EJ251 and EJ252 Subaru Engines
The EJ251 and EJ252 engines had multi point sequential fuel injection and centrally located spark plugs. The EJ251 and EJ252 engines had two ignition coils (one for each pair of cylinders, i.e. 1 2 and 3 4) which fired the spark plugs directly twice per cycle.
FA20E and FA20F Subaru Engines
The FA20E and FA20F engines have a cast aluminium alloy cylinder head with chain driven double overhead camshafts per cylinder bank. The four valves per cylinder – two intake and two exhaust – were actuated by roller rocker arms which had built in needle bearings that reduced the friction that occurred between the camshafts and the roller rocker arms.