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Spark plugs
frequently asked questions |
1. I know my standard spark plug part number but how can I find a
performance equivalent?
2. My engine has been tuned/modified, do I need a colder/hotter
plug?
3. My vehicle has been modified to run LPG (liquid propane gas) or
dual fuel, do I need to change my spark plugs to allow for this?
4. Will I get a noticeable power increase if I replace my standard
plugs with Iridium plugs?
5. Which Iridium plugs are better? NGK Iridium IX or Denso Iridium
Power?
6. How long should my spark plugs last?
7. Can you send me a catalogue/patch/promotional item from
NGK/Denso/Champion
8. Why do some spark plugs have multiple ground electrodes?
9. Do my multi ground electrode plugs outperform single ground
plugs?
10. Can I replace my multi ground plugs with a single ground Iridium
plug?
11. What do the different letters and numbers mean in my spark
plug's part code?
12. Why isn't my vehicle listed in your application guides? How can
I find what plugs my vehicle should use?
13. What should my spark plug gap be set to?
14. Should I regap my Iridium spark plugs?
15. How do I regap my spark plugs?
16. What is the correct torque setting for my engine/spark plugs?
17. Are there any other factors which may affect which heat range
plug I use?
18. Can you tell me which NGK, Champion and Denso plugs are suitable
for my car?
19. Can you supply a resistorless equivalent part for use with
Nitrous Oxide?
20. What sparkplugs do I need for a Mazda RX7?
21. What is the difference between the ISO and JIS standards? (BCPR
and BKR or IK and IQ etc)
22. Why haven't you answered my enquiry?
Q1. I know my standard spark plug part number but how can I find a
performance equivalent?
A1. Use our partsearch facility. Type in your original part number
and click 'search'. Your part should be displayed along with a
'X-ref' button (if this doesn't appear then there are no equivalent
plugs listed in our database). Click the 'X-ref' button, read and
accept our disclaimer and spark plugs with the same dimensions but
different constructions (e.g. copper, platinum, iridium) will be
displayed. You can click the shopping cart icon to add to your
order.
Q2. My engine has been tuned/modified, do I need a colder/hotter
plug?
A2. You should consult your engine tuner who should be able to
advise you on the correct heat range to get the best from your
engine. As a general rule, an engine may benefit from a colder grade
of plug where modifications made have increased the temperature in
the combustion chamber (increased turbo boost, nitrous oxide use,
increased compression), colder plug will conduct heat away from the
firing tip more quickly and thus help reduce detonation/plug damage.
Q3. My vehicle has been modified to run LPG (liquid propane gas) or
dual fuel, do I need to change my spark plugs to allow for this?
A3. Generally speaking no. Plugs may not last quite as long as with
a standard petrol engine and the ignition system may have a harder
time generating a spark. The denser charge in the combustion chamber
means a higher voltage is required to jump the gap. For this reason
it may help to reduce the spark plug gap by 0.2mm. If spark plugs
become prone to overheating then it may be necessary to replace with
plugs one grade colder.
Q4. Will I get a noticeable power increase if I replace my standard
plugs with Iridium plugs?
A4. Increases are dependant on current plugs, number of cylinders,
cylinder capacity and a host of other details. The biggest increases
seem to be from large engined vehicles with a large number of
cylinders (eg 3.0L V6 and above). Having said that, any improvement
on a small engined vehicle will be more noticeable. Please refer to
our Iridium spark plugs page for further information. If you are
currently using very old/worn or incorrect spark plugs then
replacing with a new set will almost always produce a noticeable
increase in performance.
Q5. Which Iridium plugs are better? NGK Iridium IX or Denso Iridium
Power?
A5. That really depends on what you want from your plugs. Denso's
Iridium Power reputedly offer the best performance but have a
shorter service life than NGK's Iridium IX. Please consult our about
Iridium spark plugs page for a more detailed comparison.
Q6. How long should my spark plugs last?
