Variable Valve Timing Systems

    Since valves are controlled by cams to change the valve timing the cams need to be changed.  By changing the cams, how far the valves move and how long they are opened can be changed.  

Automotive companies have developed systems to change the valve timing on their engines.  These systems range from simple systems that are used on engines in economy car to very elaborate and expensive systems used on world class automobiles.

   BMW Vanos System

This system changes the phase of the cams.  This allows the valves to stay open longer as the engine speeds increase.  This is a relatively simple system and has the least performance gains of VVT systems.

Honda  3 Stage VTEC

This system has three distinct stages and actually changes the cams that are operating th valves.  This system can change both timing and lift since it uses totally different cams for each stage. 

Toyota VVTL-i

This system combines the best of both of the other two systems described on this page. It changes the phase of the cams and changes the cams themselves. 

To find out more about other VVT system please go to the links page HERE.