Air filter failure? Anybody had one?
 

I noticed a small difference in engine noise at low speeds then when accelerating over 4000 rpm the noise rapidly increased a ton, into a power roar with some kind of "flapping sound". It is not an exhaust noise.
Did my filter fail? If yes, has anybody else experienced this?

Never happened to me, just open up the engine hatch and check your filter!

Variocam advances can timing substantially at 5500rpm and this significantly accentuates the"intake roar". Vibrational noises, however, are not normal.

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I've driven Boxsters since 2004 and am very familiar with the sound of the engine over 4000. This is something new and very different.

The only filter I've had fail was one of those foam types. It cost me an engine on a race car. Stock only on everything now.

I have never seen a good filter fail bit I have on another older car the intake hose collapsing in.

Are you sure it's not the VTEC kicking in, yo?

I've driven Boxsters since 2004 and am very familiar with the sound of the engine over 4000. This is something new and very different.
And yes I'm familiar with the result of hitting the rev limiter. This is different, you can be sure.

Did you open the air box and look?

Good question so I'll share with you about my getting to the engine. First, I had to respect the 20 rule which says the temp. has to be within 20 of my age and since I don't live in CA or FL, that took a few days. I watched a video and got to the engine cover but the Torx bit I had was the wrong size so I researched and went out and bought one marked T40. It didn't work so I researched again and another site says T-30-damned.

Before returning to the store I want to make sure the T-30 is correct. After that, I'll take a look and let you know. :dance:

Accessory belt been changed recently?

Serpentine belt was changed several years ago.

Not the air filter
 

I was able to confirm that it is whole and looks healthy. The hunt continues.

I have the IPD plenum, 74mm throttle body, sportfilter and desnorkeled to boot --> 2.7l engine.
Accelerating over 5000 rpm creates such an intoxicating power roar, so massively loud, that you believe you are driving Steve McQueen's 917 in "le mans".
An hour on the autobahn and you are deaf, but still smiling.
So, you are not alone. :cheers:

P.S.: Forget about sport exhausts ;)

Mystery solved
 

Air filter checked out A-OK so I reinstalled the plastic cover with care.
A high rpm highway test proves that the strange roar with a flapping sound is gone.
I believe the air filter cover was not securely attached at the bottom (two screws attach at the top-2005 S). If all my issues were so easily found and fixed............:)