Porsche Cayenne V6 2008 Service Information page 54

Fuel, Exhaust & Engine Electrics
Structure of the surface gap spark plug in the
Cayenne S:
1 - Surface gap
2 - Ground electrode
3 - Centere electrode
4 - Insulator Cayenne Turbo spark plugs
Page 2.24
Cayenne S Spark Plugs
The V8 naturally aspirated engine has nickel-yttrium spark plugs with
four ground electrodes, which must be changed every 36,000 miles
(60,000 km) or after 4 years according to the Technical Manual.
The four ground electrodes are arranged around the ceramic insulator in
these surface gap spark plugs. The sparks -1- cross the surface of the
insulator -4- and arc across a small gas gap to the ground electrode
-2-, which improves the ignition properties. The main advantage of the
surface gap spark plugs is the self cleaning effect of the insulator foot
tip, since any shunts that occur between the center electrode and the
ground electrode through the surface gaps, in particular during a cold
start, are eliminated.
Cayenne Turbo Spark Plugs
The V8 turbo engine has air gap spark plugs with one double-platinum
ground electrode, which must be changed every 24,000 miles (40,000
km) or after 4 years according to the Technical Manual.
Note
Spark plug replacement intervals have changed for M.Y. 2008 when
compared to the 2003-2006 Cayenne models.