How Many Types of Spark Plugs Are There?
3 Answers
Spark plugs mainly come in the following types: standard spark plugs, extended insulator spark plugs, electrode spark plugs, seat spark plugs, polarity spark plugs, and surface gap spark plugs. Spark plugs are installed on the side or top of the engine. In early designs, spark plugs were connected to the distributor via ignition cables. Over the past decade, most car engines have transitioned to direct connection between ignition coils and spark plugs. Spark plugs mainly come in the following types: standard spark plugs, extended insulator spark plugs, electrode spark plugs, seat spark plugs, polarity spark plugs, and surface gap spark plugs. Working principle of spark plugs: The ground electrode of a spark plug is connected to the metal shell, which is in turn connected to the engine block via threads on the cylinder head. The insulator primarily serves to isolate the metal shell from the center electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. When current passes through the terminal nut and the center electrode, it ionizes the medium between the center electrode and the ground electrode, generating a spark that ignites the air-fuel mixture in the cylinder.
Spark plugs come in five common types, and I've replaced quite a few. Nickel alloy ones are the cheapest but have a short lifespan, needing replacement every 20,000 to 30,000 kilometers—older Santanas often use these. Single platinum plugs last longer, with a platinum-tipped center electrode, good for 50,000 to 60,000 kilometers, and many modern family cars come with these as standard. Double platinum plugs have platinum plating on both electrodes, providing more stable ignition, commonly used in cars like the Camry. Iridium spark plugs are the sharpest, with needle-fine electrodes for high ignition efficiency, though they're pricey—modified cars love them. There are also iridium-platinum hybrids, combining the benefits of both metals, ideal for turbocharged engines. When choosing, don’t just look at the material—match the heat range too. A wrong heat range can cause carbon buildup or knocking. It's best to buy according to the factory specifications.
I've been into car modifications for over a decade. Spark plugs are mainly categorized into three basic types based on electrode material: nickel alloy, platinum, and iridium. Nickel alloy plugs are low-cost but prone to erosion, making them most commonly used in taxis. Platinum plugs come in single and double variants. Single platinum plugs have platinum welded to the electrode tip, doubling their lifespan compared to nickel alloy. Double platinum plugs contain platinum in both the center and side electrodes, offering better conductivity. Iridium spark plugs can achieve an electrode diameter as small as 0.4mm, requiring lower ignition voltage, which is particularly beneficial for high-revving engines. Nowadays, there are also special racing models, such as those with fire-resistant coatings or quad-electrode designs. When choosing, remember to check the heat range rating – 6-7 is suitable for daily drivers, while 8 and above are for performance-oriented vehicles.
