The 370Z has a lot of power, but there's more to going around a track then power
The NSX-R weighs about 2800 lbs, versus the 3340 of a 370Z while making 290HP (manufacturer's claim - some speculate more) versus the 330 of the 370Z, with an excellent torque curve (though the 370Z is nothing to sneeze at).
In a straight line, the NSX-R stock is 12.7 sec in the 1/4, so faster than my automatic 370Z
So it's not surprising that it is faster than the 370Z on a track.