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NGK
Spark Plugs (USA), Inc.
was established in 1966, a subsidiary of NGK Spark Plug Co., Ltd. in Japan, as a
means to distribute high quality products in the United States market.
The NGK Spark Plugs division is responsible for spark plug, wire and cap
sales and U.S. spark plug manufacturing facilities.
NGK
Spark Plugs has earned the reputation of being a world leader in innovation and
quality in each of our product lines. We will continue this commitment to
excellence in the future.
Ceramics
has always been the core of our businessWe rate technological excellence as our
highest goal. With full use of the most suitable technologies available to us,
and our aggregate experience, we continue to strive to offer new values to the
peoples of the world through our products.
NGK Spark
Plugs commitment to its customers, to society, and to the world is to offer
innovative, superior, and competitive products that are useful and support the
needs of the consumer.
1.
Installing spark plugs
Torque is one
of the most critical aspects of spark plug installation.
Torque
directly affects the spark plugs' ability to transfer heat out of the combustion
chamber. A spark plug that is under-torqued will not be fully seated on the
cylinder head, hence heat transfer will be slowed. This will tend to elevate
combustion chamber temperatures to unsafe levels, and pre-ignition and
detonation will usually follow. Serious engine damage is not far behind.
An over-torqued
spark plug can suffer from severe stress to the Metal Shell which in turn can
distort the spark plug's inner gas seals or even cause a hairline fracture to
the spark plug's insulator. In
either case, heat transfer can again be slowed and the above mentioned
conditions can occur.
The spark plug
holes must always be cleaned prior to installation, otherwise you may be
torquing against dirt or debris and the spark plug may actually end up under-torqued,
even though your torque wrench says otherwise. Of course, you should only
install spark plugs in a cool engine, because metal expands when it’s hot and
installation may prove difficult.
Proper
torque specs for both aluminum and cast iron cylinder heads are listed below.
2.
Gapping
Since the gap
size has a direct affect on the spark plugs' tip temperature and on the voltage
necessary to ionize (light) the air/fuel mixture, careful attention is required.
While it is a popular misconception that plugs are pre-gapped from the factory,
the fact remains that the gap must be adjusted for the vehicle that the spark
plug is intended for.
Those with
modified engines must remember that a modified engine with higher compression or
forced induction will typically require a smaller gap settings (to ensure
ignitability in these denser air/fuel mixtures). As a rule, the more power you
are making, the smaller the gap you will need.
A spark plug's
voltage requirement is directly proportionate to the gap size. The larger the
gap, the more voltage is needed to bridge the gap. Most experienced tuners know
that opening gaps up to present a larger spark to the air/fuel mixture,
maximizing burn efficiency. It is for this reason that most racers add high
power ignition systems. The added
power allows them to open the gap, yet still provide a strong spark.
With this in
mind, many think the larger the gap the better. In fact, some after-market
ignition systems boast that their
systems can tolerate gaps that are extreme, be wary of such claims.
In most cases, the largest gap you can run may still be smaller than you
think.
3.
Indexing
This is for
racers only !!
Indexing
refers to a process whereby auxiliary washers of varying thickness are placed
under the spark plug's shoulder so that when the spark plug is tightened, the
gap will be pointed in the desired direction.
However,
without running an engine on a dyno., it is impossible to gauge which type of
indexing works best in your engine. While
most engines like the spark plug's gap open to the intake valve, there are still
other combinations that make more power with the gap pointed toward the exhaust
valve.
In any case,
engines with indexed spark plugs will typically make only a few more horsepower,
typically less than 1% of total engine output.
For a 500hp engine, you'd be lucky to get 5hp.
While there are exceptions, the bottom line is that without a dyn.,
gauging success will be difficult.
4.
Heat Range selection
Let's
make this really simple: when you need your engine to run a little cooler, run a
colder plug. When you need your
engine to run a little hotter, run a hotter spark plug. However, NGK strongly
cautions people that going to a hotter spark plug can sometimes mask a serious
symptom of another problem that can lead to engine damage. Be very careful with
heat ranges. Seek professional
guidance if you are unsure.
With modified
engines (those engines that have increased their compression), more heat is a
by-product of the added power that normally comes with increased compression.
