What is the reason for the early opening and late closing of the engine intake valve?
2 Answers
The reasons for the early opening and late closing of the intake valve are as follows: The purpose of early opening the intake valve is to have a larger opening or a larger intake cross-sectional area at the beginning of the intake process, thereby reducing intake resistance and ensuring smooth intake. Early opening and late closing are intended to increase the intake time and thus the intake volume. Increased intake volume enhances engine power, while also reducing harmful substances produced after combustion of the air-fuel mixture, such as nitrogen oxides and carbon monoxide. This helps improve emission standards and reduce environmental pollution. Late closing of the intake valve: This is to fully utilize the inertia of the airflow, continuing the intake during the intake lag angle to increase the intake volume. Reduced intake resistance not only increases the intake volume but also decreases the power consumed during the intake process.
Having driven for decades, I've found that early opening and late closing of the intake valves are mainly designed to allow more air into the cylinders. When you start the engine, the piston begins to descend, and opening the intake valve early allows air to flow in ahead of time; closing it late means waiting until the piston is almost back up before shutting, utilizing the air's momentum to fill a bit more. This way, the engine breathes fully, delivering more power, especially at high speeds where it's both more forceful and fuel-efficient. Back when I drove the old Santana in my youth, if the valves weren't adjusted properly, it would feel sluggish, making long trips a struggle. Nowadays, cars come with computer-controlled adjustments, like VVT technology, which dynamically regulates this, ensuring smoother acceleration. If left unmaintained for too long, carbon buildup on the valves can render this function ineffective, leading to soaring fuel consumption and jerky starts, so it's essential to clean the intake system regularly. In short, this is all about improving efficiency, making the car feel more spirited, and extending the engine's lifespan.
