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Old 09 Jan 2008, 03:49 pm
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Dream4 Dream4 is offline
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Default Re: Hard Misfire Under Load plugs changed

Originally Posted by Cal Cruzer View Post
Not sure where this myth about melting platinum tips got started but here is some info

Melting point of: copper - 1,984 F
platinum - 3,214 F
iridium - 4,471 F\

Search as I may over the years I have never found any difinitive data/studies indicating problems with platinum melting sooner than copper. All I have ever been able to come up with is the "my brother knows a guy who was once married to a girl whose brother's sister-in-law said her platinum plugs melted." I have come across some individual case studies that indicate smaller electrodes, (i.e. platinum and iridiam plugs) perform better. The smaller the electrode the better)Spark plug comparison - iridium vs platinum

The other side of this arguement would be on "high heat, high boost" racing engines (not really an issue with the PT GT). The platinum plug's tip, while smaller than copper, is somewhat larger than platinum which reduces it's ability to conduct heat away to prevent pre-ignition. Here is a discussion of this Spark Plugs -

General statements that "platinum plugs are bad for turbos" do not seem to be supported. The one issue that did arise years ago with iridiums that I read about was a problem early plugs had in manufacturing before they perfected a way to attach the iridium tips, and some came off. I have not read of this in many years though so I assume that issue was overcome.
I have a posted this around here several times, but can't find it right now, but your old info is still correct for the PT Turbo. But here it goes again and my information was from the engineers at the Mopar Performance hot line that is listed on every Stage 1 install sheet 888-528-HEMI (528-4346), feel free to call them they are very nice and informiative,

It is not the Platinum that melts, it is the bonding metal that welds the Platinum tip to the center electrode (they only use a very small Platinum tip), and that the 2.4 Turbo PT & SRT4 have one of the highest combustion chamber temps of any production street car (approx 1700 to 1800 degrees F), the engine is designed & calibrated to run these temps both for performance and emissions, (Yes it is a issues as the PTGT is a very high heat engine), now you can run Platinum plugs on most other factory stock turbo cars, as they do not run this hot, stock you may get away with it, but with the higher boost & temps when modified with Stage 1 & above parts (ie larger turbo, stronger WGA, boost controllers etc) the Platinum plugs come apart and will embed the Platinum tip into the top of the piston or get stuck in a valve opening causing major damage.

They are also not recommended for NO2 or any Alcohol injection, and also any of the Meth/Water Injection systems, by Spark in their FAQ section. - Spark Plug 411.

Again, if you want to use them that is up to you, But Mopar Performance highly recommends that you do not. As cheap as the recommended NGK copper 4306's are, I don't see why you would want to spend more anyway. (but that is me)
'05 GT Dream Cruiser Series 4. No.1109
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