?

Perhaps someone who thinks it is better in the long run to spend $70 once on a K&N rather than $20 every 6 months on a paper filter?

David Schultz assembled some bits to read:

You mean spend $70 once, then $500 once for the MAF and then $5000 once for the engine rebuild, right?

Check.

Check.

The $500 only comes into play if you apply too much oil (most 928s belch enough oil back up the intake at high revs that THAT is a more likely cause of MAF failure). The $5000 for the rebuild MIGHT come into play earlier than if a paper filter were used, but I would wager on a factor of $250k miles life versus $300k prior to rebuild. At that point, it is probably cheaper to part out the current car and purchase a less used example.

Check is in the mail of course :)