Silver Spark Plugs?

[Rambaud]

Anybody used these?

Any comments etc?

Apparently, iridium and platinum plugs are not very good for electrical nor thermal conductivity but are good for longevity?

[Rambaud]

No comments?

These are the plugs I saw :

http://www.nology.com/silver.html

Snake oil?

[I-S]

Snake oil.

Iridium/Platinum/etc are just platings on a copper core. This plating is very thin (about 1/4 mm) and its conductivity, either thermal or electrical, is largely negligible to the performance of the spark plug.

The benefit of iridium and platinum is their hardness - they don't wear away with use anything like as fast as copper. The first benefit of this, and the main reason for OEM fitments of these plugs is that the service interval can be extended significantly. The second benefit is that the plug electrode can be made smaller and sharper-edged (plus remain sharper-edged over time), which reduces the spark-over voltage.

The peak current carried by a spark plug is of the order of 60mA. With the amount of metal in a spark plug electrode, the difference in conductivity between silver and copper (plated with whatever) is negligible.

As for thermal conductivity - that is specified by the heat range of the plug. Since these plugs will have to fit into existing specified heat ranges, the difference of the material is unimportant - the plug will be engineered such that the thermal conductivity is the same.

I suspect the company behind these may also be involved with hifi cables.

[Rambaud]

Thanks for that, Isaac.

Personally, I am not that interested in longevity.

I am not happy for an older (say 10 years old) car to see a garage only once per year.

So I am now off to find the cheapest NGK/Denso etc plug with the correct heat range. :)

[Patryn999]

Plus there is a resistance (usually about 5K) within the plug ceramic anyway (this drastically reduces EMI, which can cause issues with electronics). Any modern car with electronics requires the plugs (or the spark plug caps themselves) to be resistive, hell even my 1983 Townace required them. (otherwise spark interfered with OEM radio :D )

So the difference between 0.01 and 0.1 ohm is kinda negligible when you have a 5000 ohm resistance in there already (with a tolerance of probably 5%).

Only reason we have the iridium ones is to increase service life (as I-S said). Especially in engines where changing the plugs can take an hour+...