Is an ignition advance angle of 12 degrees or 9 degrees better?
2 Answers
An ignition advance angle of 9 degrees is better for the following reasons: The ignition advance angle is generally between 6 and 12 degrees. A 12-degree ignition advance angle is too large compared to 9 degrees, which can lead to delayed ignition. If ignition is delayed, the gas will have difficulty performing work, fuel consumption will increase, efficiency will decrease, and exhaust noise will become louder, affecting the engine's operational efficiency. Below is a related introduction to the ignition system: 1. Function: In a gasoline engine, when compression nears the top dead center, the combustible mixture is ignited by the spark plug, thereby burning and performing external work. For this reason, gasoline engine combustion chambers are equipped with spark plugs. The function of the ignition system is to generate a sufficiently energetic spark between the electrodes of the spark plug in the correct sequence according to the cylinder's working order. 2. Requirements: The voltage required to produce a spark when the spark plug electrodes break down is called the breakdown voltage. The secondary voltage generated by the ignition system must be higher than the breakdown voltage to ensure the spark plug fires. The magnitude of the breakdown voltage is influenced by many factors, including: (1) Spark plug electrode gap and shape: The larger the gap between the spark plug electrodes, the higher the breakdown voltage; electrodes with sharp edges require a lower breakdown voltage. (2) Pressure and temperature of the mixed gas in the cylinder: The higher the pressure and the lower the temperature of the mixed gas, the higher the breakdown voltage. (3) Temperature of the electrodes: The higher the temperature of the spark plug electrodes, the lower the gas density around the electrodes, resulting in a lower breakdown voltage.
I think whether 12 degrees or 9 degrees of ignition timing advance is better depends on the specific situation. When I adjusted my old car to 12 degrees, the acceleration was noticeably more aggressive, the throttle response was particularly crisp, and I felt much more confident when overtaking. However, I occasionally heard slight engine knocking when climbing hills with the AC on in summer, probably due to some detonation. Later, changing it to 9 degrees made the ride much smoother. Although the power was slightly weaker, the fuel efficiency improved significantly, allowing me to drive dozens of kilometers more on a full tank. Nowadays, most cars are equipped with knock sensors, and the ECU will automatically adjust the timing. So there's really no need to obsess over specific values in daily driving—what matters most is how smoothly the car drives. Also, it's safer to directly refer to the factory service manual's recommended settings.
