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As a crucial part of your gas-powered vehicle’s ignition system, spark plugs serve two maintenance purposes under the hood. Not only do spark plugs ignite the fuel-air mixture within an internal combustion engine, but they also relocate heat from the engine to the cooling system. The metal electrode on a spark plug is typically made of platinum, copper, or an iridium alloy. Are you wondering if there are drawbacks to using iridium spark plugs? Here’s what we know:

A brief history of spark plugs

A female service worker reconditioning spark plugs at a Navy Air Base
A female service worker reconditioning spark plugs | HUM Images/Universal Images Group via Getty Images

There doesn’t seem to be a definitive answer as to who exactly invented the very first spark plug. Still, most sources credit the creation to Belgian-born Jean Joseph Lenoir, who invented the internal combustion piston engine around 1860.

Some years earlier, a West African immigrant living in France also devised a spark plug, but like Lenoir, Edmond Berger never patented his invention, explains Napa Know How Blog.

In August 1898, Nikola Tesla was granted patent number US609250A for an electrical igniter. Still, it wasn’t until 1902 that Bosch engineer Gottlob Honold patented the high-voltage spark plug we recognize today. Similarly constructed spark plugs have been built into every gasoline-powered automobile engine since, says Automotive History.

How spark plugs work and what they’re made of

Comprised of a terminal connector, a hex head, a crush washer, a threaded bottom, a central electrode, and a ground electrode, a single spark plug sits at the top of each cylinder. To start the firing sequence, a piston draws in a mix of air and fuel as it travels down a cylinder.

When the piston moves back up, it compresses the air-fuel mixture. Just as the piston attains top dead center, or TDC, the central electrode provides an electric spark that arcs a small gap to the ground electrode to ignite the fuel and power the engine. Once the exhaust has been vented, the entire process repeats, explains HowStuffWorks.

Electrodes may be Y-shaped or notched and are made of metals that range from stainless steel to iridium to platinum. Considered the second-densest natural metal, iridium plugs are generally well-liked by drivers, but they have a few drawbacks, including a substantially higher cost. Extra care must also be taken during the installation of such spark plugs due to the brittle and combustible nature of iridium-coated electrodes.

The benefits of using iridium spark plugs

Switching out spark plugs is a necessary part of vehicle maintenance. Despite a tendency to crack if banged or scratched against another engine part, many drivers and mechanics greatly prefer iridium spark plugs.

Six times stronger than steel, iridium spark plugs can withstand much higher temperatures than their copper and platinum counterparts. Iridium spark plugs also offer cleaner ignition by completely combusting the air-fuel mixture during the starting sequence. It may not sound like much, but this sort of efficient ignition can result in noticeably improved fuel economy over time.

Drivers who need to accelerate to freeway speed in a hurry find that iridium spark plugs provide a noticeable difference, according to Jalopy Talk. Additionally, iridium spark plugs boost engine power and last much longer than plugs made with lesser metals.

Next time you switch spark plugs, consider shelling out a few more bucks for iridium, especially if you drive an off-road vehicle or do a lot of towing. Sure, they may cost three to four times as much as conventional plugs. Still, drivers who make the switch almost always say that iridium spark plugs pay for themselves with improved acceleration, fuel efficiency, and extended time between spark plug changes.


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