Furthermore, the crankshaft journals were made from aluminium and cast iron due to the high pressure applied on both side of the cylinder block.
Initially, the turbocharger was positioned under the engine.
Furthermore, the intake ports and the diameter of the intake valves were designed to create a swirling effect for the air as it entered the combustion chamber.
According to Subaru, fuel efficiency was improved by reducing coolant flow volume and retaining higher oil temperatures at the cylinder block walls.
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.
Specifications for other markets may vary.
According to Subaru, higher strength material for the connecting rod bolts enabled higher pressure to be withstood in the cylinders.