====This is an info thread, post if you have extra info or corrections to info to be made====
So this is going to be a sort of tech archive on spark plugs, will run thru the basics first and then give some more in depth that you may not have known
i kno i sure learnt alot doing research on this, alot of it is directly quoted from various places on the web that i found the info and the links will be at the bottom of the post if you are interested
onto the info
===================
The Basics:
The primary function of the spark plug is to ignite the air/fuel mixture within the combustion chamber under any operating condition.
Spark plugs must provide a path and a location for electrical energy from the ignition coil to create a spark used to ignite the air-fuel mixture. A sufficient amount of voltage must be supplied by the ignition system to spark across the spark plug gap. This is called “Electrical Performance.”
The spark plug firing end temperature must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called “Thermal Performance”, and is determined by the heat range selected.
Heat Rating:
NGK Spark Plugs Heat Rating
The spark plug heat range has no relationship to the electrical energy transferred through the spark plug. The heat range of a spark plug is the range in which the plug works well thermally. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type
Some factors to consider in selecting the proper heat range spark plug
There are many external influences that can affect the operating temperature of a spark plug. The following is a brief list to consider in avoiding reduced performance and/or expensive engine damage.
Engine Speed and Load
* If the engine is to be operated at high RPM, under a heavy load, or at high temperatures for long periods a colder heat range may be needed.
* Conversely, if the engine is to be operated at low speeds or at low temperatures for long periods, a hotter heat range might be needed to prevent fouling.
Air-Fuel Mixture
* Excessively rich air-fuel mixtures can cause the plug tip temperatures to decrease and carbon deposits to accumulate, possibly causing fouling and misfires.
* Excessively lean air-fuel mixtures can cause the cylinder and plug temperatures to increase, possibly resulting in knock and/or pre-ignition. This may cause damage to the spark plug and/or seriously damage the engine.
* If an air-fuel ratio meter or gas analyzer is not available, it will be necessary to visually inspect the spark plugs frequently during the tuning process to determine the proper air-fuel mixture.
Fuel Type / Quality
* Low quality and/or low octane fuel can cause knock which will elevate cylinder temperatures. The increased cylinder temperature will cause the temperature of the combustion chamber components (spark plug, valves, piston, etc.) to rise, and will lead to pre-ignition if the knock is uncontrolled.
* When using an ethanol blend fuel with high ethanol content in high performance applications, a colder heat range may be necessary. The spark timing can be advanced further because ethanol blend fuel has a higher resistance to knock (higher octane). Due to the decreased knock, there will be less audible “warning” from knock before the spark plug overheats and pre-ignites.
Some types of fuel additives in lower quality fuels can cause spark plug deposits that can lead to misfires, pre-ignition, etc.
Ignition Timing
* Advancing ignition timing by 10° will cause the spark plug tip temperature to increase by approximately 70° to 100°C.
* A colder heat range spark plug may be necessary if the ignition timing has been advanced to near the knock level. Higher cylinder temperatures near the knock level will bring the spark plug firing end temperature closer to the pre-ignition range.
Compression Ratio
* Significantly increasing the static/dynamic compression ratio will increase cylinder pressures and the octane requirement of the engine. Knock may occur more easily. If the engine is operated near the knock level, a colder heat range spark plug may be necessary due to the resulting increased cylinder temperatures.
Forced Induction (Turbocharging, Supercharging)
* A colder heat range spark plug may be necessary due to the increased cylinder temperature as boost pressure (manifold pressure) and subsequent cylinder pressure and temperature increase.
Ambient Air Temperature / Humidity
* As the air temperature or humidity decreases, the air density increases, requiring a richer air-fuel mixture. If the air-fuel mixture is not properly richened, and the mixture is too lean, higher cylinder pressures / temperatures, knocking, and the subsequent increase in the spark plug tip temperatures can result.
* As the air temperature or humidity increases, the air density decreases, requiring a leaner air-fuel mixture. If the air-fuel mixture is too rich, decreased performance and/or carbon fouling can result.
Barometric Pressure / Altitude
* Air (atmospheric) pressure and cylinder pressure decrease as altitude increases. As a result, spark plug tip temperature will also decrease.