In short,
select one heat range colder for every 75-100 hp you add, or when you
significantly raise compression. Also
remember to retard the timing a little and to increase fuel enrichment and
octane. These tips are critical when adding forced induction (turbos,
superchargers or Nitrous kits), and failure to address ALL of these areas will
virtually guarantee engine damage.
An engine that
has poor oil control can sometimes mask the symptom temporarily by running a
slightly hotter spark plug. While this is a "Band-Aid" approach, it is
one of the only examples of when and why one would select a hotter spark plug.
5. Using "racing" spark plugs
Be cautious!!
In reality, most "racing" spark plugs are just colder heat
ranges of the street versions of the street spark plug.
They don't provide any more voltage to the spark plug tip!!
Their internal construction is no different (in NGK's case, as all of our
spark plugs must conform to the same level of quality controls) than most
standard spark plugs.
There are some
exceptions, though. Extremely high compression cars or those running exotic
fuels will have different spark
plug requirements and hence NGK makes spark plugs that are well-suited for these
requirements. They are classified
as "specialized spark plugs for racing applications".
Some are built with precious metal alloy tips for greater durability of
for their ability to fire in denser or leaner air/fuel mixtures.
However,
installing the same spark plugs Kenny Bernstein uses in his 300+mph Top Fuel car
(running Nitromethane at a 2:1 air/fuel ratio and over 20:1 dynamic compression)
in your basically stock Honda Civic (running 15:1 a/f ratios with roughly 9.5:1
compression) will do nothing for you!! In fact, since Kenny's plugs are fully 4
heat ranges colder, they'd foul out in your Honda in just a few minutes.
NGK as a
company tries to stay clear of saying that a racing spark plug (or ANY spark
plug) will give you large gains in horsepower.
While certain spark plugs are better suited to certain applications (and
NGK/Toysport is happy to counsel you in the right direction) NGK tries to tell
people that are looking to "screw in" some cheap horsepower that, in
most cases, spark plugs are not the answer.
To be blunt,
when experienced tuners build race motors, they select their spark plugs for
different reasons: to remove heat more efficiently, provide sufficient spark to
completely light all the air/fuel mixture, and to survive the added stresses
placed upon a high performance engine's spark plugs, and to achieve optimum
piston-to-plug clearance.
Some of these
"specialized racing plugs" are made with precious metal alloy
center/ground electrodes or fine wire tips or retracted-nose insulators.
Again, these features do not necessarily mean that the spark plug will
allow the engine to make more power, but these features are what allow the spark
plug to survive in these tortuous conditions.
Most racers know screwing in a new set of spark plugs will not magically
"unlock" hidden horsepower.
6.
Using high power ignition systems
Many of the
more popular after-market ignition systems are of the capacitive discharge type.
They store voltage, or accumulate it, until a point at which a trigger
signal allows release of this more powerful spark. Companies like Mallory, MSD,
Crane and Accel, to name a few, offer such systems.
They affect
spark plugs in that they allow the gaps to be opened up to take advantage of the
increased capacity. The theory is that the larger and the more intense the spark
you are able to present to the air/fuel mixture, the more likely you will be to
burn more fuel, and hence the more power you will make.
We encourage the use of such systems, but only on modified or older
non-computer controlled vehicles.
In reality,
computer controlled vehicles do such a good job of lighting off the air/fuel
mixture (as evidence by the ultra-low emissions), added ignition capacity would
do little to burn more fuel since the stock configuration is doing such a good
job. Older non-computer controlled vehicles or those that have been modified
with higher compression or boosted (nitrous, turbo, supercharged) engines can
certainly take advantage of a more powerful ignition system.
What
are the primary functions of a spark plug?
The spark plug
performs four main functions:
1.
It fills a hole in
the cylinder head.
2.
It acts as a
dielectric insulator for the ignition system.
3.
It provides spark for
the combustion process to occur.
4.
It removes heat from
the combustion chamber.
It is
important to remember that spark plugs do not create heat, they help remove it.
Anything that prevents a spark plug from removing the proper amount of heat can
lead to pre-ignition, detonation, premature spark plug failure and even internal
engine damage, especially in two stroke engine or modified engines.
