I have a stage 2 wrx, and will need to replace my plugs, and so want to know if it makes a difference between the two brands? I plan on going one step colder again.

The center electrodes on the Densos are much finer.I got pics comparing the two.I will try to dig them up.

So the finer the better?

ya would like to know as well.

anyone?

I thought Iridium spark plugs were a maintance item, not a performance item (copper conducts better, but does not last as long)? I've even heard rumors that some tuners will not tune your car with iridiums since they are prone to det.

I thought Iridium spark plugs were a maintance item, not a performance item (copper conducts better, but does not last as long)? I've even heard rumors that some tuners will not tune your car with iridiums since they are prone to det.

I can honestly say I have NEVER heard that before. :huh:

The 4g63 Mivec motors use Iridium stock (Evo IX).

And copper is a better conducter but our coil packs were designed for the resistance of platinum plugs, and the gains are around 1-3h region from going copper and they tend to need to be replaced every 3-5K miles depending on the setup.

And OP you should not and have absolutely no reason to use 1 step colder plugs on a stage 2 setup, your only making your plugs more prone to fouling. I don't know what everyones obsession with 1 step colder is on lightly modified cars.

I would just get the oem plats in the stock heat range or coppers in the stock heat range.

I personally run the copper and change them every other oil change or 6k miles.

i ran the bkr7e for 15k miles and they were just fine

$2/ea

iridium is just a fancy way of spending $$$ foolishly

I can honestly say I have NEVER heard that before. :huh:

The 4g63 Mivec motors use Iridium stock (Evo IX).

And copper is a better conducter but our coil packs were designed for the resistance of platinum plugs, and the gains are around 1-3h region from going copper and they tend to need to be replaced every 3-5K miles depending on the setup.

And OP you should not and have absolutely no reason to use 1 step colder plugs on a stage 2 setup, your only making your plugs more prone to fouling. I don't know what everyones obsession with 1 step colder is on lightly modified cars.

Sorry about that, you are right, I'll correct that, not specifically detonation.
I think I read too much into that (as in copper spark plug electrodes melting if it gets too hot; whereas, platium and iridium have much higher melting points and will just knock).
post #4:
http://forums.nasioc.com/forums/showthread.php?t=695043&highlight=iridium+spark+plugs+tune

Denso markets the thinner iridium electrode rivet as a feature.

*none of the below quoted was from strohausii ;) *

OK so 1 tuner...and I still maintain iridium are the stock plugs on the Evo that runs 21psi stock.

If someone is having issues with the spark blowing out then they are gapping them too wide. I'll also add he specifies DENSO plugs and not all Iridium and I'd gather a large portion of people tend to run NGK anyway.

This is also in the same post thats says Stock BOV valves leak around 17-19 psi when there is no general rule for that and lots of people are fine well above 20psi.

Also I cant stress this enough.. Running stock plugs or large gap plugs on a hot setup will cost you 30-40whp. Misfire often times limits my ability to tune for power. Funny how people run stock range plugs fine on setups with 150hp over stock or more(including me at my first 20g tune) and certainly are not magically missing 30-40hp.


Lets not miss this If you have an upgraded turbo and or injectors please use NGK plugs in heat range 7 Really? So if i had my little td04 but I put some 650s in I would need 1 range colder plugs? thats funny.

Lets not also forget NGK does not list Copper plugs under their fitment guide for these motors because the coil packs in our cars are setup for higher resistance platinum type plugs not the ultra low resistance of copper which has potential for burning the pack out and has happened on more than one car although very rarely (for sure on 2.5L, I don't have a 2L so I don't know if they are different)



None of this is meant as a 'attack' on you. I'm just point out I disagree completely and there are alot of things this guy is saying that just don't make sense. Oh and that information is more than 3 years old now.

Damn, I was editing my post before you posted yours.
No offense taken, I'm glad someone can clarify.

BTW could you fix those quotes above so they are not mistaken as mine as I'd never make those kinds of claims?