TOMEI POWERED Dissects the FA20 | Flat Four

• CONNECTING RODS

Connecting rods for the FA20 engineThe design of the connecting rods is mainly for ease and speed of mass production. Strength and balance is questionable. The face mating between the rod and cap is the new “zigzag” type. This zigzag design prevents the end cap from being assembled the wrong way and reduces the sheer forces on the rod bolts.

Three grade sizes of bearings are made available.
Bearing clearance 25/1000 ~ 55/1000mm (0.001”- 0.0022”).

Connecting rod bolt torque specs
10N・m(102kgf・cm)→25N・m(255kgf・cm)→92.

ConRod Weight Cap Weight
FA20 346.8g 112.3g
FA20T 370.9g 120.7g
Bolt Diameter M9.5-1.0mm Distance between Centers 129.3mm

• CRANK PULLEYCrank pulley for the FA20 engine

Crank Pulley Torque Settings
20N・m (204kgf・cm)→90°
Torsion Damper Only

• CRANKSHAFT

Historically, engines that evolved to have longer strokes also had an increase in the crankshaft’s main journal (pin) diameter. However, the FA20’s evolution took a different route, as the crank pin became smaller than in the EJ. Perhaps, this is a result of the FA20’s connecting rod design or the crankcase’s limited internal space. Another possibility is that the engineers may have opted to have thicker main webbing in the block.

Main Pin Stroke
FA20 68φ 50φ 86mm
EJ20 62φ 52φ 75mm
While the FA20 uses larger diameter main journals, rod journals have shrunk in size.Crankshaft for the FA20 engine

• OIL PAN

The trochoid shape of the oil pan has slightly changed; whereas the outer dimensions are almost unchanged. One drawback is that the position of the oil filter is too far from the main galley. Ideally, the oil filter would be positioned on the main galley. Under conditions of high loads and low engine speeds, a significant move of the VVT devices could potentially cause an unwanted drop in oil pressure.

There are two oil drainback lines from the intake plenum to the sump, via the Positive Crankcase Ventilation (PCV) valve suction pipe and blow-by separator. We found this design interesting, since it is different from the conventional designs.

Oil Pump GearOil pump gears for the FA20 engine

Outer Dia. Tooth Thickness
FA20 76.85mm 10mm
GDB 77.8mm 10mm
GRB 77.8mm 12mm