In the
simplest of terms, the spark plug acts as the thermometer of the engine.
Much like a doctor
examining a
patient, this "thermometer" can be used by mechanics to effectively
diagnose the amount of heat present in each combustion chamber.
The
experienced technician will then be able to interpret the plugs' visual cues and
accurately determine the engine's overall operating condition, get a feel for
air/fuel ratios, and even diagnose driveability problems, provided the
technician has received proper training.
Spark plugs
are valuable tuning tools, when interpreted correctly. They will show symptoms
of other problems and can reveal a great deal about the engine's overall
condition. The experienced technician will evaluate the appearance of the spark
plug's firing tip and will begin to make a diagnosis or some basic assumptions
based on the physical appearance of the spark plugs.
Why
do we need to change spark plugs in the first place?
As spark plugs
grow older, they lose their sharp edges and material from the center and ground
electrodes is slowly eroded away.
As the gap
between these two points grows, the voltage required to bridge this gap
increases proportionately.
The ignition
system must work harder to compensate for this higher voltage requirement and
hence there are a greater rate of misfires, or incomplete combustion cycles.
Each misfire means lost horsepower,
reduced fuel economy and higher emissions.
Replacing worn out spark plugs with new ones (with sharp new edges)
effectively restores the ignition system's efficiency and reduces the percentage
of misfires, restoring power, economy, and reducing emissions.
How long spark
plugs last will depend on a variety of factors, including engine compression,
fuel used, gap, center/ground electrode material, how the vehicle is used, etc.
A common
misconception is that changing spark plugs will sometimes result in large power
gains. In most cases, removing even
seriously worn out spark plugs will only result in very modest power gains,
typically about 1%-2% of total engine output, perhaps less for computer
controlled vehicles, primarily because most newer vehicles have more powerful
ignition systems and the vehicle's computer can take adjustments to make vehicle
operation seem smoother and more seamless.
Many people
think that simply supplying more spark to the firing tip can/will combust more
fuel. What most people don't understand is that most newer cars engine's are so
efficient that they are already burning all of the available fuel.
Simply adding more spark or voltage can't burn any more fuel, because
there is no more fuel to burn!!
But, as time
goes on, the spark plugs lose much of their electrode surface area to natural
erosion and even the best ignition systems will be strained to supply enough
voltage to bridge the gap. Some
fuel is left unburned, and it is at this point that a spark plug change becomes
necessary.
In most cases,
not until the engine is modified or compression is raised significantly that
stock ignition systems and standard spark plugs begin to show signs of
inadequacies.
At this point,
a variety of factors will determine which spark plug would be best suited for a
particular application. In these modified engines, specific electrode/tip
configurations, electrode materials, and colder heat ranges can indeed provide
measurable gains in power, but only in highly modified engines.
When a stock
or near stock engine is given a fresh set of spark plugs, peak efficiency is
restored, and the power gains that come from this restored state of tune are
usually minimal. Any company that
tells you that their spark plug will provide significant gains in power in a
stock or near stock engine is making blanket statements that may be
insupportable.
What is a heat range? When should I change heat ranges?
A heat range
refers to how much heat a spark plug is capable of removing from the combustion
chamber. Remember, spark
plugs DO NOT create heat.
Selecting a
spark plug with the proper heat range will ensure that the tip will maintain a
temperature
high enough to
prevent fouling, yet be cool enough to prevent pre-ignition.
While there
are many other things that can cause pre-ignition, selecting the proper heat
range spark plug will ensure that the spark plug itself is not a hot-spot
source.
For NGK Spark
Plugs, every heat range colder translates into the ability to remove 70-100
degrees Celsius more heat.
As a rule of
thumb, every time you increase compression by one point, or for every 75-100 hp
you add, go at least one step colder. Remember,
it is better to go colder than is thought necessary.
The worst that can happen in this scenario is that the plugs will foul
out. If you inadvertently select a
heat range that is too hot, the resulting pre-ignition and detonation can cause
serious engine damage.
What
is a "projected nose" spark plug?
Is it better than a conventional plug?