* Fouling can occur more easily if the air-fuel mixture is not adjusted to compensate for the altitude. Higher altitude = less air = less fuel.
Types of Abnormal Combustion
Pre-ignition
* Pre-ignition occurs when the air-fuel mixture is ignited by a hot object / area in the combustion chamber before the timed spark event occurs.
* When the spark plug firing end (tip) temperature exceeds 800°C, pre-ignition originating from the overheated insulator ceramic can occur.
* Is most often caused by the wrong (too hot) heat range spark plug, and/or over-advanced ignition timing. An improperly installed (insufficient torque) spark plug can also result in pre-ignition due to inadequate heat transfer.
* Pre-ignition will dramatically raise the cylinder temperature and pressure and can melt and hole pistons, burn valves, etc.
Knock
* Occurs when part of the air-fuel mixture in the combustion chamber away from the spark plug is spontaneously ignited by the pressure from a flame front originating from the spark plug. The two colliding flame fronts contribute to the “knocking” sound.
* Knock occurs more frequently when using low octane fuel. Low octane fuel has a low resistance to knock (low resistance to ignition)
* Knock is related to ignition timing. (Knock is sometimes referred to as “Spark-knock”.) Retarding the ignition timing will reduce knock.
* Heavy knock often leads to pre-ignition.
* Heavy knock can cause breakage and/or erosion of combustion chamber components.
* Knock is sometimes referred to as “ping” or “detonation”.
Misfires
* A misfire occurs when the spark travels the path of least resistance instead of jumping across the gap. Misfires can be caused by the following:
1. Carbon fouling
2. Worn or deteriorated ignition system components
3. Too large of gap size
4. Spark timing excessively advanced or retarded
5. Damaged spark plugs (cracked insulator, melted electrodes, etc)
6. Mismatched ignition system components (plug resistance / wire resistance, ignition coils / igniter modules, etc.)
7. Insufficient coil primary and/or secondary voltage – voltage required to jump the spark plug gap higher than coil output
sources for info:
http://www.ngksparkplugs.com/tech_suppo ... p?mode=nml
http://en.wikipedia.org/wiki/Spark_plug
So this is going to be a sort of tech archive on spark plugs, will run thru the basics first and then give some more in depth that you may not have known
i kno i sure learnt alot doing research on this, alot of it is directly quoted from various places on the web that i found the info and the links will be at the bottom of the post if you are interested
onto the info
===================
The Basics:
The primary function of the spark plug is to ignite the air/fuel mixture within the combustion chamber under any operating condition.
Spark plugs must provide a path and a location for electrical energy from the ignition coil to create a spark used to ignite the air-fuel mixture. A sufficient amount of voltage must be supplied by the ignition system to spark across the spark plug gap. This is called “Electrical Performance.”
The spark plug firing end temperature must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called “Thermal Performance”, and is determined by the heat range selected.
Heat Rating:
NGK Spark Plugs Heat Rating
The spark plug heat range has no relationship to the electrical energy transferred through the spark plug. The heat range of a spark plug is the range in which the plug works well thermally. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type
Some factors to consider in selecting the proper heat range spark plug
There are many external influences that can affect the operating temperature of a spark plug. The following is a brief list to consider in avoiding reduced performance and/or expensive engine damage.
Engine Speed and Load
* If the engine is to be operated at high RPM, under a heavy load, or at high temperatures for long periods a colder heat range may be needed.
* Conversely, if the engine is to be operated at low speeds or at low temperatures for long periods, a hotter heat range might be needed to prevent fouling.
Air-Fuel Mixture
* Excessively rich air-fuel mixtures can cause the plug tip temperatures to decrease and carbon deposits to accumulate, possibly causing fouling and misfires.
* Excessively lean air-fuel mixtures can cause the cylinder and plug temperatures to increase, possibly resulting in knock and/or pre-ignition. This may cause damage to the spark plug and/or seriously damage the engine.
* If an air-fuel ratio meter or gas analyzer is not available, it will be necessary to visually inspect the spark plugs frequently during the tuning process to determine the proper air-fuel mixture.
