VQ Power valves

[02silverpathy]

Anybody here with a VQ ever hear those powervalves shut after like 45oo rpm's?? Listen to your intake, during hard throttle, long rev you will hear the intake go from deep growl back to mild somewhere near 5k.....anybody have any good info here?? I have 1 theory but I want others thoughts first.

[Orangetang]

My guess would be Nissan's N-VCT, VVL/VVT or whatever our VQs have. Either the cam rotation, timing, or valve duration is shifting, similar to V-Tec in a Honda??I have noticed the 4500rpm note change since the first time I drove mine. Always assumed it was some sort of fuel economy/power related Nissan V-Tec.

[Trainman]

Ah, the variable valve timing sounds like the answer. Yes, I hear a change then too, and have always put it down to the VVT. Our Sienna also has VVT and it does the same thing.

[nissandoms47]

Probably just those valves closing.

[asrautox]

LOL, you should hear it with a K&N CAI.. I always thought it was the intake manifold..