Iridium plugs

[Norbie]

NA engines are a very different kettle of fish. Iridium/platinum plugs give problems when running high-ish boost on a 2JZ, but for a NA 2JZ they work great.

[Draven]

DT: I'm gapped down to .8, and my ignition is breaking down at 18psi.

justen - get yourself a real ignition system you can transfer to the new engine remote coil packs etc

[takai]

I have issues with Iridiums/Platinums on the race engine, and thats NA. But i digress, i was also having issues with Platinums on the 4AGZE, so im back to Coppers for everything now. Although I might give them a go on the 2JZGE...

The race engine runs 0.8 gap and quad coils, and is reliable up to 9500rpm sofar.

[Camryman]

My understanding of Iridium plugs is that they are longer lasting in a boosted engine. Can't remember why though.

[Dieseltrain]

My understanding of Iridium plugs is that they are longer lasting in a boosted engine. Can't remember why though.

Your thinking of Platinums

[JustCallMeOrlando]

Nope, iridiums have a longer life also. Not as long as a platinum, but orders of magnitude more than standard jobbies. It's due to the alloy itself being more tolerant to the conditions inside an engine.

[Camryman]

If Denso's website is to be believed, Iridium is 6 six harder, 8 times stronger than platinum.

I think one advantage they are touting is that because of the small electrode, a smaller voltage can be used. I think that means ignition happens at a lower temperature so you don't get denotation problems which is why this is more suited to forced induction engines.

I do know that when they first came out the Supra owners in the US were switching to them.

[Mr Revhead]

interesting comments....

iridiums and platimuns are supposed to last longer, with iridiums the tougher.

as oldcorollas said NGK seem to be the best, but id rate Denso right with them
im very interested in those that back champions.... they are well known to be crap!
we will not fit them to a car serviced here

[oldcorollas]

platinum and iridium are not so different in many ways, but iridium is harder (as mentioned)
but, both should be very similar in terms of spark erosion, and corrosion

the temp of the spark? once ignition occurs, the detonation or not is a fucntion of the mixture and its conditions.. the actual temp of the spark is more a function of the coil/leads than the plug itself...

so the difference between the plugs i think is geometry and materials..
the idea is to have a more open access to the mixture from the spark.
to be able to do this, you need smaller electrodes.
smaller electrodes should also stay cleaner as the spark always comes from the same spot, so should be more reliable over time,
to make smaller electrodes, with more sparks from same spot, you need a much more spark erosion and corrosion resistant material, ie platinum.
iridium is much cheaper than platinum, and has similar erosion/corrosion properties, so that is why it was used...



i'm curious to know the mechanism of why the Pt/Ir plugs are not as good for high boost.. ie, spark "blow out", different temp characteristics of the tips (Pt and Ir have (iirc) lower thermal conductivity than the copper based plugs) etc...

[JustenGT8]

im very interested in those that back champions.... they are well known to be crap!
we will not fit them to a car serviced here

as stated, they have come out on top of every plug test comparison i've seen ? Differences are always minimal and they do appear to fould easy but they are cheap so just replace.

[oldcorollas]

fouling is just a temp range issue... between a range of actual temperatures, the gunk should not build up on the plug.. it should burn off... too high or too low and the plug will foul and fail..
the different design of the plugs will mean different parts of the plugs maintain different temps...
again, it would be interesting to see a bit of a study on this stuff

[Mr Revhead]

got any links to any tests?
do those tests include running them in a car for a period of time more than a coupla days?
or are they simple bench top tests?

[takai]

got any links to any tests?
do those tests include running them in a car for a period of time more than a coupla days?
or are they simple bench top tests?

Well as for my experience, i would have to clean out the Platinums after each and every race and then usually replace them after the round compared to the Coppers which are fine through the entire round and are replaced after each round only because they are so cheap.

[JustenGT8]

got any links to any tests?
do those tests include running them in a car for a period of time more than a coupla days?
or are they simple bench top tests?

rolling road dyno test done by a coupla mags.....no links as such.

currently running champion golds as the platniums developed a miss on 17psi....no issues but looking at a few more psi so want to stretch the stock ignition as far as possible. Heard some were having succes with narrow electrode iridiums? had to check it out. All looks too inconclusive at present

[manny]

My 2 cents...

Below is my dyno readout for my 1JZ-GTE Soarer back in 2004 with back to back Dyno runs - same Power FC tune, same boost, same tank of fuel, same day/temps, same dyno, same operator in front of dozens of watchful sceptics at a ALSC Soarer dyno day in Castle Hill within half an hour of each other at warm engine operating temps and comparing less than 50km old NGK BKR7E copper plugs versus some new Denso Iridium IK22 plugs - same heat range and both gapped to 0.8mm and run off a HKS CDI DLI ignition amplifier.

I wouldn't have believed it if it hadn't happened before my own eyes.
Ignoring the extra 6rwkw peak, there were definate gains across the board but most important was the midrange improvement on the drive afterwards which was very noticeable on the road at both part and full throttle.

I found coppers resilient to fouling when the tune wasn't quite right between mods/tunes as the Iridiums would foul easily, but once the AFRs were right across the board, I've been getting about 20,000kms out of set for almost 4 years across 4x 1JZ-GTE/1.5JZ-GTE/2JZ-GTE engines.

My previous poor experiences with Platinums in my 1JZ-GTE Soarer have since led me to believe they are good only for economy as used in my stockish 1UZ-FE Soarer ; when used in a performance/boosted application for me, they broke down easily, lost tips and wore out as quick or quicker than coppers whereas in the 1UZ-FE Soarer, they've lasted over 50,000kms troublefree and without any maintenance.

IMHO, for $100 worth of plugs, it can't hurt to try it out.