VANOS

Not to be confused withVanosorVanossGaming.

VANOS units on the intake and exhaust camshafts of aBMW N52engine

VANOSis avariable valve timingsystem used byBMWon various automotivepetrol enginessince 1992. The name is an abbreviation of the German words forvariable camshaft timing(German:variable Nockenwellensteuerung).

The initial version (retrospectively renamed "single VANOS" ) was solely used on the intake camshaft, while the later "double VANOS" systems are used on intake and exhaust camshafts. Since 2001, VANOS is often used in conjunction with theValvetronicvariable valve lift system.

Operation

VANOS is avariatorsystem that varies the timing of thevalvesby moving the position and thecamshaftsin relation to the drive gear. The relative timing between inlet and exhaust valves is changed.

At lower engine speeds, the position of the camshaft is moved so the valves are opened later, as this improves idling quality and smooth power development. As the engine speed increases, the valves are opened earlier: this enhances torque, reduces fuel consumption and lowers emissions. At high engine speeds, the valves are opened later again, because this allows full power delivery.

Single VANOS

The first-generationsingle VANOSsystem adjusts the timing of the intake camshaft to one of two positions — e.g. the camshaft is advanced at certainengine speeds. VANOS was first introduced in 1992 on theBMW M50engine used in 3 and 5 Series. In 1998 single infinitely variable VANOS was introduced on theBMW M62V8 engine.

Double VANOS

The second-generationdouble VANOSsystem adjusts the timing of the intake and exhaust camshafts with continuously variable adjustment, based on engine speed and throttle opening. The first double VANOS system appeared on theS50B32engine in 1996.

See also

• Valvetronic– BMW's variable valve lift system