BMW's equivalent to Honda's VTEC variable valve timing system is called VANOS.
Understanding BMW's VANOS System
VANOS is BMW's innovative variable valve timing system, designed to optimize engine performance, enhance fuel efficiency, and reduce emissions across various operating conditions. This system has been a cornerstone of BMW's petrol engines since its introduction in 1992.
The name VANOS itself is an abbreviation derived from the German phrase variable Nockenwellensteuerung, which translates to "variable camshaft timing."
How VANOS Operates
At its core, VANOS works by adjusting the angular position of the camshafts relative to the crankshaft. This precise adjustment alters the valve overlap and lift, allowing the engine to adapt its breathing characteristics to different engine speeds and loads.
Key operational aspects include:
- Improved Torque: By retarding or advancing intake (and sometimes exhaust) valve timing, VANOS can increase torque output, particularly in the lower and mid-range RPMs, where it's most frequently needed for daily driving.
- Enhanced Fuel Efficiency: Optimizing valve timing ensures that the engine combusts fuel more completely and efficiently, leading to better mileage.
- Reduced Emissions: Precise control over valve timing helps to minimize unburnt hydrocarbons and noxious gases by facilitating more efficient combustion and internal exhaust gas recirculation.
- Smoother Idle: At low engine speeds, VANOS can ensure a more stable and smoother idle by adjusting valve timing for optimal air-fuel mixture.
Types of VANOS
Over the years, BMW has evolved its VANOS technology:
- Single VANOS: Early iterations, primarily adjusting the intake camshaft timing.
- Double VANOS (or Dual VANOS): More advanced systems that independently adjust both the intake and exhaust camshafts. This provides a much broader range of control over valve timing, leading to greater improvements across the entire engine speed range for power, efficiency, and emissions.
VANOS is a crucial technology that allows BMW engines to deliver their characteristic blend of power, refinement, and efficiency.
