I don't know what planet you came from, but I've lived in the tuner world with car after car for most of my adult life. Copper plugs have always been considered best for performance. The only reason you go to platinum is for a much longer change interval.
No, the NGK or KLG platinum or Iridium plugs have a copper core. The Iridium plugs -are- the "hot setup" for many cars, including Hondas, Mazdas (esp. the RX-7), and Nissans. Yes, they do last longer, but they also work better. Probably because they stay sharp longer (sharp edges produce higher electric fields, which spark over easier). Oh, and I'm from the planet Earth.
The platinum plating reduces the arc strength with everything else being equal. The point being is you never put platinums in a car that was designed for coppers unless you also upgrade the coil packs to compensate for the reduced spark strength.
From the standpoint of conductivity, copper is better than iridium, and way better than platinum. These are the conductivity figures in the elemental state: Cu 0.596 10^6 /cm ohm Ir 0.197 10^6 /cm ohm Pt 0.0966 10^6 /cm ohm Of course conductivity is only a small part of the total picture. Given the small thickness of the plating, the difference in conductivity will have little influence over the spark. The bigger issue is the geometry of the electrodes. Plain copper will wear away very quickly, quickly nullifying any advantage. Platinum will hold its shape longer, but iridium will outlast any other element. Tom
PFFT, who needs platinum or iridium when you can have quad pumped superconducting supercapactive forced induction, anti graviton, triple phase cooled flux capacitor laser plugs? It gets me over NINE THOUSAND miles per gallon of antimatter.
Bosch spark plugs are the worst. Anyone who sings there praises are on there first set and after about 3,000 miles will be pulling them out because the motor will run really bad. They suck in general. Don't believe me pull one out after 1000 miles and look at the electrode. Pretty common knowledge and David Beale is correct. NGK's are the best.
I agree the Bosch plugs had gas seal problem a few years ago. After a few thousand miles. it is leaking compressed air through the porcelain stem and causing compression lost and poor performance. You will notice a brown coloring on the stem indicating hot gas has leaked. I hope Bosch has fixed this problem.
Does it really matter what the conductivity figures for those 3 elements are when the biggest resistance to jump is the fuel/air mix? I think a spark plugs which changes it's gap less over time is more preferable than a plug which has a slightly better conductivity, since the initial resistance before the spark bridges the gap is pretty darn high. Thomas
That was my point. If you read my last paragraph, that is exactly what I said. The geometry of the electrodes, including the gap, is the biggest factor. Tom
Prius does come in with NGK Iridium as stock plugs...is it correct? (Or at least I saw it somewhere saying it's already with Iridium, for longer maintenance interval.)
Great, so we don't need to do anything til the expiration of these 'stock' Ir plugs then. I remember there's a fictional element called "Unobtainium" from the movie 'CORE'....that material has super-conductivity under extreme heat, probably that's what we're looking for as ideal plug material.
Many owners suggest removing and inspecting the plugs at around 40,000 miles. This gives you a chance to coat the plug threads with an anti-seize compound. Otherwise, after 100,000 miles, you may not be able to remove the plugs for replacement. Tom
Hi All, The copper in the plug is not for its electrical conductivity, but its thermal conductivity. I am no expert, just remember this from when they first came out, and I put them in my Opel Manta. By using the higher conductivty metal, they were able to design a plug with a broader temperature range.
The platinum and iridium plugs are almost all copper, with only a thin plating of the expensive metal. As for the advantages of copper's heat conductivity, I imagine the main conductivity advantage was that of removing money from customer's wallets and conducting it into the bank accounts of spark plug manufacturers. Tom
And pray tell, what is the model number of these power engorged plugs? (Did the OP mention he was headed downhill?) Genoz, you don't need it, you gots too many toys as it is. :-P ZC1