Toyota 8AR-FTS 2.0T Engine Specs and More
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.
8AR-FTS Engine Problems and Reliability
The new 2.0L turbo engine with direct injection combines the successful and time-tested solutions used in similar powertrains, which have been produced by other manufacturers for past 5-10 years. For example, a built-in exhaust manifold lowers the temperature of the exhaust gases and, as a result, the heat load and wear of the turbocharger. The presence of the additional fuel injection in intake ports successfully fights against a carbon build-up on the intake valves and walls of the intake channels.
But do not discount the fact that the engine has a rather complicated design with a lot of electronics. A striking example of that is that the engine has not 1 and not 2 but 3 thermostats. And as you know, the more components and electronics - the less reliability in general.
For example, some Lexus 200t owners are faced with a difficult to diagnose problem associated with a failure to respond to the accelerator pedal after several quick accelerations. In most cases, the problem was solved by full resetting of the software or completely replacing the engine control unit. The turbine bypass valve may emit sounds. It is also the cause of unstable engine operation at high speeds causing dips in power. This problem relates to the engines of the first 2 years of production (the manufacturer already has replaced this valve with a new smaller one).
Summing it up, we can say that the reliability of the 8AR-FTS engine is comparable with the newest 2.0TSI GEN 3 from the Volkswagen. Engine life is about 150-200k miles (mostly limited by engine block longevity).
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