No, the 911 engines, starting with the type 901 air-cooled version, have always driven the camshafts via chains, either from an intermediate gear or shaft. This trend continues with the introduction of the latest Carrera models that now use direct fuel injection.
The 2010 Porsche 911 has double overhead cam (DOHC).
The 2008 Porsche 911 has double overhead cam (DOHC).
The 2006 Porsche 911 has double overhead cam (DOHC).
The 2002 Porsche 911 has double overhead cam (DOHC).
The 2007 Porsche 911 has double overhead cam (DOHC).
The 2004 Porsche 911 has double overhead cam (DOHC).
The 2005 Porsche 911 has double overhead cam (DOHC).
The 2003 Porsche 911 has double overhead cam (DOHC).
The 2013 Porsche 911 has double overhead cam (DOHC).
The 2001 Porsche 911 has double overhead cam (DOHC).
The 2012 Porsche 911 has double overhead cam (DOHC).
The 2014 Porsche 911 has double overhead cam (DOHC).