I apologize that I don't have any literature for you to read through. It's just been my experience over time. My thought is the deterioration of the materials between the gap over time obviously. An electro-chemical reaction combined with heat I'd imagine is a factor too. The heat would soften the strap and electrode, and the fuel and spark to accelerate the degradation. I don't know how presure comes into play in creating the larger gap.

 

you said that you started misfiring after putting the Q16? are you sure its the spark plugs and not the high octane map?

 

Could be, but not likely.

I've had the plug gap grow on many turbo charged cars and without higher octane fuels; moreover I've measured the differences in gaps to only to confirm my thoughts.

 

i can confirm the gap grows on other turbo cars as well over time. this was happening on my 04 2.0 litre EDM STI and I was told its normal wear.
I think that with the EVO it is best to stick with stock plugs even with 400whp. many people have problems when they mess around with their plugs on the IX..

 

So is that IKH24 one step colder then stock or what?

 

Yes