Your engine inhales air and fuel, at the top of the compression stroke, the spark plug ignites the mixture. The spark plug only has that job, to ignite the mixture. Yep, you’ve got a whole ignition system for the sole purpose of one spark each cylinder at the top of every combustion stroke.
The spark plug is fitted to the cylinder head and depending on the plug type, can be made of different materials.
What is a spark plug made of?
The top of the spark plug is a terminal, which connects to the ignition coil and receives the current. This is then encased in an insulation to ensure the charge is contained and cannot arc. There is then a steel ring which conducts the charge from the terminal wire to a central electrode.
A copper/glass composite is responsible for insulating the center electrode and withstanding the heat of operation.
The charge then makes its way down to a thing called the u ground electrode which is separated from the tip of the center electrode by a miniscule measurement. This space is where the spark arcs and ignites the fuel and air.
It’s encased in a steel thread to screw into the cylinder head. Keeping it in place and sealing the combustion chamber.
How does a spark plug work?
Well based on what I’ve said above you get how the charge becomes the spark.
The ignition coil or distributor sends a charge to the spark plug. The spark plug transfers this down to the center electrode and arcs to the U ground. This arc combusted the fuel at the exact right time in the compression stroke.
The ECU or distributor decides when to send the spark and can advance or retard it as it likes. It chooses when it wants to blow things up, as long as it’s the best time to blow the thing up for maximum convenience.
What spark plug is best for my car?
Well generally, the one that your owners manual tells you to use. That’s the one that the engine has been designed to use.
There are a variety tips used in different spark plugs. You’ll often see platinum or iridium tips. There’s also a range of different ‘heats’. The different tips help prevent against wear during the spark cycles.
The different heats are based on application. A lower power engine will have a hotter spark plug, meaning less insulation and more heat escaping. A more high power engine needs a colder spark plug to ensure the heat doesn’t disrupt the exact park process.
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