2012 Subaru Impreza with 30% fuel economy improvement uses BorgWarner variable cam timing technology
BorgWarner’s Cam Torque Actuated (CTA) variable cam timing (VCT) technology (earlier post) with new mid-position lock system (earlier post) helps improve fuel economy for the 2012 Subaru Impreza. According to Subaru, the 2012 Impreza offers 30% better fuel economy compared with the previous model year.
The 2012 Impreza is powered by a new four-cylinder 1.6-liter Boxer engine (available in Japan only) and 2.0-liter Boxer engine (available globally) which meet US Super Ultra Low Emissions Vehicle (SULEV) and Euro 5 emissions standards.
BorgWarner’s patented CTA technology takes advantage of the existing torsional energy in the valve train to phase the camshaft, similar to a hydraulic ratchet. Compared with traditional oil pressure actuated cam phasers, CTA cam phasers operate more quickly and under a wider range of engine speeds and temperatures, enabling engines to run more efficiently at all engine speeds with faster response. BorgWarner received a 2009 Automotive News PACE Award for this technology.
BorgWarner’s latest advancement in CTA technology is the new mid-position lock system, named a finalist for a 2011 PACE Award. Because conventional systems default to one end of the camshaft phaser’s range of angular travel, calibration strategies are limited by the restricted amount of travel that can be designed into a variably timed system.
BorgWarner’s mid-position lock technology defaults at an intermediate position to allow for a greater range of travel and more control over airflow for improved fuel economy, function and efficiency. A patented hydraulic circuit passively moves the system to the mid position for reliable repositioning in nearly any potential engine operating condition with no added active relocking control.