Honda Introduces its HYPER VTEC

a Directly Actuated Valve System for High-Output, Environment-Friendly 4-Stroke Engines

January 18, 1999, Japan


Tokyo, January 18, 1999 --- Honda Motor Co., Ltd. today announced the development of a new HYPER VTEC (Variable Valve Timing & Lift Electronic Control System) valve control system. Designed for 4-stroke motorcycle engines, this new system combines environment-friendliness and increased output at all engine speeds.
HYPER VTEC is the latest refinement of Honda's unique VTEC hydraulic valve control technology. Designed to improve 4-stroke engines; airflow and combustion efficiency, this new system is characterized by the camshafts directly actuating the valves via a lifter. The system not only allows for variation of the number of valves active depending on engine speed, but also provides for optimum lift amount and actuation timing of each valve thanks to specially designed camshaft profiles.

This system also provides the following advanced features;

  • Increasing output at all engine speeds
  • 6.6% improvement in fuel efficiency
    (from 34.7km/l to 37.0km/l at a constant 60km/h test on flat ground: Honda internal testing data)

At low to medium engine speeds, one intake valve and one exhaust valve out of four valves in each cylinder remain inactive, leaving only two active valves per cylinder. This helps increase intake air speed and generate a swirl effect within the combustion chamber for increased power output. Reduced friction losses also contribute to improvement in fuel efficiency.
At higher engine speeds, all four valves in each cylinder are activated to meet the increased gas flow requirements of higher revs.

This HYPER VTEC engine will first be used on the CB400 Super Four, a new sports bike to be released in the near future.



HYPER VTEC diagram
HYPER VTEC Operation
HYPER VTEC Operation
Valve Layout
Valve timing and cam profilr comparison
Output characteristics comparison