What in the hell could have caused this.......??

 

mine looks the same...

 

pressure and det get a $10 circuit board componed magnefying glass from Radio Shack and see if there are pits and gouges on the ceramic isolator

 

with 110 oct. the rest look normal. About 3/4 down the track it was like I didnt have any fuel or something. started back firing and stuff. Im really concerned about this. After I changed the plugs it seemed to run alfot getter but I pulled the plugs after a day from being in and the fourth one was still a little darker.

 

Did this happen the same night you did the 115.3?

 

I did this the second time around. here are the pics in order 1-4 on the night of the race.

 

of plugs I pullede out 24 hours later. In order 1-4

 

Also on the 4th plug from the 110oct it blew part of the porclin off the inside of the plug.

 

weird.... mine did the same thing today at the track....i think its the same plugs(NGK BPR7ESS..?) 1st 2 run was ok then on the third run it started back firing at about 10 psi...took em out and it sorta looks like yours...not as bad though...i put the stock ones back in and its fine now..i'm never gonna buy those cheap as ones no more...iridium all the way...

 

Do you mean in other words it could have to much timming on the tune? Probably be safer to back it off a bit? Just wondering if this is what it sounds like to you.

 

what concerns me is the gap on cylinder 4, is that an illusion or has the ground strap bent over.
if you have made contact that is not good, read rebuild.

 

Looks to me like a detonation/heat condition, of course once it stopped firing it then got all the soot all over it.

the concussion from a detonation event, combined with a slight lean (high heat) condition is enough to cause that. You'll have to do what david@vishnu suggested, get a magnifying glass and look at the conductor, considering how deformed it appears the conductor might have melted.

Oh, and when you get a chance, if you know someone with a scope, have them scope the inside of the cylinder through the plug hole to look for obvious damage.

No idea what boost levels or tune your running, but you might have to go another step colder on your plug...

 

Good point, its possible something "Stretched" such a defect in a rod, or the rod bolts themselves started stretching (you would get a telltale engine knock in that case)

However contact would have both deformed the electrode on the plug, but likely left an imprint on the portion of the electrode that made contact, and it doesnt appear to have made contact.

Like I said in my earlier post, try to find someone with a videoscope to look inside the bore and piston surface and look for any obvious damage from contact.

 

those plugs look like they definitely melted. I took my stockers out and they are very clean.

 

do you think there is any internal damage?