• CYLINDER HEAD

The EJ cylinder head features a complex oiling system that likely required extensive manufacturing time. Whereas the FA20’s oiling system is much simpler, as the front cover now supplies oil to the camshaft carriers.

Lacking extreme narrow angles at the direct-injection position, the FA20 combustion chamber is very compact. The engine’s requirement to run at a high compression (12.5:1) with low-octane gasoline required a squish-area design of the combustion chamber along with a complex piston crown profile. The engine’s improved cooling performance (due to the cylinder block design) also reduces the engine’s propensity for knock.

Like many Toyota engines, the FA20 runs its water line on the exhaust side. After removing the cam carriers, the shallow water jacket is clearly visible. The cylinder head is simple and lightweight.

• HEAD GASKET

Edge Thickness: 0.5mm (0.020”)

Bore Seal Thickness: 0.55mm (0.022”)
Bore Diameter: 89.5mm

The head gasket is one of the thinnest found on a production engine. The gasket’s thinness allows for a tight squish clearance to be set. However, we feel that the 89.5 mm bore diameter of the gasket is too large for the 86 mm cylinder; typically, a 87 or 87.5 mm gasket would be used with a 86mm cylinder.

Head Bolts Torque Specs
20N・m (204kgf・cm)→100N・m (1020kgf・cm)→0N・m (0kgf・cm)
20N・m (204kgf・cm)→42N・m (428kgf・cm)→100°
→ Center 2x 100°: Outer 4x 50°

• PISTON

Because of the drop-in bore size, the smaller FA20 piston is 150 grams lighter than the EJ piston, while the FA20T piston is 50 grams lighter than the Mitsubishi 4B11 piston. However, the power handling potential of the pistons are suspect since the FA20 engine’s lack piston cooling jets or a cooling channel in the piston. While the FA20’s thinner second ring reduces friction and improves seal over a thicker ring, it may also be limited in its ability to handle the thermal stresses of additional power.

Both the FA20 and FA20T pistons feature a friction- reducing skirt coating. This coating helps reduce piston to cylinder wear on startup.

Unlike other direct-injection pistons, the FA20’s pistons feature a concave crown that is quite shallow. This allows the piston to have a better dynamic balance. FA20T pistons feature an asymmetrical skirt design that is better suited for high-compression boxer engines.

The crown of the FA20 versus the FA20T piston is much different.

Piston clearance is extremely tight at
10/1000 – 30/1000mm (0.0004”-0.0012”)

Piston grades are two types of standard, 0.25 mm oversize and 0.5 mm oversize The oil ring can only be installed one way. It has a stopper, and it can only be installed one way.

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