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The cams open ( lift) the valves for a certain amount of time ( duration) during each intake and exhaust cycle. Piston engines normally use valves which are driven by camshafts.

An engine equipped with a variable valve timing actuation system is freed from this constraint, allowing performance to be improved over the engine operating range. Without variable valve timing or variable valve lift, the valve timing is the same for all engine speeds and conditions, therefore compromises are necessary. The timing, duration and lift of these valve events has a significant impact on engine performance. The valves within an internal combustion engine are used to control the flow of the intake and exhaust gases into and out of the combustion chamber. Two-stroke engines use a power valve system to get similar results to VVT. Increasingly strict emissions regulations are causing many automotive manufacturers to use VVT systems. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems. It is increasingly being used in combination with variable valve lift systems. In internal combustion engines, variable valve timing ( VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. This engine uses continuously variable timing for the inlet valves Many new Ford engines feature Ti-VCT, including ones used in the 2011-2015 Mustang, 2011 Edge and Edge Sport, 2011 Lincoln MKX, 2011 Fiesta, 2011 Explorer, 2011-2016 F-150, and 2012 Focus.Cylinder head of Honda K20Z3. Some Ford Ti-VCT engines use BorgWarner's Cam Torque Actuation (CTA) which utilizes the "existing torsional energy in the valve train to rotate the camshaft" instead of traditional oil pressure driven cam phasing. This allows for improved power and torque, particularly at lower engine RPM, as well as improved fuel economy and reduced emissions. 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 independently, unlike the original versions of VCT, which only operated on a single camshaft. That motor has a single cam per bank, so it is dual-equal variable cam timing. The 6.2L V8 introduced in the 2010 SVT Raptor also uses VCT. In addition, the 1.7L Zetec-S engine found in the European Ford Puma was equipped with variable camshaft timing. The 2002-2004 SVT Focus ( ST170 in Europe) also featured VCT, but on the intake camshaft of its modified version of the 2.0L Zetec engine. The 2.0L Zetec Inline-4 used in the 1998-2003 Ford Escort ZX2, Ford Contour, and 99-02 Mercury Cougar used VCT on the exhaust camshaft. VCT is used in Ford's Triton 5.4L 3-valve V8 engine, the Australian Barra 182 and 240 Inline-6s, and Ford's 4.6L 3-valve V8 engine used in the 2006-2010 Ford Explorer and 2005-2010 Ford Mustang GT. VCT on the intake camshaft is used primarily for increasing engine power and torque as the PCM is able to optimize the opening of the intake valves to match the engine conditions. (Engines that have VCT on both camshafts are now designated as Ti-VCT.↓) The use of variable camshaft timing on the exhaust camshaft is for improved emissions, and vehicles with VCT on the exhaust camshaft do not require exhaust gas recirculation (EGR) as retarding the exhaust cam timing achieves the same result. The PCM adjusts the camshaft timing depending on factors such as engine load and RPM.įor twin cam or DOHC engines, VCT was used on either the intake or exhaust camshaft. The phaser cavity changes the valve timing by rotating the camshaft slightly from its initial orientation, which results in the camshaft timing being advanced or retarded. The powertrain control module (PCM) transmits a signal to the solenoids to move a 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 of the engine near the camshaft phasers. It uses electronically controlled hydraulic valves that direct high pressure engine oil into the camshaft phaser cavity.

It allows for more optimum engine performance, reduced emissions, and increased fuel efficiency compared to engines with fixed camshafts. Variable Camshaft Timing ( VCT) is an automobile variable valve timing technology developed by Ford. RH side VCT Oil Control Solenoid and harness from a Ford 4.6L SOHC 3V V8 engine