This means you can choose any material as long as spark plugs fits by other parameters, yet it’s recommended to use more durable materials since they decrease chances of misfires.įor this relationship we use official documentation from manufacturers, like this one:

They differ by the durability in following order (first the strongest): If you have an older car with little of electronics, you can use both resistor and non-resistor spark plugs.Īll materials works the same. If your car from factory has spark plugs with resistor, use only resisted spark plugs. Resistor surpress RFI and saves your electronics. RFI creates a static electricity, that can accumulate and discharge on car’s electronics and destroy it. Occurring of a spark plug is followed with another event – radio frequency interference (RFI). So it’s crucial to follow the OE dimentions. If it will be too short, spark will occur outside the combustion chamber too long – it’ll collide with the piston. Reach is a distance between spark plug seat and the end of a thread. Note: E3 and Autolite cannot be referenced by heat range. Since all manufacturers have their own heat ranges, we’ve unified all of them to NGK’s chart: heat range “14 (4)” means 14 is the brand’s heat range and 4 is NGK’s equivalent. race engines), some less, but all spark plugs should operate in same temperatures: from 500☌ and below 950☌. This parameter indicates how well spark plug transfer heat from the engine. You physically aren’t able to fit spark plug with another thread, so check it in a first place.

Thread diameter and pitch are fundamental dimensions. That’s why it’s important to stick to OE gap sizes. On the other hand, bigger spark is harder to occur and has more chances to misfire. Bigger gap creates bigger spark, which ignite more fuel. It is essential to use a spark plug that fits a specific engine and its conditions of use.Gap is a distance between center and ground electrodes. NGK Spark Plugs pioneered the use of a copper cored electrode in 1958, which enables a spark plug to heat up quickly and also dissipate heat quickly giving an ultra wide heat range. The spark plug temperature rises too high and induces abnormal combustion (pre-ignition): this leads to melting of the spark plug electrodes as well as piston seizure and erosion. The spark plug temperature remains too low and causes deposits to build up on the firing end the deposits offer an electrical leakage path that gives rise to loss of sparks. Conversely, a high heat range (or cold) spark plug has a short thick insulator nose which will dissipate heat much easier (above right). When a spark plug absorbs heat produced from combustion, the heat is transferred through the centre electrode and insulator nose to the metal shell, which then transfers the heat into the engine casing and circulating coolant.Ī low heat range (or hot) spark plug typically has a long thin insulator nose which will heat up easily however will not dissipate readily to the metal shell (above left). Several factors influence the heat range of a spark plug, although typically the insulator nose design provides an indication of the heat range of a spark plug. High performance engines on the other hand produce a large amount of heat, hence a high heat range (or cold) spark plug such as a 10 heat range needs to be used to resist the heat developed by the engine. This means the spark plug will heat up easily and reach its optimal operating temperature. Generally, low power engines such as lawn mowers don’t produce a large amount of heat, hence use a low heat range (or hot) spark plug such as a 4 heat range. The term hot/cold is commonly used to describe whether a spark plug heats up easily (hot) or whether it provides resistance to heating up (cold). This number indicates the thermal characteristics of a spark plug, or how ‘hot’ or ‘cold’ a spark plug is. Typically the heat range for NGK Spark Plugs varies from 2-11.

Ngk heat range chart