Upgrading to Platinum plugs

[NickCLotus]

Any thoughts on fitting upgraded longer-lasting spark-plugs to a Peugeot 1.6 16v TU5JP4 engine? Probably not worth the cost of going to Iridium, also had some problems with NGK Iridium, but possibly Platinum tipped ones might be better than the standard Nickel tipped ones.

Original spec for this engine is Bosch FR7ME, currently has Bosch FR8SC+ fitted, anyone know an equivalent Platinum tipped plug?

[trickywoo]

Unless they are tricky to change meaning a longer interval is beneficial I’d stick to copper.

Nothing out performers copper in terms of setting light to fuel.

[Chris32345]

trickywoo said:

Unless they are tricky to change meaning a longer interval is beneficial I’d stick to copper.

Nothing out performers copper in terms of setting light to fuel.

Iridium plugs are definitely better and more reliable then normal plugs

[trickywoo]

Chris32345 said:

Iridium plugs are definitely better and more reliable then normal plugs

They last longer but they aren’t better in any other way, especially price.

[Dogwatch]

trickywoo said:

They last longer but they aren’t better in any other way, especially price.

When you see the amount of work required simply to access the rear plugs on a transverse engined V6 or V8 then "lasting longer" is well worth it.

[Chris32345]

trickywoo said:

They last longer but they aren’t better in any other way, especially price.

But they are
They put far less stress on the rest of the ignition system due to the fact they make a spark easyer

[trickywoo]

Chris32345 said:

But they are
They put far less stress on the rest of the ignition system due to the fact they make a spark easyer

I’d like to see your workings on that given copper is much, much more conductive than iridium.

I’ve researched this and would suggest you do too before spouting what you think.

[kambites]

Chris32345 said:

trickywoo said:

They last longer but they aren’t better in any other way, especially price.

But they are
They put far less stress on the rest of the ignition system due to the fact they make a spark easyer

It depends on how they are designed. The potential required to jump the gap is determined by the width of the gap itself, the chemical makeup of the gas being jumped, and crucially the shape of the electrodes. The gaps tend to be the same and obvious the gas wont change, but Iridium is hard and ha a very high melting point so plugs can be made with pointier electrodes while maintaining a decent life span.

Of course you could make a copper plug with pointy electrodes, but it would last about a week. Or you could make an Iridium one with flat electrodes and it would last for decades.

ETA: As above though, Iridium doesn't conduct quite as well (I think it has roughly three times the resistance of copper) which gives it a disadvantage in getting the potential to the gap in the first place, but the Iridium tip tends to be very thin for this very reason.


Ultimately everything is a trade-off, but if you engineer an Iridium plug for the same lifespan as a copper one it will, from what I've seen, have a slightly lower potential requirement to generate the spark. Alternatively, you can engineer one to last a bit longer than a copper one and give it the same impedance. Or you can engineer one to last for aaages but it'll be a bit rubbish at generating a spark.

Edited by kambites on Sunday 26th May 08:40