Anybody know if Iridium spark plugs are really better than Platinum? The dude at Advance Auto parts sold me on these NGK Iridium plugs that were about 7 bucks a pop. My friend says the spark piece itself looks a little thin, but if they really are the best material on the market then I suppose it's fine. Anybody tried them??

 

I've got the Denso Iridium in my N/A and it runs perfect. $10 each.
Iridium has a melting point of almost 700ºC higher than platinum, and had the greatest potential for resistances against wear. (according to Denso research)
And 1 more thing, Denso Iridium have a copper core....

 

Ir is more dense than Pt or Cu... That's why it's thinner..

I stay with Cu, ... No better performance, only longer lasting ...

He should have sold you the Cu's since they don't last as long and maybe he could sell you something else since you'll be back there quicker with the Cu's.

 

Here is a cut and paste of the reply I gave to this question a few weeks ago...


The Denso Iridiums have a smaller Ir center electrode (.4mm) than the NGK but also have a standard (Ni) ground electrode although grooved and cost ~$12 each. (last on avg. 40-55k miles)

(Double platinum plugs last on avg. 75-100k miles)

The benefits of the Ir plug are that the element is very hard (Mohs: 6.5), has a very high melting point (2443°C), excellent electrical conductance (0.197 106/cm), and a great ablility to resist heat transfer (0.816 W/cmK). Due to these properties an Ir electrode can be much smaller than the other elements on the list, transfers electricity better than all but Cu, and resist heat transfer better than all but Pt.

Copper is a great conductor of electricity with only Ag being better, but Cu absorbs heat at a incredible rate, and has a very low melting point so Cu plugs do not last very long (10-15k miles on avg.)

Here is a table of common electrode elements
Conductance of electricity larger numbers=higher transfer, Hardness larger=harder, Thermal conductivity larger=ammount of heat it can transfer from another substance to itself

0.596 106/cm Copper Cu 29 |melting point (1084.6°C)|hardness Mohs: 3|thermal conductivity 4.01 W/cmK|(non-brittle metal)

0.197 106/cm Iridium Ir 77 |melting point (2443°C)|hardness Mohs: 6.5|thermal conductivity 0.816 W/cmK| (very brittle metal)

0.143 106/cm Nickel Ni 28 |melting point (1453°C)|hardness Mohs: 4|thermal conductivity 0.907 W/cmK| (non-brittle metal)

0.0966 106/cm Platinum Pt 78 |melting point (1772°C)|hardness Mohs: 3.5|thermal conductivity 0.716 W/cmK| (non-brittle metal)

(references: http://environmentalchemistry.com ,http://www.gordonengland.co.uk/hardness/mohs.htm, http://www.webelements.com)

 

No dyno no care ^^^

 

If that is true, then that is the next plug I'm getting. Cu core for better spark but Ir properties for longer life.