A6. That is dependant on the application and condition of the
engine. High revving engines, driven hard, (eg motorcycles) will
wear plugs much more quickly than a large engined car which is used
for cruising. Standard copper plugs usually have an estimated
service life of 10,000 to 20,000 miles depending upon design and
application, Denso recommend changing their Iridium plugs after
30,000 miles, NGK's Iridium IX may last up to 60,000 miles in a
standard use car engine. Double platinum types may last up 60,000
miles and some NGK and Denso OEM Iridium types may last up to
120,000 miles. The plugs optimum performance level is passed a long
time before these intervals so we would recommend changing plugs
regularly as a matter of course. An engine, ignition or carburation/injection
fault or poor adjustment may cause premature wear and/or failure.
Q7. Can you send me a catalogue/patch/promotional item from
NGK/Denso/Champion
A7. Generally speaking, no. We only carry catalogues for our own
reference and we do not stock promotional items as a rule. Please
feel free to request stickers when placing an order, if any are
available then we may be able to help. Otherwise, you will need to
make contact with NGK/Denso/Champion yourself. We are not at liberty
to disclose any contact details for these companies.
Q8. Why do some spark plugs have multiple ground electrodes?
A8. This is an attempt by the manufacturers to increase the service
life of the spark plug. The ground electrodes can wear down rapidly
in some engines. Tiny particles of metal are removed from the ground
electrode each time the plug fires hence they gradually wear away.
There is a misconception that a multi ground plug will produce
mutiple sparks - this is not true, only the nearest electrode to the
centre (i.e. currenty the longest) will spark, as that becomes worn,
another electrode will become the longest and replace it as the
sparking electrode.
Q9. Do my multi ground electrode plug outperform single ground
plugs?
A9. In most cases, no. The additional electrodes disturb the flow of
gases around the spark plug tip and if anything performance is
reduced. In addition, for high performance applications the
additional metal within the combustion chamber will retain more heat
and may be more prone to detonation/pre ignition.
Q10. Can I replace my multi ground plugs with a single ground
Iridium plug?
A10. Yes - providing a suitably dimensioned Iridium replacement is
available.
Q11. What do the different letters and numbers mean in my spark
plugs part number?
A11. Please refer to the manufacturers symbol code for NGK, Champion
or Denso on our technical home page.
Q12. Why isn't my vehicle listed in your application guides? How can
I find what plugs my vehicle should use?
A12. Our application guides refer only to official UK imported
vehicles, we have very limited access to limited data for vehicles
which were manufactured for use in other countries. We can often
help identify suitable parts for 'grey imports'. We also have a
large list of vehicle specific links on our links page , many of
these websites will have a user group or forum where you can post
your enquiries - there is usually someone able to tell you what
parts you should be using. If all else fails then a safe bet is to
check the currently installed plugs. We can usually replace these or
supply a suitable equivalent.
Q13. What should my spark plug gap be set to?
A13. Most plugs are now preset at the factory and shouldn't need to
be adjusted. Please refer to your owners handbook/manual for the
correct gap setting. Our part finder application guides will also
display recommended gap settings. If you do not have the data
available then please refer to the point of sale where you purchased
your spark plugs. We will always check plug gap setting data for our
customers.
Q14. Should I regap my Iridium spark plugs?
A14. In most circumstances, no. The nature of Iridium spark plugs
means that they are able to utilise a larger gap setting while
actually requiring less voltage and straining the ignition system
less. If you *have* to regap Iridium spark plugs (e.g if misfire
occurs due to gap being too large) then do so with extreme care. Do
not use a slide type gapping tool or put pressure on the brittle
centre electrode in any way as it may become damaged.
Q15. How do I regap my spark plugs?
A15. To open the gap, carefully use a pair of fine nosed pliers or a
specialist gapping tool (not slide type for Iridium or other fine
wire types) to bend the ground electrode outwards, away from the
centre electrode. Take care not to contact the porcelain insulator
or the centre electrode as they can be easily damaged. Use a feeler
guage to check for the correct gap size - it should be a light
sliding fit. To close the gap, tap the ground electrode gently on a
hard surface and then open the gap to the required setting using the
method described above.
