• CYLINDER BLOCK
The difference between the left and right bank block height on the EJ is 0.1 mm. This difference was reduced on the FA20 engine to 0.05 mm. Most of Japanese flat or V-configuration engines have higher block height on the left bank. The reason being is that the water pump is usually on the left bank, so this slight different helps to offset the disparity in growth due to the temperature variance.
FA20 Cylinder Block Height: L = 205.05 mm R = 205.00 mm
The FA20 uses a split-type oil pan, allowing more space for the connecting rods during assembly. This also increases the rigidity of both the left and right banks. The fitment of the dowel pins is also deep and secure.
The crankcase bolts can only be installed and tightened from the right bank side during assembly, and there are no seal washers used. Since the cylinder bore size is smaller than the EJ variant, there is more room for the water jacket. Based on the engine’s bore spacing and oversized head gasket, it seems likely that Subaru may release a version of the FA20 with a larger bore size in the future.
Unlike other engines these days, the piston is not lower than the deck surface. It is nearly zero or a bit above the deck.
The EJ cylinders’ upper side was slightly tapered for ease of piston installation. In contrast, the FA20 however does not have much taper. The reduction in taper is designed to minimize detonation.
The FA20 incorporates two blow-by separators. One is located in the front left bank, while the other is at the rear right bank. These separators control the pressure in the crankcase via the crankcase’s blow-by galleys which lead to the sump. Hence, a forced-induction setup with this engine may increase blow-by and oil consumption.
Room is limited within the crankcase since the waterlines and blow-by galleys are housed in the crankcase as well. There are three main bearing sizes offered. Main bearing clearance is specified between 13/1000 – 31/1000 mm (0.0005 – 0.0012 in.).
The cylinder bore spacing is the same as the EJ at 113 mm.
Crankcase torque spec:
35N・m (357kgf・cm)→0N・m (0kgf・cm)→35N・m (357kgf・cm)
#3•4•5•6- 0 N・m (0kgf・cm)→17N・m (173kgf・cm)→60°
#1•2•7•8•9•10- 0 N・m (0kgf・cm)→17 N・m (173kgf・cm)→60