The Spark Plug Story

▶️ Visit to get a 30-day free trial 20% off your annual subscription The spark plug, a crucial component in gasoline internal combustion engines, has a rich history dating back to 1859 when Belgian engineer Jean Joseph Étienne Lenoir first used it in his coal gas and air engine. The design was refined by inventors like Nikola Tesla, Frederick Richard Simms, and Robert Bosch, with Bosch being the first to develop a commercially viable spark plug. Spark plugs ignite the air-fuel mixture in the engine’s combustion chamber by creating a spark between two electrodes separated by an insulator. The spark ionizes the gases in the gap, causing a rapid surge of electron flow that ignites the mixture, creating a controlled combustion event. Early spark plugs used mineral insulators and had short lifespans. The introduction of sintered alumina in the 1930s improved insulation, strength, and thermal properties, allowing higher voltages and better self-cleaning capabilities. In the 1970s, lead-free gasoline and stricter emissions regulations prompted further redesigns, including the use of copper core electrodes to improve self-cleaning and prevent pre-ignition. Multiple ground electrode plugs and surface-discharging spark plugs were explored in the following decades. The 1990s saw the introduction of coil-on-plug ignition systems and noble metal high-temperature electrodes, enabling higher voltages, stronger sparks, and longer service life. Modern spark plugs also incorporate ionic-sensing technology, which allows the engine control unit to detect detonation, misfires, and optimize fuel trim and ignition timing for each cylinder. This level of control has pushed engine designs to be more efficient and powerful. As electric vehicles become more prevalent, the spark plug’s evolution may soon reach its end, with electricity both pioneering the emergence and likely ushering in the end of the internal combustion engine. SUPPORT NEW MIND ON PATREON