VTEC Function

• VTEC is a technology that is applied to many of Honda's performance overhead cam engines. In an overhead cam engine, a rotating camshaft or camshafts feature triangularly shaped lobes. These lobes open and close the cylinder head valves, which allow air and fuel to enter the engine cylinders, where it is combusted to produce engine power. Engines equipped with VTEC feature dual sets of cam lobes. At a designated point in the RPM range, the camshafts will switch to a larger set of lobes, which allow for an increased amount of air and fuel to enter the cylinders.
  
  

VCM Function

• Vehicle engines only utilize the bulk of their horsepower potential under heavy acceleration. When maintaining a steady highway speed, the vehicle does not require much horsepower. Honda's VCM technology takes advantage of this fact by deactivating a number of the engine cylinders in conditions where a high output of horsepower is not required. For example, a Honda V6 engine that is equipped with VCM will run on only three cylinders during steady cruising situations.
  
  

VTEC Benefits

• The smaller cam lobe profiles that a VTEC engine runs on during normal driving allow the engine to achieve maximum smoothness and fuel economy. However, small cam lobes limit an engine's performance potential in the high end of the rev range. By switching over to a larger set of cam lobes at the VTEC engagement point, the engine is able to take in a larger amount of air and fuel in the peak power segment of its RPM band. This optimizes the VTEC engine for both everyday and performance driving functions.
  
  

VCM Benefits

• Though the VCM function is entirely different from that of VTEC, the ultimate effect is the same. VCM allows Honda to achieve increased fuel economy out of engines that are still capable of producing high performance numbers. When all of the engine cylinders are activated, such as under full-throttle acceleration, the engine will produce its maximum amount of horsepower. However, when only a low amount of horsepower is required to maintain vehicle speed, a number of the engine cylinders cease to receive air and fuel injection. This optimizes the engine for both performance and economical driving.