Continually at the forefront of automotive technology, Honda has been leading engine development due in large part to an intense passion for the core product. And it is same passion, coupled with a challenging spirit that makes Honda engines different from any other. So it comes as no surprise that with growing interest in global environmental protection, Honda continues to research in the development of environment-friendly motors. But improving fuel consumption, cleaning exhaust and reducing engine noise while maintaining a powerful output is a very difficult technical problem.

Honda’s answer to this challenge is the Hyper VTEC engine, featuring a direct-actuated type valve control system that reconciles engine output with environmental protection measures. During the early stages of its development, key objective were first identified. One of which included guaranteeing a kinetic valve system performance that equalled high revolution engines of over 10000rpm, while ensuring a minimal increase in mass around the valve. Simply put, the Hyper VTEC motor had to be compact, efficient, reliable and required only minimum resources to produce. With these goals in place, coupled with Honda’s experience in developing the REV engine for the Japan-market CBR400F motorcycle in 1983, it paved the way for the birth of the Hyper VTEC.

Unlike other systems, the Hyper VTEC system is unique and designed specifically for four-valve engines, consisting of a cylinder equipped with two intakes valve and two exhaust valves. Normal valves work over the whole range from low-speed to high speed revolutions, and special shutdown valves in the low and medium revolution ranges and are only activated during high revolution operation. In addition to the valves are hydraulic control system that includes the valve operation switchover system and a hydraulic circuit that is built inside the valve lifter of paused valves. Valve shutdown and actuation are controlled by the positions of the valve switchover pins-known as slide pins-built inside the valve lifters, with cam profiles for optimum valve timing set on individual normal and shutdown valves.

When the valves are in shutdown, no hydraulic pressure works on the slide pins and so the slide pins are pushed against the stopper pins by return springs. In this state, as the valve stems occupy holes found in the slide pins, the valves remains in shutdown even if the cams continue to drive the valve lifters and switchover mechanism. The valve lifters and switchover mechanism then follow the motion of the cam profiles with outer valve springs. The scenario changes once a preset engine speed is reached. The spool valve begins buy allowing hydraulic pressure to pass through the cylinder head, which in turn pushes the slide pins through the outer peripheral orifices of the valve lifter. Since sliding of the slide pins takes place when valve lifters are driven, the flat section of the slide pins pushes the valve stems to move both the valves and valve lifters as a single unit. Valves, valve retainers and cotters then follow with the motion of cam profile using inner springs.

A comparison of Hyper VTEC engines and base engines using a conventional valve mechanism shows that a measureable power improvement is seen in medium and low speed ranges. When an intake and exhaust are further introduced, improvements in high-speed range are also achieved. Most noticeably, ease of handling and positive acceleration is obtained by a change in torque characteristics at the moment of switchover from two to four valves. Other improvement seen in the Hyper VTEC system are a reduction in operational friction and accompanying engine heat, improved fuel consumption, a reduction in operating noise – a full 2 to 5dB less than conventional engines – and an overall improvement in response.

 But perhaps the best way to appreciate the numerous benefits of the Hyper VTEC is to experience it firsthand. And you can, only with the new Honda CB400 Super Four sports bike, where the Hyper VTEC is scheduled to make its debut. Riding just got a boost in hyper fun!