Most modern engines will come equipped with Variable Valve Timing (VVT). VVT technology produces a performance and efficiency increase, but how does it really work?
Whether you are simply interested in how VVT works or are looking to learn about the benefits when car shopping, read on for an overview of the essential benefits variable valve timing delivers to today’s modern engines.
What is Variable Valve Timing?
Regardless of which variable valve timing assemblies are used, they all accomplish the same thing: they vary valve timing.
The technology is common among most manufacturers, but many make slight variations to the process, usually with a different name.
For example, Toyota simply calls theirs VVT-i (Variable Valve Timing with Intelligence), Honda calls theirs VTEC (Variable Valve Timing and Lift Electronic Control), and Ford uses the name VCT (Variable Camshaft Timing). BMW, Nissan, and many manufacturers have various forms of variable valve timing.
The technology uses complicated mechanical and hydraulic actions inside the engine. It works by allowing the engine to deliver increased performance when requested by the driver, but also has increased fuel efficiency when performance isn’t really needed.
Here are the three ways that an engine’s valve timing is commonly varied:
- The intake or exhaust valve timing may be sped up or slowed down, depending on the need at the time.
- Two sets of cam lobes per valve are utilized. In this case, a sliding locking pin determines which lobe will operate the valve.
- Timing and lift are constantly varied for maximum performance and efficiency.
VVT Engine Advantages
#1. High RPM Power.
When you press on the accelerator, the car’s computer activates an electric switch for the oil control solenoid to initiate the switch over to a more aggressive camshaft profile with hydraulics. This provides the driver a lot more high-end performance. Most drivers can even hear or feel the engine switch. It’s that noticeable.
Not all variable valve timing engines are performance driven. Plenty of manufacturers use the technology to gain fuel economy in an engine, with no consideration given to some level of performance.
#2. Low RPM Efficiency.
When you are driving at the lower end of the RPM range, the variable valve timing system is using a camshaft profile that is designed to provide a smoother idle and better fuel economy, and more low-end power and torque.
This allows the driver to do two things: drive the car better with more drivability and do it without giving up efficiency.
#3. Electric Monitoring.
The computer is also monitoring engine RPM in real time, throttle position and a host of different conditions. When the computer decides you are demanding more from the engine, it will switch to a different camshaft profile that gives you more power and torque.
#4. Lower Emissions.
Another benefit of the variable valve timing system is increased internal gas recirculation. More gas recirculation means more direction for the gases, which can also decrease emissions.
This is significantly important for manufacturers who are working to get their vehicles under a specific limit for exhaust gasses.
Final Thoughts
VVT increases power at high revs, but it’s the low-down torque that makes it so usable; it’s better for regular driving, not just because of the additional power, however.
In addition, VVT makes these engines much more fuel efficient than any non-VVT engine thanks to greater precision for the handling of engine valves.
There’s going to be pros and cons of the system, but quite simply, the benefits of VVT far outweigh things like complexity and cost of production.