So I've seen a lot of talk on here about cracked plugs caused by increased boost conditions. There seems to be some debate with regard to whether colder plugs (HKS) are needed, or our stock plugs can be used as long as they've been re-gapped.
What I'm curious about is the science here. Why do plugs crack when they misfire/blowout? Is there any advantage to using a colder plug as long as we aren't increasing boost beyond what most of the piggybacks are pushing?
That's a good start.. Based on what I read there, it is sounding like our plugs are being cracked in part because of their heat range.. Which would lead me to believe that our stock plugs regapped aren't adequate for a tuned set-up.
I don't want to jump to conclusions though.. I've read that plugs that are too cold don't last as long and foul much more easily. Not good, because it looks like a PITA to change out plugs - not to mention expensive with HKS costing $23-$25 a pop.
Hopefully some of those big brained guys can drop in and set me straight.
They are probably cracking due to excessive pre-ignition and/or detonation. Most likely not an issue on the stock car, but much more likely to be seen on chipped cars with less margin for unfavorable conditions or on cars with an improper/poor tune. Changing the heat range is making pre-ignition / detonation less likely, which would then prevent the new plugs from cracking.
