Since automobiles were created, spark plugs have been essential for gasoline-driven engines because they help conduct electrical energy from the car’s ignition system to finalize its combustion process. Once the gas/air mixture is fully compressed within the cylinder head, the spark plug serves as a tiny bolt of lightning, which ignites the mixture, creating an explosion to push the piston downward.
Spark plugs aren’t necessary for diesel engines because they run with higher compression ratios that are sufficient enough to create the combustion without a spark. While up to 99 percent of all engines use one spark plug for each cylinder, many high-performance engines use two plugs for each cylinder.
Spark plugs usually have an inner electrode, which is covered by a porcelain insulated shell. This center electrode uses heavily insulated wires to connect to the output terminals of the ignition coil. The bottom of the spark plug has a threaded shell, which allows it to screw into the cylinder head; the bottom tip of the plug extends somewhat into the combustion chamber. The metal that’s used to coat the electrode is how the spark plug types are defined.
Sometimes called normal or standard spark plugs, copper plugs use nickel alloy coatings for the electrodes. The inner core is copper because copper is too soft a metal and would melt instantly if it was subjected to the extreme heat endured by the spark plug. Copper can conduct electricity well, which is why many manufacturers use it for the core.
They cost less and usually last less time, especially if they’re used on modern vehicles with a high-energy ignition system.
Sometimes, copper/nickel plugs are beneficial. Copper delivers a better spark for some conditions, such as those with high compression ratios and turbochargers. If your manual suggests using copper/nickel plugs, it is best to do so. However, most modern vehicles should not use copper/nickel spark plugs.
Single platinum spark plugs use a platinum center electrode. They’re more expensive because the element platinum is a rare material. Platinum spark plugs work well for normal driving conditions and can last longer. It’s a harder substance than nickel, ensuring that it doesn’t erode like copper/nickel. Therefore, the gap doesn’t widen when the metal wears away, preventing misfires on startup, reduced mileage, and a drop in power.
Sometimes, these platinum plugs are marketed as fine-wire centers, which has one or many platinum discs inside. Fine wire means that the inner center electrode is thinner, which means you don’t need to use as much of the premium metal.
Platinum spark plugs can resist carbon buildup effectively because they’re used at higher operating temperatures. They work well for modern engines that use a distributor-based electric ignition system.
Many times, the lifespan of platinum plugs is double that for copper, though some manufacturers claim you can change the spark plug at 100,000 miles because computers control the air/fuel mixture.
Single-platinum spark plugs use a platinum center electrode, but double-platinum spark plugs use the platinum plating for the center and ground electrodes. While this plug is more expensive, they also have better performance and a long life span.
Iridium spark plugs have better combustion and power, leading a smoothly running engine and longer life-span than other options.
Silver-tipped plugs have better thermal conductivity, but they aren’t as long-lasting as iridium or platinum. They’re usually recommended for older motorcycles and European performance cars.
Gapping means that the distance between the plug tip (where electricity comes) and the curved conducting electrode is adjusted as needed. You can do this by bending your electrode with a special tool.