acourding to the pro'* the budget way out is a ngk. the best way is Denso plugs but they are more exspensive. I will get part numbers.


Ty

A Long Time Ago...

Approximately 50 million years ago an asteroid, some 10km in diameter slammed into what is now Mexico'* Yucatan Peninsula near the town of Chicxulub. The resulting dust cloud destroyed most living things and ended the dinosaurs reign on earth. The evidence for this has been known for some time, with the deposits of Iridium-rich clay found at the boundary of Cretaceous and Tertiary deposits (known as the K/T Boundary) all over the world.

On July 2 1992, Alan R. Hildebrand of the Geological Survey of Canada presented a scientific paper to the General Assembly of the Royal Astronomical Society of Canada entitled "The Cretaceous/Tertiary Boundary Impact". Some of his findings are summarized here.

The K/T boundary layer, sometimes known as the iridium bearing clay layer, has a global distribution and consists of at least two layers of impact material.
The upper layer, known as the Fireball layer averages 3mm thickness and represents 1500 cubic kilometers of debris deposited globally with no apparent variation in thickness.
The lower layer termed the ejecta layer, averages about 2cm in thickness.

A Major Impact on Earth?

Many scientists believe that the enormous impact put enough dust into the upper atmosphere to darken and hence cool the Earth for several years. This was theorized to result in shutting off global photosynthesis, with the resulting collapse of the global food chain. As a result nothing larger than 25 kg survived the boundary.

Iridium is found all over the world in the K/T layer and is not an unknown metal (commodity), however; its ability to be used in a manufacture type environment is unique. The current products that use Iridium are cellular telephones (Motorola), sunglasses (Oakley), and now spark plugs (DENSO). The reason for only a few companies using this precious metal is its difficulty to be manipulated in a cost-effective manner.


DENSO'* experience with Iridium in the development of the complete line of original equipment platinum spark plugs helped in the development of the patented DENSO Iridium alloy, where the Iridium becomes the primary metal complimented by rhodium (Atomic Symbol: Rh) to increase oxidation wear resistance.

Q. What makes Iridium better?
A. Until recently, platinum was considered the best material to use on the top of an electrode because of its durability. However, Iridium is 6 times harder, 8 times stronger, and has a melting point 1200 degrees higher than platinum. Put that into a harsh environment such as an engine piston chamber, and you have a spark plug that can resist wear much better than platinum. Additionally, the DENSO Iridium Power alloy is so durable; it allowed our engineers to produce the world’* smallest center electrode (.4mm) which reduces the voltage requirements, concentrating its sparking power. Also, its smaller size, combined with the tapered U-Groove ground electrode, allows more room for the flame kernel to develop and produce a more efficient combustion.

Q. Why are there different heat ranges? Which one should I use?
A. Part of your spark plug’* responsibilities, in addition to firing a spark, is to remove heat from the combustion chamber. This is accomplished by channeling the heat through the insulator material and metal housing. From there, the heat is transferred to the cylinder head where the engine cooling system can go to work. A spark plug’* heat range is its ability to dissipate heat. The “colder” the plug, the more heat it can channel out of the combustion chamber. In a performance application, colder heat ranges may be necessary to handle the extreme temperatures brought on by higher compression ratios, forced induction, and high RPM’*. While “Colder” plugs may seem to be the way to go, please remember that the spark plug must achieve its “self-cleaning” temperature where it can burn off fuel and carbon deposits. Otherwise, the plug could “foul out” where it is prone to misfiring and poor acceleration. A plug that is too “hot” can overheat, also causing power loss, detonation, pre-ignition, and possible engine damage. A good, general rule of thumb is to start with the factory recommended heat range. For every 75 to 100 hp you add to your engine, you may go to the next colder step. DENSO heat ranges move up as they get colder; 16 would be our hottest Iridium Power plug, 34 would be our coldest (ranges; 16,20,22,24,27,31,34)

If you have any furthur questions you can find me at Bonneville attitude or at my E-mail domesticperformance@attbi.com

Ty