Less Displacement, More Torque
To power the new WRX, Subaru plucked a unit from its latest FA20 family of engines. The WRX’s new FA20 Direct Injection Turbo (DIT) engine features a Subaru-designed direct injection system and intercooled boost pressure by way of a twin-scroll Garrett MGT22 journal bearing turbocharger positioned just below the crankshaft. The Active Valve Control System (AVCS) on both the intake and exhaust cams now operates over a wider range, and the valvetrain features roller rockers.
Thanks in part to its direct injection fuel delivery system, the output and efficiency are both increased by the FA20. Despite its smaller, two-liter displacement, it produces three additional horsepower and 14lb-ft of additional torque at 15.9psi boost pressure, outperforming the retiring 2.5-liter EJ255.
According to Subaru, the new FA20 gets an estimated 21 city/28 highway fuel efficiency, while the EJ255 was estimated at 17 city/23 highway.
In addition to upgrading the powerplant of the WRX, Subaru developed new driveline options as well. For the first time, a six-speed manual is now standard equipment for the WRX, while an optional, Sport Lineartronic Continuously Variable Transmission with Si Drive performance management is now available. Both of these drivelines benefit from Subaru’s new Active Torque Vectoring (ATV) technology.
Active Torque Vectoring
[pullquote]ATV HELPS TO IMPROVE HANDLING BY ADDING… TORQUE TO THE OUTER FRONT (TIRE) FOR IMPROVED TURN-IN[/pullquote]What is Active Torque Vectoring (ATV)? ATV helps to improve handling by adding braking force to the inner front tire and adding torque to outer front for improved turn-in and reduced understeer. ATV works in conjunction with the Vehicle Dynamic Control (VDC, aka traction control) system.
In the WRX, the VDC has three different modes: on, off and traction mode. On activates both VDC and ATV, while off deactivates both. The traction mode, which deactivates the VDC but retains the full function of the ATV, is ideal for the road course or racetrack.
Six and a Stick
The new six-speed manual transmission features a cable-linkage system to connect the driver to the gears. The first five gears are more closely spaced, while the sixth gear is more of an overdrive gear to provide improved fuel efficiency while cruising. First and second gears feature carbon synchros for durability and smooth shifting.
The manual transmission benefits from Subaru’s Continuous All-Wheel Drive system with a viscous-coupling, locking center differential. This mechanical system features a nominal 50:50 split, but will automatically send more torque to the wheels with the best traction.
CVT, but Better
The Sport Lineartronic Continuously Variable Transmission (CVT) is based on the Forester’s automatic CVT unit. However, the WRX version comes tuned for sport driving. The Sport Lineartronic transmission is adaptive and adjusts with your driving style for both performance and for efficiency. The SI-Drive performance management offers three different modes: I, S, S# (# = sharp.) In the “I” mode, the CVT aims for efficiency. In the “S” mode, the transmission functions as a six-speed automatic. In the “S sharp” mode, the transmission becomes an eight-speed close-ratio transmission. Throttle response is sharpened with each heightened mode, and regardless of what mode you are in, you can activate the Launch Mode. The automatic transmission relies on Subaru’s Variable Torque Distribution (VTD) all-wheel-drive system to distribute torque to the wheels. A planetary gear-type center differential with an electronically-controlled hydraulic transfer clutch splits torque front to rear at a nominal 45:55 ratio.