Properties of Materials
Material	Thermal Conductivity W/(m•K)	Electrical Conductivity MS/m
Silver	407	66
Copper	384	57
Gold	310	45
Iridium	147	18
Platinum	70	10
Nickel	59	10

Is the heat value of spark plugs important for a car engine?

The heat value (almost always expressed by a number in the centre of the spark plug type marking) is a very
important spark plug parameter. If a plug is chosen that is too hot for the engine, he engine may be destroyed,
if too cold a plug is chosen, the electric insulation resistance will be reduced of the spark plug insulator tip surface
and the plug will cease to ignite the mixture of petrol and air in the ignition chamber.


Should the prescribed electrode distance for spark plugs be maintained?

Of course, always use spark plugs with a prescribed electrode distance. The spark-over voltage between the
electrodes of the spark plugs depends on the electrode distance and therefore the engine ignition system is sized
by this voltage. Likewise the size of the electrode distance depends on the ratio of fuel and air. However what is
decisive is the electrode distance the moment the spark plug replacement interval is reached. Therefore, in some
cases multi-electrode spark plugs or plugs with better quality electrodes such as new ones may have greater electrode
distance.


It is possible to replace spark plugs with various spark gap design?

Generally preference should be given of replacing a spark gap with the same design, nevertheless this does not mean
that spark plugs of different design are worse than the original. In some cases a higher engine output or reduction in
consumption may be achieved.


Do original spark plugs have to be used?

A spark plug is a spare part of an engine that is normalised by international standards. It can therefore be replaced
by a different type of spark plug and it is not important who produced it. However what is important is that it is a good
quality product. Quality systems guarantee product quality. The most well known systems are ISO 9001, VDA 6.1 and
QS 9000. Some car manufacturers condition the guarantee to a car by using the original spare parts and include the
spark plugs among these. This condition is not technically justified.


Why do some spark plugs have a replacement interval of 15 000, 20 000, 30 000, 60 000 and 90 000 km?

The replacement interval depends on the spark gap design of spark plugs and the material used. Generally multi-electrode
plugs and plugs with electrodes made of noble metals have a higher replacement interval than single-electrode ones.


Is it good to replace the spark plug before the expiry of the replacement interval?

The replacement interval is set at an optimum for spark plugs operating in engines. The older the engine, the worse the
conditions for the operation of the spark plugs. Therefore it is good to replace plugs sooner in older engines than waiting
until the replacement interval expires.


What is used to test the correction function of spark plugs?

Today’s engines and spark plugs are of such high quality that during their replacement interval spark plugs are only given
a preventive check. (We recommend once a year)


How do I know when spark plugs need to be replaced?

The first reason for replacing spark plugs is the expiry of their replacement interval. Another signal for replacement is
the jerking of the engine during its acceleration or worse starts. However this may also be caused by the bad condition
of high-voltage cables, cable terminals or the ignition system.


Can BRISK spark plugs be compared with competing top world brands?

BRISK spark plugs are totally comparable with the products of top world firms. They are manufactured in the
production process of a certified quality system as required by car manufacturers in Europe and
America – ISO 9001, VDA 6.1, QS 9000. Among other things these systems guarantee global purchase of
material, supplier assessment, cooperation in engine development, production process management and so on.