When you want to boost your car’s performance and fuel efficiency, Variable Valve Timing (VVT) is a key technology to consider. It lets the engine tweak the timing of the intake and exhaust valves, which helps with power and fuel economy.
VVT started with early car innovations and has grown into advanced systems like Honda’s VTEC. But how does VVT actually work, and what’s the difference between continuous and discrete systems?
Knowing these details can help you understand the benefits and challenges of this technology.
History and Evolution
The history of Variable Valve Timing (VVT) technology started with the 1903 Cadillac Runabout, which was the first car to have adjustable valve timing.
VVT’s progress picked up in the 1920s with new patents, and in 1958, Porsche introduced an oscillating camshaft system.
In the 1960s, Fiat developed a VVT system using hydraulic pressure, and in 1989, Honda’s VTEC system significantly improved engine performance.
Types and Mechanisms
When looking into variable valve timing (VVT) systems, you’ll find a few different kinds, each with its own benefits and downsides.
Cam phasing changes the camshaft position to improve performance and save fuel.
Variable duration systems adjust how long the valves stay open and how high they lift, which boosts performance but can be more expensive.
Camless engines use advanced electronics for great flexibility.
Continuous variable valve timing fine-tunes the exhaust and intake valves to cut down on fuel use.
Continuous Vs. Discrete Systems
Many modern engines have either continuous or discrete variable valve timing (VVT) systems, each with their own features.
- Continuous Variable Valve Timing: Adjusts in real-time across all RPM ranges.
- Discrete Systems: Have fixed timing settings for specific RPM ranges.
- Engine Control Unit: Uses sensor data to make precise valve timing adjustments.
- Fuel Efficiency: Improved with late intake valve closing (LIVC) and early intake valve closing (EIVC).
- Emissions Control: Better with continuous systems.
Advantages and Challenges
Variable valve timing (VVT) can make your engine work better by adjusting power and fuel use at different speeds.
This can give you up to 7% better gas mileage, help reduce emissions, and make real-time changes as you drive.
But, VVT systems can be expensive and need regular upkeep, especially the oil control valves, which can make them less popular.