Q16. What is the correct torque setting for my engine/spark plugs?
A16. Please refer to our torque reference page for details, noting
whether you have an aluminium or iron cylinder head.
Q17. Are there any other factors which may affect which heat range
plug I should use?
A17. Yes, most important are atmospheric conditions/altitude (high
altitude means less oxygen and colder running, warmer plugs needed -
low altitude is vice versa), grade of fuel used (lower RON (research
octane number) means colder plugs are necessary to prevent
detonation/pre ignition. USA has low RON fuel, Japan has high RON
and UK is in between), driving style is also important - USA has
slow roads and low speed limits meaning hotter plugs are needed,
Germany has the fastest roads and sometimes no speed limit meaning
cold plugs are needed, UK is in between USA and Germany.
Q18. Can you tell me which NGK, Champion and Denso plugs are
suitable for my car?
A18. Please use the application lookup guides on our homepage to
obtain recommended NGK part information, if you need Denso and
Champion equivalents please use the manufacturer cross reference
tables or use our partsearch to locate your NGK part and then
continue to the cross reference information for that part. There are
often many plugs of varying levels of performance so for us to list
all parts available for your vehicle is usually impractical.
Q19. Can you supply a 'resistorless' equivalent part for use with
Nitrous Oxide?
There is usually a resistorless equivalent to standard resistorised
plugs. Our recommendation though, is to upgrade to an Iridium plug.
Since the reasoning behind use of a non resistor plug is the lower
voltage requirement, allowing the plug to fire under extreme
combustion conditions, an Iridium plug will provide this feature as
well as improving firing characteristics. Manufacturers strongly
recommend using only a resistorised plug where specified due to the
possibility of high tension circuit 'electrical noise' interfering
with on board computerised engine management and saftey systems.
Please refer to our nitrous oxide spark plugs page for further
information.
Q20. What sparkplugs do I need for a Mazda RX7?
Most models use a standard plug configuration which can be found
within the application guides on our homepage . The later twin turbo
model uses 2xBUR9EQP and 2xBUR7EQP and it's vitally important that
they are fitted the correct way around. If you are at all unsure
then you should use BUR9EQP in all four chambers - this should not
adversely affect performance.
Q21. What is the difference between the ISO and JIS standards? (BCPR
and BKR or IK and IQ etc)
JIS is the 'Japanese Industrial Standard' and specifies the height
of the spark plug from the gasket or tapered seat of the sparkplug
to the top of the terminal nut (or threaded terminal) as 53mm. ISO
is the 'International Standards Organisation' standard for spark
plug height and is 2.5mm shorter than the JIS standard at 50.5mm.
While the small difference in height will not affect most vehicles
(ISO and JIS types can often be interchanged), some vehicles
(particularly with direct fire ignition or specially fitted plug
caps) MUST use the correct plug standard or a bad contact between
plug and cap may be result. See diagram Common ISO type plugs are
NGK BKR, Denso K or IK and Champion C or RC. Common JIS types are
NGK BCP, Denso Q or IQ.
Q22. Why haven't you answered my enquiry?
Whilst we always try to answer genuine enquiries in a timely
fashion, there are instances where this may no be the case.
Email is not 100% reliable, there is no guarantee that we have
received your email just because you have sent it, please try
sending again if you do not receive a reply within 48 hours.
You may have supplied an incorrect email address (common!), check
the settings in your email program - particularly the 'reply
address' field.
There may be a problem with our/your mail delivery service.
We may have considered you were asking us for information for your
own commercial gain or be in competition with us in some way.
Some requests for quotation from certain nations are ignored as they
are invariably attempted fraud.
Were you polite in your request for assistance? We are under no
obligation to provide any help or assistance but under most
circumstances are happy to do so. |
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