Spark Plugs 101-All You Need To Know

Spark Plugs 101-All You Need To Know

Spark Plugs 101-All You Need To Know

All you need to know about Spark Plugs will be explained in this graphic post.

A Spark Plug

Spark plugs are necessary for a petrol internal combustion engine, to start generating its power. Here you will learn all there is to know, about Spark Plugs.

Spark Plugs have 2 primary functions

  • To ignite the petrol/air mixture in a car’s combustion chamber.
  • To dissipate heat from the combustion chamber, this is based on the length of the insulator nose and the materials used for the centre electrode and the insulator.

Spark Plug Operation

Let’s get technical.

A high voltage Ignition Coil supplies the Spark Plug with voltage.

As the voltage flows from the Ignition Coil, a voltage difference between the plug’s centre electrode and its side electrodes develop.

No current can flow as the petrol/air mixture act as an insulator in the Spark Plug’s gap.

As the voltage gets higher it changes the structure of the gases between the electrodes.

Once the voltage exceeds the dielectric strength of the gases, the volatile compressed petrol/air mixture can now be ignited by the rising voltage which ideally reaches highs of between 55,000 and 65,000 volts DC.

Spark Plugs usually require voltage in excess of 20,000 volts DC to fire properly, hence (55,000/65,000 Volts DC) This high voltage enables the Spark Plug Gap to be breached.

The ignition of the highly volatile petrol/air mixture causes an explosion inside the car’s combustion chamber.

The expanding gases, as a result, forces the car’s pistons in a downward motion, converting reciprocating motion into rotary motion to drive the car’s wheels via a transmission and drivetrain.

+++<  Such a small spark creating such great motion, the wonders of technology.  >+++

Learn More About Spark Plugs 

 Basic Spark Plugs

The 1st reliable Spark Plug was invented in 1903 by Oliver Lodge.

Modern cars today use a basic Spark Plug with a Copper core surrounded by Porcelain for insulation and heat dissipation, Metal Nickel Alloy encases the Porcelain as protection, this is considered a standard Spark Plug.

A 3 cylinder engine uses 3 Spark Plugs, a 4 cylinder engine, 4 Spark Plugs and so on, but a Hemi engine uses 2 Spark Plugs per cylinder, there are many other derivatives out there but is inconsequential to this post.

As there are different car engines, there are also different Spark Plug types.

spark plug parts
A Cutaway View of a Modern Spark Plug

Spark Plug Heat Ranges.

Heat ranges of spark plugs
Spark Plug Heat Ranges Explained

High heat range plugs are used in less powerful, Non Performance, Standard Engine types.

Cold plugs are used in High-Performance Engines, the heat range classification is basically the ability of the Spark Plug to dissipate heat from the combustion chamber to the cooling system.

This is extremely important as the use of the wrong heat range Spark Plug being used can cause serious damage to a High-Performance Engine. 

Rule of Thumb

  • High heat range – Less ability to dissipate heat from the combustion chamber.
  • Low heat range, – More ability to dissipate heat from the combustion chamber.

How to fit Spark Plugs

 Determining Engine Faults just by looking at how Spark Plugs burn.

This is possible as the chart shows.

burn chart
Spark Plug Burn Chart


Advanced, Performance Spark Plugs

Iridium Plug

More advanced or should we say, expensive Spark Plugs use different, more expensive metals in its central core, such as Platinum and Iridium.

These metals have a higher melting point which means it can operate in more advanced engine types, such as racing car engines which produce higher operating temperatures.

So in closing, there is an array of Spark Plug types and brands out there, in finding the correct application for your car’s engine,

I would suggest you simply consult your car’s owner’s manual for the correct Spark Plug application.

Failing that, your local Auto Part Store will be able to help, as they are generally well versed and have Spark Plug Charts to identify the correct Spark Plug type for your car.

Owner's Manual
Owner’s Manual for a Toyota Yaris T3

I trust that this post was helpful and enlightening as it was intended to be


 ==<  I welcome feedback of any kind, in learning how you, my visitors feel  >==

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Until Next Time “Safe Motoring”

Gary De La Cruz

I have been 30+ years in the motor industry, still hands on, and have great passion for my chosen profession, I learn new things each day and believe that "if you enjoy your work, you never have to work a day in your life"I believe in honesty, integrity and helping where help is needed.

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