The M20A-FKS engine has the same design as a 2.5-liter version – A25A-FKS. The engine block is aluminum, open-deck type with sleeves cast directly in the cylinder block. Comparing to the A25A, the M20A has a smaller bore size by 7 mm and reduced stroke from 103.4 mm to 97.6 mm. The 2.0L version also got new tumble-maintaining shaped lightweight pistons with improved piston skirt surface enhancing oil retention, and three oil jets for each piston providing additional lubrication and cooling. Connecting rods are made of high strength steel.
The M20A has an aluminum cylinder head with four valves per cylinder and double overhead chain-driven camshafts. Intake side has laser-clad intake valve seats; the exhaust valve seats are pressed. The timing chain is a light-weight, single-row roller chain with a small pitch of 8 mm. Intake and exhaust camshafts are placed in a separate casing mounted on top of the cylinder head. Camshafts have the concave profile increasing valve lift amount. The engine is equipped with hydraulic tappets as well. The engine also features the newest Toyota’s Dual VVT-i, with VVT-iE (Variable Valve Timing-intelligence by Electric motor) on the intake side and simple VVT-i (with a conventional hydraulic actuator which uses an oil pressure to control variable timing) on the exhaust.
The M20A-FKS is equipped with Toyota’s D-4S fuel-injection system. It uses a combination of high-pressure direct-injection and low-pressure port fuel injection. The high-pressure six-hole fuel nozzles installed inside cylinder head injects fuel directly inside the combustion chamber of each cylinder. The port injection uses ten-hole low-pressure nozzles. The ECU decides which method of injection is preferable and optimal based on driving conditions, loads, and rpm to optimize combustion. The intake system includes Toyotas ETCS-i (electronic throttle control) and simple plastic intake manifold without any geometry change devices. Ignition is the latest DIS-4 with individual ignition coil for each cylinder. Instead of Denso FC16HR-Q8 in 2.5L version, this engine has FC20HR-Q8 spark plugs. To compliant with Euro 6d, the engine was equipped with a particulate filter (GPF) similar to DPF for diesel engines.
If you want to find detailed information about all major components and systems, read our full review on the A25A-FKS engine.
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