Not sure how accurate this info is going to be, but according to the wiki, the 2015 NSX will sport a 2.1L 90 degree V6 with DOHC labelled a Z21A.
C-series - 90° DOHC
1991–1996 3.0 L C30A (NSX)
1997–2005 3.2 L C32B (NSX)
EarthDreams Z-series - 90° DOHC
2015+ 2.1 L Z21A(EarthDreams) 2015 Acura NSX