Spark plug gap
Spark plug this small part also has a very important parameter - clearance. This gap refers to the distance between the spark plug center electrode and the ground electrode. It is because of this gap that spark plugs have a "service life".
In the above, we have known that spark plugs will have different service life due to different electrode materials. This is mainly because the spark plug slightly consumes the precious metal on both electrodes with each discharge. Over time, as the electrode is used for a longer period of time, there will be less precious metal on the electrode, then the distance between the center electrode and the ground electrode will become larger, and this gap is called the spark plug gap.
Typically, spark plug gaps start at 0.6mm and increase in units of 0.1mm to 1.1mm, then 1.5mm and 2mm. For our ordinary family car, the spark plug gap is basically between 0.8mm and 1.1mm.
A larger gap requires more voltage from the ignition coil to produce a spark. The benefit is that the larger the gap, the faster the spark speed, which allows the gas mixture in the cylinder to burn more fully, resulting in lower exhaust particulate emissions.
However, a bigger spark plug gap is not always better. The larger the gap, of course, requires more voltage from the ignition coil to produce a spark. Although the original factory ignition coil will leave a redundancy when leaving the factory. But if the gap is too large and the voltage exceeds the redundancy, the power from the ignition coil is not enough to ignite the spark plug's mixture of oil and gas, eventually causing the engine to catch fire and the vehicle to lose power.
However, if the electrode material is good enough, the ignition coil voltage should not be considered too much when designing the gap. The iridium and ruthenium-gold spark plugs allow a larger spark gap without changing the spark coil voltage. Crucially, the current NGK's ruthenium-gold spark plug defaults to a 1.5mm spark plug gap. That is, as long as the material is good enough, a bigger spark plug gap is not a problem.
