How to choose the best spark plug for your car?

Sparking a start

Found in any gas-fueled combustion engine, a spark plug is a component that screws into the engine’s cylinder head. Spark plugs have high voltage electricity sent to one end and ignite a spark at the other end. The spark fires the air and fuel mixture within the engine and creates the combustion that powers your car. Without spark plugs, your car will not start.

 

What are the different materials that spark plugs are made of?

The majority of spark plugs feature a copper-core center electrode. Copper is an excellent conductor of electricity – better than any other type of material used in spark plugs – and also transfers heat faster. However, copper is soft and has a low melting point so it is always covered with a nickel alloy to protect it. Depending on the plug type, it can have a platinum or iridium tip on the electrodes to optimize performance.

What is the purpose of metal in a spark plug?

Manufacturers use precious and other metals in the center and side electrodes of a spark plug. The metal channels the high voltage from the spark plug wire through the spark plug so it can spark when it goes across the small gap between the central electrode and the side electrode. This is the vital spark that starts the combustion process.

The use of metals like nickel alloy, platinum and iridium reduces the wear caused by high voltage sparks. These metals also help extend the interval between spark plug changes and decrease the misfire rate.

 

What are the advantages and disadvantages of the copper spark plug?

The copper spark plug is the most common and cheapest plug available. While almost all spark plugs feature a copper core, many people refer to the common spark plug as a “copper” spark plug. A standard spark plug typically features a nickel-alloy outer material fused to the copper-core electrodes.

Copper spark plugs run cooler and provide more power in performance driving situations. They are often installed as original equipment in turbocharged engines and engines with higher compression ratios. Copper spark plugs are also often used in older (pre-1980s) vehicles with a distributor-based ignition system.

The nickel-alloy outer material used in the copper spark plug isn’t as hard as other metals so it wears down more quickly with the high pressure and heat created in the cylinder of the engine. Over time, this wear leads to the spark plugs fouling and not working as efficiently as they did when they were new. Due to this short lifespan, most copper spark plugs need to be changed every 20,000 miles.
 

 

What is the scoop on platinum spark plugs?

Platinum is much harder metal than nickel alloy and has a higher melting point. Since platinum is harder, it holds its sharp edge much longer than a conventional spark plug, up to 100,000 miles. Longevity is a key advantage of platinum spark plugs.

Another advantage of platinum spark plugs is that they run a little hotter, which burns deposits off the spark plug better and helps prevent fouling. Platinum also handles high heat, enabling the spark plug to wear better.

Platinum spark plugs come in two varieties - single and double platinum. A single platinum plug is much like a copper spark plug with a platinum disc welded to the center electrode; a double platinum spark plug has a platinum disc on both the center and side electrodes.

 

What about iridium spark plugs?

Iridium is said to be six times harder and eight times stronger than platinum with a 700° higher melting point. Iridium spark plugs have extremely fine electrodes while retaining excellent wear characteristics. Thanks to its strength, iridium spark plugs can last up to 25% longer than comparable platinum spark plugs.

Iridium spark plugs feature a fine wire center electrode that is designed to conduct electrical energy better and increase firing efficiency.

There is a price for this precious metal. Iridium spark plugs are typically the most expensive, ranging from $8 to $15 each.

 

How do I select the best spark plug material for my vehicle?

To find out the recommended spark plugs for your specific vehicle, check your owner’s manual. If your owner’s manual specifies iridium spark plugs, don’t downgrade to platinum spark plugs or copper spark plugs; if you downgrade, you run the risk of poor engine performance. You can also consult your mechanic for guidance on selecting the best spark plug for your car.