Spark Plugs

Q: What does a spark plug do?

A spark plug’s basic function is to ignite the air-fuel mixture within the combustion chamber of a petrol engine. Spark plugs provide a path for electrical energy from the ignition coil to generate a spark needed for this air-fuel mixture. The quality of the ignition spark directly affects several factors for both the quality of the driving experience and the environment. These include starting, smooth running, general engine performance and efficiency as well as the reduction of harmful emissions.

Q: What are the symptoms of bad spark plugs?

Symptoms of bad spark plugs include reduced fuel economy, rough idling, engine misfiring and difficulty starting the engine.

Q: Why do spark plugs fail?

There are a variety of reasons why spark plugs fail. These include: old age (recommended replacement interval has been ignored), carbon build up, overheating, oil present in the combustion chamber and the incorrect spark gap.

Q: What metal is used in spark plugs?

A variety of different metals can be used in spark plugs. Almost all spark plugs feature a copper cored inner central electrode because copper is an excellent electrical conductor. Copper, however, is a very soft metal with low resistance which means that it is not suitable as an outer centre or ground electrode. NGK SPARK PLUG’s standard range of plugs feature a nickel alloy outer centre electrode (fused to an inner copper core) and a nickel ground (side) electrode. The company’s premium range features extremely hard metals like iridium and platinum which guarantee longer replacement intervals.

Q: How often do you need to change spark plugs?

This depends on a range of conditions such as the engine’s condition, if the plugs were correctly installed, the type of metal present on the plug’s outer centre and ground electrodes etc. Generally, the driver or rider should refer to the maintenance intervals recommended by the manufacturer. In this context standard nickel spark plugs need to be replaced earlier than precious metal spark plug types that are more resistant with regards to wear.

Q: Is spark plug torque necessary?

It is absolutely necessary to tighten a spark plug to the specified turning angle or torque setting. If the torque is set too low, there is a risk of compression loss. Additionally, the insulator and electrodes may also be damaged as a result of excessive vibrations. If the torque is set too high, however, the metal shell of the spark plug will be over-stressed, increasing the likelihood of it yielding or expanding. Expansion can cause the heat dissipation zones to be disrupted. Overheating, melting of the electrodes and even engine damage are other potential outcomes.

Q: What causes carbon fouling on spark plugs?

Common reasons for this include the wrong spark plug heat range, a non-optimal engine combustion process and poor running conditions like continuous low-speed driving and short trips. A spark plug must reach a temperature of 450°C before it starts to self-clean by burning off carbon deposits. Regular short trips and continuous low-speed driving, however, result in the spark plug being unable to reach this critical temperature, making conditions for fouling ripe.

Q: When should you use colder spark plugs? Do hotter spark plugs make a difference?

This depends on the type of engine being used. Low power engines such as lawnmowers and chainsaws don’t produce large amounts of heat, meaning that a ‘hot’ spark plug (with a low heat range) is needed to reach optimum performance temperature. High-performance engines, however, generate a large amount of heat, resulting in the requirement for a ‘cold’ spark plug (with a high heat range). The heat range number, which typically varies between 5-10, is featured within a spark plug’s code (found on the ceramic insulator). This number illustrates how ‘hot’ or ‘cold’ the particular plug in question is. The lower the number (e.g., 5 or 6), the hotter a spark plug is, whereas the higher the number (e.g., 9 or 10), the colder the spark plug is.

Q: Are all spark plugs the same?

No, spark plugs come in a variety of sizes, satisfying the needs of all types of engines such as smaller ones used in lawnmowers and chainsaws. It is very important never to take a ‘one size fits all’ approach. Afterall, NGK SPARK PLUG manufactures well over 1,000 different spark plugs for cars alone, with each car having its own particular spark plug specifications. The company’s catalogues or online part finder are useful tools to identify an engine’s correct plug.

NGK Spark Plugs Technologies

Almost every petrol engine on the market can use NGK spark plugs

From passenger cars and bikes to Formula 1 and motorcycle racing. NGK SPARK PLUG has in over 60 years established itself as a heavily relied upon original equipment manufacturer (OEM). Because of its clear commitment to delivering the highest quality and continuously raising the bar, NGK spark plugs are the first choice for an array of vehicle manufacturers.

In order to meet growing expectations, NGK SPARK PLUG regularly invests in research, technology and development. As a result, the company produces over 1,000 different types of spark plugs for almost every type of engine This includes automotive engines, as well as motorcycles, marine, power sport and many other applications. To sum up, the NGK spark plugs range offers the right product for nearly every demand!

Unique design to guarantee the best possible performance
Wide range of different heat ratings for high thermal endurance
High-performance spark plugs for the newest engine technologies

Spark Plug Requirements

As the main source of power in any petrol engine, a spark plug performs an essential function: It is responsible for igniting the air-fuel mixture in the combustion chamber of petrol engines. This combustion process creates power, which sets the vehicle in motion. To make sure this process runs smoothly, the spark delivered by the spark plug must ignite just before the piston reaches its highest point and the compression is at its greatest.

To make sure the combustion process runs smoothly, the spark delivered by the spark plug must ignite just before the piston reaches its highest point and the compression is at its greatest. The quality of this ignition influences several factors which are of great importance for both the driving operation and the environment. This includes smooth running, performance and efficiency of the engine as well as harmful emissions.

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Types of Spark Plugs

Iridium Spark Plugs

Platinum Spark Plugs

Spark Plugs with Multiple Ground Electrodes

Spark Plugs with V-Groove in the Centre Electrode

Spark Plugs with Supplementary Spark Gap

Semi-surface Ignition Type Spark Plugs

Hybrid Spark Plugs

Racing Spark Plugs

LPG/CNG Spark Plugs

Resources

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Watch the video

This video explains the electrode wear of spark plugs, especialy the difference between single spark and wasted (double) spark systems. It shows in detail why in double spark ignition systems, spark plug electrode wear is different on some cylinders.

Blog: Most common questions about spark plugs

Everything you need to know about the precious ignition part

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Useful Links

TekniWiki Spark Plug and Glow Plug Catalogue Ignition Coils and Leads Catalogue Motorcycle Catalogue Technical Videos Playlist Product Imagery Download

Frequently Asked Questions - Spark Plugs

What does a spark plug do?

What are the symptoms of bad spark plugs?

Why do spark plugs fail?

What metal is used in spark plugs?

How often do you need to change spark plugs?

Is spark plug torque necessary?

What causes carbon fouling on spark plugs?

When should you use colder spark plugs? Do hotter spark plugs make a difference?

Are all spark plugs the same?

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NGK SPARK PLUGS

IGNITING ENDURANCE

Precise Ignition for Petrol Engines

NGK Spark Plugs Technologies

Almost every petrol engine on the market can use NGK spark plugs