news from across the pond...
not t a completely new engine, rather heavily revised from the last version, as it is over 85% new. This is the same engine that was announced for the new G35 sedan, and at the time was only said to put out 310 hp (again not a big bump in HP, but rpms have increased by about 1k).
NISSAN announced the following specifications:
* New design cylinder block. The rudder frame was added, rigidity was raised substantially.
* Left and right complete symmetrical inhalation and exhalation air system
* Decreasing the friction worldwide first hydrogen free DLC (Diamond Like Carbon) with coating.
* Setting electromagnetism VTC on exhaust cam side in addition to the oil pressure VTC of air inlet cam side.
* Isometric exhaust manifold
Only the '07 G35 and '07 350z will have the new VQ35HR motor.
This new engine has increased response and rpms, this allows it to max out at the 7500 rpm redline ("HR" most likely meaning High Rev or Higher Rev) vs 6600 rpm (on 2006 and older 350z) and have improved top end power.
More information can be found here, scroll to the bottom:
http://www.nissannews.com/nissan/news/products/20060712121701.shtml