The term
"projected nose" refers to the Insulator nose length.
If it protrudes beyond the tip of the spark plug's metal shell, it is
said to be projected.
If the
combustion chamber design can accommodate this slightly longer nose, this can be
advantageous in that it might place the spark closer to the center of the
combustion chamber, assisting in quick, even, and complete combustion.
It can have an
affect similar to slightly advancing the timing. However, one must be careful
that there is adequate clearance for this additional projection or
piston-to-plug interference problems can occur.
Yes and no.
A spark plug part number might fit hundreds of engines, and although the
factory will typically set gap to a pre-selected setting, this gap may not be
the right one for your particular engine, and may not take into account
modifications that you may have performed to the engine.
Insufficient
spark plug gap can cause pre-ignition, detonation, even engine damage.
Too much gap can result in a higher rate of misfires, noticeable loss of
power, plug fouling, and poor economy.
When you raise
compression or add forced induction (a turbo system, nitrous, or supercharger
kit), you must lower the gap (reduce gap about .004" for every 50 hp you
add). However, when you add a high power ignition system (such as those offered
by MSD, Crane, Nology,) you can open the gap back up about
.002"-.005".
As an example,
let's use a hypothetical `96 350 Chevrolet LT1 engine build-up, standard gap is
.050" for an un-modified LT1. We'll add 150hp Nitrous.
So we must lower the gap about .012" to .038". We then decide
to add that killer MSD 6A/Crane Hi-6 box and, using our guidelines as outlined
above, we can now open the gap up .002"-.005" to about .040"-
.043". Following this basic
guideline should get you very close.
Further
experimentation may be necessary, but by always starting with a larger gap than
it thought necessary to reduce the risk of detonation, you should be safe.
First, you must consider the thread reach, the thread diameter, the Insulator nose projection, and observe whether the spark plug incorporates a gasket or is of the conical type.
You can refer
to the NGK Master Catalog for your exact
application or check the application section with Toysport.
You should
also consider how the vehicle is used (i.e:
racing, towing), take into account any modifications you have performed and the
fuel being used (alcohol, race gas, CNG, etc.).
Contact the
NGK Tech Support Group or Toysport for questions about specific applications.
Toysport or
the NGK Master Catalog can give you the correct NGK part number for your
application. All spark plug
manufacturers provide such information. It
is best to consult the application sections of these catalogs rather than using
a cross-reference guide.
The term
"modified" refers to those engines that have received bolt-on
improvements that may or may not raise the engine's total compression ratio.
These mods can include Turbo-charging, super-charging, nitrous oxide injection,
the use of smaller chambered cylinder heads, revised piston configurations, free
flowing cylinder heads, change of induction components and/or the use of
different fuel types and octane.
Mods that will
typically NOT require specialized plugs (and in most cases the factory-installed
plug will be more than adequate for the application) include adding a
free-flowing air filter, headers, mufflers, rear-end gears. Basically,
any modification that does not alter the overall compression ratio will not
usually necessitate switching plug types or heat ranges. (These minor
modifications will not significantly increase the amount of heat in the
combustion chamber and hence a plug change is probably not warranted).
However, when
compression is raised, along with the added power comes added heat. Since spark
plugs must remove heat and a modified engine makes more heat, the spark plug
must remove more heat. A colder
heat range spark plug must be selected, and spark plug gaps should be adjusted
smaller to ensure proper ignitability in this denser air/fuel mixture.
Typically, for
every 75-100 hp you add, you should go one step colder on the spark plug's heat
range. Going to a hotter heat range is not usually recommended, except when
severe oil or fuel fouling is occurring.
Contact
Toysport or the NGK Tech Dept. if you have a very special combination or are
using a different fuel (alcohol, methanol, race gas, etc.)
How
do I "read" a spark plug?
Reading spark plugs can be a valuable tuning aid. By examining the Insulator
firing nose color, an experienced engine tuner can determine much about the
engine's overall operating condition.
In general, a
light tan/gray color tells you that the spark plug is at the optimum temperature
and that the engine is in good operating condition.
Dark coloring,
such as heavy black wet or dry deposits usually indicate a fouling problem.
