Spark plugs are used to ignite the fuel mixture in the cylinders of an internal combustion engine. Even experienced motorists are confused by the great variety of spark plugs available on the market. Even the less experienced "generalists" sometimes get confused and have questions addressed to motor vehicle mechanics, electricians, and power system specialists.

In simple terms, a spark plug consists of a spark plug, an insulator, and two electrodes which are charged with between a thousand and a thousand volts, depending on many parameters.

The best spark plugs to buy right now

Champion Copper Plus 71 (under $5)

Champion Copper Plus 71 Spark Plug

This plug provides the quick and efficient start you need when switching on your lawn and garden equipment. Once in use, your outdoor power equipment will run smoothly without the misfires that can occur with old and worn spark plugs. New spark plugs can also improve fuel economy and reduce emissions.

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Bosch Automotive ZR6SII3320 (10Pk - under $100)

Bosch Automotive Double Iridium OE Replacement Spark Plug

Bosch plugs are designed for high performance and long service life, representing the best of OE spark plug technology. The ultra-thin wire construction and laser-welded tapered ground electrode ensure optimum performance, while the iridium centre electrode and ground electrode help it to overcome the distance.

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NGK 93911 (4Pk - under $30)

NGK Iridium IX Spark Plug

Designed specifically for the performance enthusiast, Iridium IX offers exceptional ignition performance, improved throttle response, and superior fouling protection. The finely ground 0.6mm laser-welded iridium tip offers high durability and a consistently stable spark, while the tapered ground electrode minimises the effect of electric extinction. A longer insulator nose prevents fouling, corrugated ribs on the insulator prevent flashover and the triple gasket seal eliminates flammable gas leakage.

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MSD 37194 (4Pk - under $30)

MSD 37194 Iridium Spark Plug

MSD spark plugs are designed to increase the efficiency of the combustion process and provide maximum power combined with increased durability. The centre plug tip is made from iridium to provide a better spark and increased stability. The patented ceramic material increases the dielectric strength of the plug body, forcing the spark, even at extreme cylinder pressures, to jump across the plug gap to the ground electrode.

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Vplus 8PCS Iridium Spark Plug (8Pk - under $50)

Vplus Iridium Spark Plug

Replacement racing spark plug used by many professional car drivers. Specifically designed with colder heat ranges than the factory plug to enable performance modifications and handle intense conditions.

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How to choose spark plugs

The spark plugs should be selected according to a number of parameters, depending on:

  • The type of ignition;
  • The type of power supply system (power steering, injection, mono or multi-point injection, etc.);
  • On the engine's degree of boost (compression ratio);
  • Engine operating conditions and fuels used (de-energized, boosted, supercharged, turbocharged, sports, etc.).

If the spark plug does not match the engine type, compression, and other parameters, the combustion mixture will ignite automatically and may lead to an increase in engine speed, up to complete destruction of the engine.