The 8AR-FTS engine is a 2.0-liter turbocharged direct-injected gasoline engine of the four-cylinder AR engine family. It debuted in 2015 in the Lexus NX 200t and became the first Toyota’s turbocharged power unit in a series of new engines with significantly improved thermal and fuel efficiency by using direct injection, cylinder head with the integrated exhaust manifold, and advanced turbocharger control. The engine itself is very similar to the naturally aspirated direct-injection 6AR-FSE engine but nonetheless has unique features and differences.

The 8AR-FTS engine has an open-deck, midi-skirt aluminum cylinder block with ‘spiny type’ cast iron cylinder liners cast in the block material. The engine block is equipped with a twin gear-driven counter-rotating balance shafts, fully balanced forged steel crankshaft, high-strength steel connecting rods, and lightweight aluminum pistons. Pistons are cooled by piston-cooling oil jets controlled by the ECM depending on external conditions to improve durability. There is a variable discharge oil pump increasing engine efficiency as well.

The cylinder head design of the 8AR-FTS includes an integrated four-into-two exhaust manifold. The exhaust manifold has two separate exhaust ports: one is for cylinders 2 and 3, second – for cylinders 1 and 4. The new aluminum cylinder head also has 16 valves and two overhead camshafts (DOHC) driven by a roller timing chain. The valvetrain got roller rocker arms and hydraulic lash adjusters for constant zero valve clearance. While the exhaust timing is adjusted by VVT-i, the intake camshaft rotation is controlled by Toyota’s ‘Variable Valve Timing – Intelligent Wide’ (VVT-iW). The combination of the VVT-i and VVT-iW allows the engine to operate in two different cycles – Otto and Atkinson cycles. According to engine speed, the engine switches between them for maximum fuel efficiency and power. The intake camshaft has additional 4-lobe cam driving a high-pressure fuel pump mounted on top of the cylinder head. The exhaust camshaft also does an extra job – it drives a vacuum pump.

The 2.0T 8AR-FTS engine has a twin-scroll turbocharger designed by Lexus (Miyoshi plant). Exhaust gases are supplied to the turbine wheel via two separate channels at different angles, providing the ability to eliminate a variable geometry mechanism, at the same time also a slight increase in efficiency. The maximum boost pressure is around 1.17 bar (17 psi). An air-to-liquid intercooler is mounted directly to the engine before the intake manifold. The engine speed is controlled by ‘Electronic Throttle Control System – intelligent’ (ETCS-i). Like the 6AR engine, the 8AR-FTS has combined fuel injection – direct injection into the cylinders and conventional port injection. The Lexus calls it as ESTEC D-4ST (Economy with Superior Thermal Efficient Combustion Direct injection 4-stroke with Turbo). Depending on engine speed, the system uses both types of injectors or direct injectors only.

As mentioned above, the 8AR-FTS is the first new gasoline turbo engine, released after a long period since the production of the 3S-GTE and the 1JZ-GTE. But the manufacturer didn’t stop on it and continued that series by a small turbocharged engine – the 1.2T 8NR-FTS.