From the very beginning, at the heart of the Subaru WRX has been the EJ-series engine. However it has been replaced with the 2.0 litre Direct-Injection Turbocharged FA20DIT engine in the 2015 and 2016 WRX, which uses the boxer formula we all know and love from Subaru, but is more efficient with better fuel economy, lower exhaust gas emissions, and most importantly more grunt.
Watch the new FA-series engine being manufactured at Subaru:
Direct Injection (DI) delivers fuel at 150MPa, or 150-times atmospheric pressure, directly into the engine’s combustion chamber instead of premixing it with the air in the intake port as in conventional engines. With this method, the timing and volume of fuel delivery to the combustion chamber is no longer dependent on the intake airflow and valve timing, thus making engine performance more predictable and precise.
The air-fuel mixture in a DI engine is not uniform, but instead has pockets of different air-fuel ratios. A richer mixture can therefore be generated close to the spark plug to ensure ignition. Direct Injection of the fuel cools the combustion chamber due to the latent heat of vaporisation of the fuel and makes it possible to raise the knocking limit, which is a major factor dictating the performance of turbocharged engines. This means that a higher compression ratio of 10.6:1 can be used in the FA20DIT to improve the engine’s efficiency and create better power.
The FA20DIT engine gets the best power and torque characteristic possible via Subaru’s Dual Active Valve Control System (DAVCS), which varies the inlet and exhaust timing of the engine allowing it to make 197kW of power at 5,600RPM and 350Nm of torque at 2,400RPM-5,200RPM.
Watch as professional racing driver Dean Herridge explores the 2015 WRX and experiences the FA20DIT engine:
DAVCS is a huge part of the FA20DIT engine, and it’s something Subaru are really proud of. It works by varying the timing of the intake and exhaust valves of the engine via an electronic control system to ensure optimal intake air induction and exhaust gas scavenging at all engine speeds and operating conditions. The graphs above show the timing variations during different situations for each engine cycle. This produces wide ranging benefits in terms of power output, fuel efficiency and exhaust gas emissions especially when combined with the advantages of the Direct-Injection engine.
For more information about the all-new 2016 Subaru WRX and WRX STI visit: http://www.subaru.com.au/new-wrx-and-wrx-sti
11-09-2015, 06:41 AM
The new FA20DIT – Performance and Engine Technology
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