Heavy, dry deposits can indicate an overly rich condition, too cold a
heat range spark plug, possible vacuum leak, low compression, overly retarded
timing, or too large a plug gap.
If the
deposits are wet, it can be an indication of a breached head gasket, oil control
from rings or valve train problems, or an extremely rich condition, depending on
what liquid is present at the firing tip.
One must also
look for signs of detonation, such as silver specs, black specs, or melting or
breakage at the firing tip.
Signs of
fouling or excessive heat must be traced quickly to prevent further
deterioration of performance and to prevent possible engine damage.
For a visual
reference by which to compare your plugs for reading, be sure to click on the
following links to view and save these handy charts: (See NGK Web site)
Normal,
Deposits, Dry/Wet Fouling, Lead Fouling, Overheating & Breakage
Abnormal Erosion, Melting, Corrosion/Oxidation, and Lead Erosion
What
is a "fouled" spark plug?
A spark plug
is said to be fouled when the Insulator nose at the firing tip becomes coated
with a foreign substance, such as fuel, oil, or carbon.
This coating
makes it easier for the voltage to follow along the insulator nose and leach
back down into the metal shell, grounding out, rather than bridging the gap
normally.
Fuel, oil, and
carbon fouling can all be caused by different things, but in any case, once a
spark plug is fouled, it will not provide voltage to the firing tip and that
cylinder will not fire properly.
In many cases,
the spark plug cannot be cleaned sufficiently to restore normal operation. It is
therefore recommended that fouled plugs be replaced.
It takes only
1,000 volts to pass through the resistor and even the weakest and most primitive
ignition systems are easily capable to pushing voltage through a resistor.
Today's ignition systems are easily capable of sustaining well over 20,000
volts.
In fact, using
a non-resistor plug in certain applications can actually cause the engine to
suffer some strange side effects, such as an erratic idle, high rpm misfire,
engine run-on, power drop-off at certain rpm levels, and abnormal combustion.
This is because resistor spark plugs reduce electromagnetic interference with
on-board electronics.
In English,
this means stray voltage can "talk back" to on-board electronic
systems, confusing them. In some cases, engine damage can occur.
NGK and
Toysport strongly recommends using resistor spark plugs in any vehicle that uses
on-board computer systems to monitor or control engine performance, or on any
vehicle that has other on-board electronic systems such as Engine Management
computers, two way radios, GPS systems, depth finders, etc., or whenever
recommended by the engine manufacturer.
What does it
mean if the spark plug tip is broken, missing or melting? When a spark plug tip shows signs of melting or is broken, it
usually means that excessive heat and/or detonation was present in that
particular combustion chamber, or that the spark plug was suffering from thermal
shock.
Since spark
plugs do not create heat by themselves, one must use this visual clue to track
down the root cause of the problem.
In any case,
damaged firing tips most often indicate that cylinder pressures or temperatures
were too high. Left unresolved,
this condition usually results in more serious engine damage.
What
is "detonation" and how does it affect the spark plug?
Detonation
refers to a type of abnormal combustion that is usually preceded by
pre-ignition. It is most often caused by a hot spot formed in the combustion
chamber. As air and fuel is drawn
into the combustion chamber during the intake stroke, this hot spot will
"pre-ignite" the air fuel mixture without any spark from the spark
plugs.
Detonation
exerts a great deal of downward force on the pistons as they are being forced
upward by the mechanical action of the connecting rods. When this occurs, the
resulting concussion, shock waves and heat can be severe.
Spark plug tips can be broken, or melted, and other internal engine
components such as the pistons or connecting rods themselves can be damaged.
Left
unresolved, engine damage is almost certain to occur, with the spark plug
usually suffering the first signs of damage.
Remember, when
you observe signs of detonation or pre-ignition by examining the spark plugs'
firing tip, you are observing a symptom of another problem.
The trick is
to figure out what caused the hot spot to form in the first place. You should
seek professional guidance to determine the root cause of the problem.
Please review
the following reference chart to examine the symptoms, causes, and results of
knock and pre-ignition. (See
NGK Web site)
Will
they give me multiple sparks?
