Automotive technology has advanced so much that one may argue the standard spark plug has disappeared altogether and all plugs are performance enhanced. The truth is that standard plugs, much like the spark plugs your dad and grandfather used, are around and perform perfectly well. Older model and antique, classic and collectible cars need little in the way of performance spark plugs.
All spark plugs have a threaded metal hex shell to seal the combustion chamber of the cylinder. Plugs also have an insulator and electrodes. The shell is zinc-plated to extend the life of the spark plug. The insulator keeps the ignition voltage grounded across the combustion chamber gap. The insulator also moves the heat from the combustion to the engine’s cooling system. The electrodes make the spark that ignites the air/fuel mixture inside the cylinder. The insulators are made of ceramic. Modern vehicles use either a gasket to sit flat against the machined surface in the cylinder head or a taper-type seal that sits against an angled seat in the head.
A common spark plug features a chromium nickel alloy that reduces corrosion. Nickel-alloy plugs typically have a copper core center electrode. While the most basic spark plug may have a melting point at 1,760 degrees Fahrenheit, the nickel-alloy version has a 2,647-degree melting point. Conventional plugs begin to have problems igniting air/fuel mixture ratios of 15 to 1 while nickel-alloy plugs can ignite leaner mixtures with a 17 to 1 ratio.
The platinum spark plug is the low end of the performance plug range. However, there is considerable debate whether platinum plugs make much of a difference in engine performance, particularly in emissions and fuel efficiency. For the average driver who thinks of his vehicle as nothing more than transportation, the difference between a standard plug and a platinum one probably is negligible. Consider, though, that the standard spark plug has a melting point at 1,760 degrees Fahrenheit while a platinum plug has a 3,216-degree melting point. The platinum plug, with a platinum center electrode, has a strong resistance to corrosion and can withstand a harsh environment. The platinum plug should improve fuel economy, give the vehicle a faster start and maintain peak spark performance for more than 60,000 miles.
Iridium is a top-end performance spark plug made with an extremely hard precious metal. Spark plug makers use laser technology to weld an iridium tip to the plug. This provides better, more efficient spark for fuel economy. Iridium plugs feature a center electrode with a much smaller diameter than conventional plugs, giving it a more concentrated spark, but about 5,000 volts less than the standard plug. This puts less strain on the ignition system and enhances the vehicle’s throttle response. Its melting point is high at 4,449 degrees Fahrenheit, which is eight times more than platinum plugs.
