What is the method to distinguish between the lengths of Nissan's intake and exhaust valves?
2 Answers
Nissan's method to distinguish between the lengths of intake and exhaust valves is that the exhaust valve has a long spring, while the intake valve has a short spring. Introduction to intake and exhaust valves: The function of the exhaust valve is to expel the burned exhaust gases and dissipate heat, while the intake valve's role is to draw air into the engine to mix with fuel for combustion. Introduction to valves: Valves are specifically responsible for introducing fuel into the engine and expelling exhaust gases. Traditional engines have only one intake valve and one exhaust valve per cylinder. This design is relatively simple, cost-effective, easy to maintain, and performs well at low speeds. However, its drawback is that it is difficult to increase power, especially at high speeds, where the charging efficiency is low and performance is weaker. To improve intake and exhaust efficiency, multi-valve technology is now commonly used. A typical configuration is four valves per cylinder, meaning a four-cylinder engine would have a total of 16 valves. The notation "16V" often seen in automotive data indicates that the engine has 16 valves. This multi-valve structure facilitates the formation of a compact combustion chamber, with the fuel injector positioned in the center, allowing for quicker and more uniform combustion of the air-fuel mixture. The weight and lift of each valve are appropriately reduced, enabling faster opening and closing speeds.
I often tinker with Nissan engines, and distinguishing between the lengths of intake and exhaust valves is actually quite interesting. Generally, the intake valve is slightly longer than the exhaust valve to allow air to flow in more smoothly, and it's positioned closer to the cylinder's intake port side. The exhaust valve, on the other hand, is shorter but sturdier because it has to withstand high-temperature exhaust gases, and the material is more heat-resistant. To differentiate them, you need to use calipers or a ruler to measure the length directly after removing the cylinder head. In Nissan engines like those in the Qashqai or Altima, the difference is very small, only a few millimeters, so you can't rely on visual inspection alone. The position can also help distinguish them—the intake valve is always on the airflow inlet side, while the exhaust valve is near the outlet. Remember, don't mix them up, as it can cause unstable idling or high fuel consumption. Be careful during maintenance, keep everything clean, and avoid damaging the parts.
