VCT?? How Does It Work??
Variable Camshaft Timing (VCT) is an automobile variable valve timing technology developed by Ford. It allows optimum engine performance, low emissions, and high fuel efficiency when compared with the engines with fixed camshafts.
The power train control module (PCM) transmits a signal to the solenoids to move the valve spool that regulates the flow of oil to the phaser cavity. These oil control solenoids are bolted into the cylinder heads towards the front side of the engine close to the camshaft phasers. It utilizes electronically controllable hydraulic valves, which directs high pressure engine oil into the camshaft phaser cavity. The phaser cavity modifies the valve timing by rotating the camshaft in minued direction from its initial direction, which results in the camshaft timing being advanced or retarded.
The PCM regulates the camshaft timing depending on factors such as RPM and engine load. For twin cam or DOHC engines, VCT was used on either the intake or exhaust camshaft. Engines that have VCT on both camshafts are named as Ti-VCT. The use of variable camshaft timing on the exhaust camshaft is for improved emissions.
Vehicles with VCT on the exhaust camshaft do not require Exhaust Gas Recirculation (EGR) as retarding the exhaust cam timing achieves the same result.VCT on the intake camshaft is used mainly for increasing engine power and torque as the PCM is able to optimize the opening of the intake valves to match the engine conditions.
Ti-VCT (Twin Independent Variable Camshaft Timing (Ti-VCT)) : Twin Independent Variable Camshaft Timing (Ti-VCT) is the name given by Ford to engines with the ability to advance or retard the timing of both the intake and exhaust camshafts individually, unlike the original versions of VCT, which only operates on a single camshaft. This allows increased power and torque, especially at lower engine RPM, as well as increases fuel economy and reduces emissions. Ford Ti-VCT engines use BorgWarner’s Cam Torque Actuation which utilizes the technique “existing torsional energy in the valve train to rotate the camshaft”, instead the classical oil pressure driven cam phasing.
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