SparkRing Fix vibrations not working for calls, texts, and alerts on iPhone WHY SOME CARS USE TWIN SPARK IGNITION SYSTEMS Ever wondered why some engines have two spark plugs per cylinder instead of one? That's the magic of a twin spark ignition system, designed to Sound is a good example of frequency and vibration, but there is frequency and vibration without sound. There are a number of different belief systems around this, but bottom line is that