iVTEC

i-VTEC, sometimes written as iVTEC, is Honda's intelligent variable valve timing and lift electronic control system. It builds on the broader VTEC concept by integrating valve-lift switching with electronic control of cam timing, allowing the engine to adapt valve operation across a wide RPM range to improve power, torque, and efficiency.

How it works: The system uses the ECU to manage hydraulic actuators on the camshafts. At low RPM, a single, low-lift profile provides smooth running and efficiency; as RPM rises, the system switches to a higher-lift cam profile and may adjust intake cam timing to optimize airflow. In many implementations, i-VTEC combines VTEC lift switching with variable intake timing (and sometimes exhaust timing) to broaden the effective cam-swap window.

History and applications: i-VTEC was introduced by Honda in the late 1990s and has since been used across many engines in Honda and Acura vehicles, including inline-four and V6 powerplants. It is marketed to deliver a balance of fuel efficiency and performance, with some models emphasizing economy while others emphasize high-end power.

Maintenance and reliability: The system depends on engine oil quality and pressure; common failure modes involve hydraulic units, solenoids, or cam phasers. Regular oil changes with the manufacturer's recommended grade help preserve operation. Repair typically involves servicing or replacing the affected hydraulic components.

See also: VTEC, variable valve timing, Honda engine technology.