While the cylinder block had an open-deck design, Subaru claimed that lowering the water jacket achieved the same block stiffness as a semi-closed structure.
In addition to preventing changes in bore shape, this design cooling around the deck surface and raised the knock limit..
Furthermore, roller lifters were used as contacts between the pump and camshafts to reduce friction; a pulsating damper was also integrated in the pump to reduce fuel pressure fluctuations.
The hydraulic lash adjuster — located at the fulcrum of the roller rocker arm — consisted primarily of a plunger, plunger spring, check ball and check ball spring.
The iridium-tipped spark plug caps, which provided contact to the spark plugs, were integrated with the ignition coil assembly.
Description: According to Subaru, fuel efficiency was improved by reducing coolant flow volume and retaining higher oil temperatures at the cylinder block walls.