Go with Iridium. Platnum tips are very tempermental.
Http://www.sparkplugs.com (a forum sponsor) has very good prices.
Spark Plug Quiz:
1. What are the 9 product brands carried by SparkPlugs.com?
K&N, Autolite, Denso, KYB, NGK, Champion, Splitfire, AFE, and Michell1 Manuals
AFX Air/Fuel Ratio Monitors are a product made by NGK
2. How many of those are spark plug manufacturers?
5
Autolite, Denso, NGK, Champion, Splitfire
3. What are the three precious metals premium spark plugs are made out of?
Gold Palladium, Platinum, Iridium
4. Are standard spark plugs made with copper or nickel?
Nickel
All spark plugs (iridium, platinum, standard, etc.) have a copper core running through the center. When we're talking about plug types or metal types (platinum, iridium, nickel) we're referring to the material the electrodes are made of. Copper is too soft to use on any exposed part of the plug,
so the electrodes on standard spark plugs are made with nickel. No one understands why standard plugs are referred to as "copper plugs" - this designation is inaccurate.
5. What does RFI stand for, and how do you prevent it?
radio frequency interference - and you can prevent it by placing a resistor within the spark plug.
6. Can Platinum plugs be used with nitrous?
No. There have been instances where the platinum tip has lost its bond to either the center or the ground electrode when used with nitrous.
7. Can Iridium plugs be used with nitrous?
Yes, according to the techs, there have been no reported problems with using iridium plugs with nitrous (or a blown alcohol
motor.)
8. What are 5 types of modifications that may make it necessary to change your spark plug heat range?
If you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate
racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug.
9. What is the heat range vs. hp increase rule of thumb?
A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase.
The most accurate rule to go by would be one heat range colder for every 75-100hp you increase, as some mods do not increase horsepower, and therefore do not neccesitate a change in heat range.
10. Is it better to have too hot or too cold a plug? Why?
When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage
11. Do “fine wire plugs” refer to the ground electrode or center electrode?
Center Electrode
There are many variations to the center electrodes and ground electrodes that come under a variety of names. Specialized center electrodes may be called Fine wire, tapered point, ultra-fine electrode, taper cut electrode, necked down electrode, v-power electrode. Specialized ground electrodes may be called V-trimmed, trapezoid cut, cut back ground, fine wire ground, wedge shaped ground, inverted v-tip, tapered cut, trimmed side electrode, angled ground strap, u-groove. The ground electrode features add slight benefits to the plug, however, the family of fine wire center electrodes bring great improvements and the term "fine wire plugs" refers to plugs with a fine wire center electrode.
12. What are two benefits of fine wire plugs?
A spark plug with fine wire electrodes will perform better than a traditional plug. First, because the smaller center electrode requires less voltage to jump the gap. This means fewer misfires, which should be seen in higher mileage and more horsepower. Second, the smaller center electrode reduces quenching.
13. What are the two precious metals used on fine wire plugs?
Platinum and Iridium
The smaller center electrodes require exotic metals such as platinum or iridium so they can still maintain (and sometimes surpass) the longevity of a traditional spark plug.
14. How is iridium superior to platinum?
Iridium is a precious metal that is 6 times harder and 8 times stronger than platinum. It has a 1200 degree higher melting point than platinum and conducts electricity better.
15. Why is iridium used on fine wire plugs?
The strength, hardness and high melting point of iridium makes it very well suited for a fine wire plug.
16. Which plug manufacturer makes the thinnest fine wire iridium center electrode?
Denso
Standard spark plugs have a 2.0mm-2.5mm center electrode. NGK and Champion's iridium plugs have a .7mm and Autolite's iridium-enhanced (not considered a true iridium plug) is .6mm and Denso's is .4mm.
17. Should Iridium plugs be gapped?
No, but yes.
The manufacturers say No. Most people don't know how to properly gap a spark plug, and the center electrode on fine wire plugs can easily snap if mishandled. Manufacturers will not warranty spark plugs that have been broken while gapping. That being said: spark plugs will run at their optimum performance if they are gapped properly. This is a general rule no matter what type of spark plugs you use. I personally wouldn't pay the extra money for iridium plugs and not do everything i can to get all the benefits they can offer. Therefore, if you decide to gap your iridium plugs, we strongly recommend using the gapping instructions on our site. By following these proper gapping instructions, you should be able to gap your plugs, getting the most benefit from them, without breaking them.
18. How long do iridium plugs last?
40,000 - 80,000 miles
A traditional iridium plug such as a Denso IK20 or NGK ZFR6FIX-11 both have iridium center electrodes, however the ground electrodes are the traditional nickel construction. The ground electrode will wear out first. The manufacturers are saying 40,000 to 60,000miles on iridium plugs. But they have to temper their projections as driving conditions and motor modifications differ. Typically we have found you can expect 60,000 to 80,000 miles on an unaltered motor.
Both Denso iridium racing plug and some NGK Iridium racing plugs have iridium center and a platinum ground electrodes. If installed to a regular
engine they would likely last longer than most people keep their car (barring any motor problems that can cause premature plug death). But, these usually come in heat ranges too cold for an unaltered motor and are usually used in racing applications where all bets are off.
For the traditional automotive market, the longest lasting plugs are the NGK "IFR" series and the Denso "SK" series. These have Iridium center and platinum tipped ground electrodes, however these are extremely limited in application as they only manufactured these in a couple of heat range configurations.
19. Why should I always check the gap before I install new plugs?
Many plugs are pre-gapped for their most popular applications, however, the gap can be altered if the plug is dropped or mishandled in packing/shipping.
Therefore even if the plugs are supposedly preset for your motor, it is always wise to check the gap on each plug prior to installing.
20. How can I find the proper gap for my motor?
If you use the application search and it shows the spark plugs for you motor, the gap setting for your motor will also be displayed (if it is available). If it is not displayed, then we don’t have that data. Please consult your owners’ manual or contact your
dealer.
21. What is the maximum I can open or close the gap?
Manufacturers don't recommend adjusting the spark plug gap < or > .008". The reason for this is the ground electrode and center electrode won't line up properly, hindering spark plug performance.
22. How do I properly gap a plug?
To widen the gap, do so with a tool that only pulls back on the ground electrode without touching the center electrode or the porcelain. To close the gap on a plug, gently tap the plug, electrode first on a hard surface.
Platinum spark plugs
