EJ204 Subaru EngineThe Subaru EJ204 was a 2.0litre horizontallyopposed (or 'boxer') fourcylinder petrol engine with double overhead camshafts. The naturally aspirated E204 engine was initially introduced in the 2005 Subaru GD/GG Impreza and 2006 Subaru BL/BP Liberty as a more powerful alternative to the single overhead cam EJ202 engine, but effectively replaced the EJ202 when the GE/GHEJ201 and EJ202 Subaru EnginesThe EJ201 and EJ202 engines had an aluminium alloy cylinder head with crossflow cooling. Unlike the EJ20 engine, the intake ports for the EJ201 and EJ202 engines created a ‘tumble swirl’ motion for air as it entered the cylinder for better mixing of the air and fuel for more uniform flame travel and faster combustion.pcbn inse