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Thanks to Brad.....

Hope this answers some questions...

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)
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 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 up to 12,000 miles, Denso recommend changing their Iridium plugs after 30,000 miles, NGK's Iridium IX may last up to 30,000 miles in a motorcycle and up to 60,000 in a car. 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 fault or poor adjustment may cause premature wear and/or failure.

Q7. Can you send me a catalogue/patch/promotional item from NGK/Denso/ChampionA7. Unfortunately no. We only carry catalogues for our own reference and we receive no promotional materials. 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. 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.
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