N52 Engine codes

[thecookie125]

Morning all, I've seen a lot of reference to N52 black vs silver top engines. From what i'm reading the black top got an upgraded CCV system, water pump, crank and various other bits and pieces.

Mines an August 2008 bulid so it's one of the later engines with the code N52B30AF.

Does anyone know anything about what that code means over the standard N52B30? I've noticed that my red line is at 7,000RPM and doesn't have the dashes at 6750RPM like earlier N52's have .