Variable Cam Timing
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Variable Camshaft Timing (VCT) is an
automobile A car or automobile is a motor vehicle with Wheel, wheels. Most definitions of ''cars'' say that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, pe ...
variable valve timing 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. It is increasingly being used in combination with varia ...
technology developed by
Ford Ford commonly refers to: * Ford Motor Company, an automobile manufacturer founded by Henry Ford * Ford (crossing), a shallow crossing on a river Ford may also refer to: Ford Motor Company * Henry Ford, founder of the Ford Motor Company * Ford F ...
. It allows for more optimum engine performance, reduced emissions, and increased
fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
compared to engines with fixed camshafts. It uses electronically controlled hydraulic valves that direct high pressure engine oil into the camshaft phaser cavity. These oil control solenoids are bolted into the cylinder heads towards the front of the engine near the camshaft phasers. 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. 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 PCM adjusts the camshaft timing depending on factors such as engine load and RPM.


History

For twin cam or DOHC engines, VCT was used on either the intake or exhaust camshaft. (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 In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust ...
(EGR) as retarding the exhaust cam timing achieves the same result. 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. VCT is used in Ford's
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5.4L 3-valve V8 engine, the Australian
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182 and 240
Inline-6 The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balan ...
s, and Ford's 4.6L 3-valve V8 engine used in the 2006-2010
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and 2005-2010
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. The 2.0L
Zetec Ford Motor Company used the Zetec name on a variety of inline 4-cylinder automobile engines. It was coined to replace "Zeta" on a range of 1.6 L to 2.0 L multi-valve engines introduced in 1991 because Ford was threatened with legal acti ...
Inline-4 A straight-four engine (also called an inline-four) is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft. The vast majority of automotive four-cylinder engines use a straight-four layout (with the ...
used in the 1998-2003 Ford Escort ZX2, Ford Contour, and 99-02 Mercury Cougar used VCT on the exhaust camshaft. The 2002-2004
SVT Focus The Ford Focus (first generation) is a compact car that was manufactured by Ford in Europe from 1998 to 2004 and by Ford in North America from 1999 to 2007. Ford began sales of the Focus to Europe in July 1998 and in North America during 1999 fo ...
( ST170 in Europe) also featured VCT, but on the intake camshaft of its modified version of the 2.0L
Zetec Ford Motor Company used the Zetec name on a variety of inline 4-cylinder automobile engines. It was coined to replace "Zeta" on a range of 1.6 L to 2.0 L multi-valve engines introduced in 1991 because Ford was threatened with legal acti ...
engine. In addition, the 1.7L
Zetec Ford Motor Company used the Zetec name on a variety of inline 4-cylinder automobile engines. It was coined to replace "Zeta" on a range of 1.6 L to 2.0 L multi-valve engines introduced in 1991 because Ford was threatened with legal acti ...
-S engine found in the European Ford Puma was equipped with variable camshaft timing. The 6.2L V8 introduced in the 2010 SVT Raptor also uses VCT. That motor has a single cam per bank, so it is dual-equal variable cam 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 independently, unlike the original versions of VCT, which only operated on a single camshaft. This allows for improved power and torque, particularly at lower engine RPM, as well as improved fuel economy and reduced emissions. 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. 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. Engines Using CTA System: * 5.0 Coyote Engines without CTA: * 3.7 Cyclone


See also

*
Variable Valve Timing 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. It is increasingly being used in combination with varia ...
*
Exhaust gas recirculation In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust ...


References

{{Reflist Variable valve timing Ford Motor Company