No, a spark
plug with more than one ground electrode will NOT give you more than one spark
at a time. Electricity is lazy, so it will always follow the path of least
resistance. In the case of spark
plugs with multiple ground electrodes, one ground electrode surface will always
be just a little closer than the other, and hence it will receive the spark. As
this surface begins to wear, the next closest ground electrode will then start
receiving the spark.
Then why use
them in the first place? NGK offers
many spark plugs with multiple electrode configurations.
Each type is designed for a specific application, such as high voltage
ignition systems with extremely high cylinder pressures, including some outboard
engines, rotary engines and some import applications. The extra ground
electrodes serve only to keep the ground electrodes cooler, extend the life of
the plug, remove more heat, and to fire effectively in certain combustion
chamber configurations where single electrode spark plugs would foul.
They will usually not deliver more power in a non-specified application, and the fact that some of these are a much colder heat range than average spark plugs makes them very susceptible to fouling when used outside of their recommended application.
To suggest
that multiple ground electrode spark plugs hold some performance advantage over
single electrode spark plugs would be citing an exception rather than the rule,
be wary of such claims.
Should
I use "never-seize" compound on the threads?
Not with NGK
Spark Plugs. Our spark plugs are manufactured with a cold rolled thread,
ensuring smooth, burr-free threads that are safe and will not cut new threads,
even on aluminum cylinder heads.
Many other
spark plug companies still use machine-cut threads, and the burrs and sharpness
of these threads can cause cylinder head damage...with these other spark plugs,
the use of never-seize is probably
a good idea. Be sure not to get any of this coating on the spark plug's firing
tip, or the spark plug will not function correctly.
What
is "indexing" and how much more power will I get?
Indexing
refers to an old racer's trick whereby the spark plugs are installed so that the
ground electrode is oriented to face the intake valve (usually) in an effort to
"open up" the spark to the incoming
air/fuel charge. This is accomplished by placing a washer underneath the spark
plug's shoulder area (of a
specified thickness) so that after properly torquing the spark plug, the
electrode would be pointed in the desired direction, usually towards the
incoming air/fuel charge from the intake valve.
Some racers
have discovered that certain engine configurations made more power with the
spark plug pointed away from the air fuel mixture.
It is
important to note that any power increase will be small, typically 1-2% of total
engine output, and the proper indexing orientation can only be discovered after
extensive engine dyno testing.
Indexing is a
waste of time for racers that do not have the training or the dyno facilities to
document the results of their efforts. However, professional race teams racing
in classes that have strict engine specifications can gain a slight edge over
their competitors when spark plugs are indexed for optimum performance, provided
they have performed adequate dyno testing.
How much should I tighten my spark plugs?
Torque is one
of the most critical aspects of installing spark plugs.
A spark plug
that is under torqued will not be able to effectively remove heat, because the
shoulder of the spark plug is not properly seated. This prevents the spark plug from transferring heat to the
cylinder head. In severe cases, combustion gases can actually leak out past the
threads. This will usually cause the spark plug to become severely overheated,
resulting in spark plug melting, breakage due to thermal shock, or even more
serious engine damage.
A spark plug
that is over torqued can suffer distorted inner combustion gas seals, or a
hairline fracture of the Insulator. The spark plug's insulation resistance (its
ability to keep the spark inside) or the spark plug's ability to remove heat can
be adversely affected. The spark
plug will again be unable to transfer heat effectively, combustion chamber
temperatures will skyrocket and engine damage can be the result.
Different
thread diameter spark plugs require different torque specs. For most 14mm spark
plugs, about 18-22 lb/ft is accurate. Aluminum
heads will take slightly less torque than cast iron heads.
As a basic rule, for gasket type spark plugs,
use 1/2 - 3/4 of a turn after finger tight.
For taper seat spark plugs, use only 1/16 - 1/8 of a turn after finger
tight.
Remember to
never install spark plugs into a hot engine as metal expands when its hot, and
the spark plugs may become seized or try to "cut" new threads.
Permanent cylinder head damage or a seized spark plug may result.
Below you will
find the recommended tightening torques for NGK Spark Plugs.
Please call our Technical Department should you have any questions
related to the installation, care, and maintenance of your NGK Spark Plugs.
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