Variable valve timing (VVT) improves engine performance by changing when the intake and exhaust valves open and close according to engine speed and load.
At low engine speeds, the system can adjust valve timing to improve combustion efficiency, idle quality, and low-speed torque. At higher RPM, it can change the timing to keep the valves open longer or optimize valve overlap, allowing the engine to breathe more efficiently and produce more power.
The main benefits are:
- Better low-end torque: Optimized valve timing improves cylinder filling at lower RPM.
- More high-RPM power: The valves can be timed to improve airflow when the engine is spinning quickly.
- Improved fuel economy: The engine can reduce pumping losses and operate more efficiently under light loads.
- Lower emissions: More precise control of combustion and exhaust gases can reduce certain emissions.
- Broader powerband: Instead of being optimized for only one RPM range, the engine can perform efficiently across a wider range.
More advanced systems can also vary valve lift in addition to timing, giving the engine even greater control over airflow.
In simple terms, VVT allows an engine to change its breathing characteristics as operating conditions change, giving a better balance of power, efficiency, drivability, and emissions than fixed valve timing.