Fuel Type / Quality
* Low quality and/or low octane fuel can cause knock which will elevate cylinder temperatures. The increased cylinder temperature will cause the temperature of the combustion chamber components (spark plug, valves, piston, etc.) to rise, and will lead to pre-ignition if the knock is uncontrolled.
* When using an ethanol blend fuel with high ethanol content in high performance applications, a colder heat range may be necessary. The spark timing can be advanced further because ethanol blend fuel has a higher resistance to knock (higher octane). Due to the decreased knock, there will be less audible “warning” from knock before the spark plug overheats and pre-ignites.
Some types of fuel additives in lower quality fuels can cause spark plug deposits that can lead to misfires, pre-ignition, etc.
Ignition Timing
* Advancing ignition timing by 10° will cause the spark plug tip temperature to increase by approximately 70° to 100°C.
* A colder heat range spark plug may be necessary if the ignition timing has been advanced to near the knock level. Higher cylinder temperatures near the knock level will bring the spark plug firing end temperature closer to the pre-ignition range.
Compression Ratio
* Significantly increasing the static/dynamic compression ratio will increase cylinder pressures and the octane requirement of the engine. Knock may occur more easily. If the engine is operated near the knock level, a colder heat range spark plug may be necessary due to the resulting increased cylinder temperatures.
Forced Induction (Turbocharging, Supercharging)
* A colder heat range spark plug may be necessary due to the increased cylinder temperature as boost pressure (manifold pressure) and subsequent cylinder pressure and temperature increase.
Ambient Air Temperature / Humidity
* As the air temperature or humidity decreases, the air density increases, requiring a richer air-fuel mixture. If the air-fuel mixture is not properly richened, and the mixture is too lean, higher cylinder pressures / temperatures, knocking, and the subsequent increase in the spark plug tip temperatures can result.
* As the air temperature or humidity increases, the air density decreases, requiring a leaner air-fuel mixture. If the air-fuel mixture is too rich, decreased performance and/or carbon fouling can result.
Barometric Pressure / Altitude
* Air (atmospheric) pressure and cylinder pressure decrease as altitude increases. As a result, spark plug tip temperature will also decrease.
* Fouling can occur more easily if the air-fuel mixture is not adjusted to compensate for the altitude. Higher altitude = less air = less fuel.
Types of Abnormal Combustion
Pre-ignition
* Pre-ignition occurs when the air-fuel mixture is ignited by a hot object / area in the combustion chamber before the timed spark event occurs.
* When the spark plug firing end (tip) temperature exceeds 800°C, pre-ignition originating from the overheated insulator ceramic can occur.
* Is most often caused by the wrong (too hot) heat range spark plug, and/or over-advanced ignition timing. An improperly installed (insufficient torque) spark plug can also result in pre-ignition due to inadequate heat transfer.
* Pre-ignition will dramatically raise the cylinder temperature and pressure and can melt and hole pistons, burn valves, etc.
Knock
* Occurs when part of the air-fuel mixture in the combustion chamber away from the spark plug is spontaneously ignited by the pressure from a flame front originating from the spark plug. The two colliding flame fronts contribute to the “knocking” sound.
* Knock occurs more frequently when using low octane fuel. Low octane fuel has a low resistance to knock (low resistance to ignition)
* Knock is related to ignition timing. (Knock is sometimes referred to as “Spark-knock”.) Retarding the ignition timing will reduce knock.
* Heavy knock often leads to pre-ignition.
* Heavy knock can cause breakage and/or erosion of combustion chamber components.
* Knock is sometimes referred to as “ping” or “detonation”.
Misfires
* A misfire occurs when the spark travels the path of least resistance instead of jumping across the gap. Misfires can be caused by the following:
1. Carbon fouling
2. Worn or deteriorated ignition system components
3. Too large of gap size
4. Spark timing excessively advanced or retarded
5. Damaged spark plugs (cracked insulator, melted electrodes, etc)
6. Mismatched ignition system components (plug resistance / wire resistance, ignition coils / igniter modules, etc.)
7. Insufficient coil primary and/or secondary voltage – voltage required to jump the spark plug gap higher than coil output
sources for info:
http://www.ngksparkplugs.com/tech_suppo ... p?mode=nml
http://en.wikipedia.org/wiki/Spark_plug