Spark plugs getting smashed...wtf? (on buddy's car)

[mval123]

Here is his problem:

So I had finally found my idle gremlin by cleaning out my iacv and everything was running great. Took the car out for a spin at was boosting 10 lbs on the 2871 .86. My engine is freshly rebuilt and no major noises or anything. I drive about 10 miles around town varying my speed. Then I took it out of town. I get to a stop on a country road and turn left and get on it. The car starts to sputter and sound like a subaru. I pull over and things didn't seem right. I limped the car back home to find my #4 spark plug has 0 gap and the ceramic is broken. There is visible tiny dings all over the top of my #4 cp piston. So i replace that spark plug and oil then start the car back up. No abnormal noises again. So I go back out for a spin and everything seems fine. Same Fawking stop sign i get on it and go the other direction same thing happens but this time it's #3. I limp the car back home and find the same problem with 0 spark plug gap and tiny dings throughout the top surface area of the piston#3. Also #1,2,4 are all clean except from the previous dinging to #4.

My delima is do i replace the spark plugs again and just hope stuff is outta there or what the hell is causing this? Has anyone else had this problem? I don't want to ruin my motor by not making sure.

[S13xCrazy]

I'm no turbo pro, but do you have colder range plugs? maybe they are getting to hott and falling apart o_O?

if im wrong, ignore this. haha!

[redtop91]

Indeed. And you might want to verify that the plugs aren't being overtightened. You have one fvcked up head if the pistons are contacting your plugs.....

[S13xCrazy]

Also, make sure you find the little peices and get them the FVUCK out! They will just cause more and more havock if they stay in there.

[redtop91]

Wait a second. Do your pistons look like these to a less extreme level?

[S13xCrazy]

WTF! what in the hell caused that!?!

[redtop91]

Valve float. It will beat the f*** out of anything near the head of your motor, including plugs...

[mval123]

There is little divets on the piston (not nearly to the extreme represented in the picture though). We've been running heat range 7 (bkr7eix plugs). Would it be plausible to go colder or is it definetely beyond a plug problem? JGY did all the head work on it (3-angle, hks springs...can't remember what what else was done). Could timing be the issue also? I'm pretty sure the tune (enthalpy rom) called for timing to be set at 15 which it was, but is it possilbe in needs to be advanced/retarded a bit? Thanks for the input so far

[mval123]

Also, if the valve float was the culprit wouldn't there be smoke/running rough?

[themadscientist]

I assume your head and block were decked? Your piston probably sits perfectly flush or slightly above the deck at TDC. When you wind the motor out there is a little bit of stretch in the parts and the parts do expand when at operating temperature reducing clearances even more. Detonation will shatter a plug's ceramic but the smashed closed electrode says physical contact as do the dings in the piston. put a set of washers under the next set of plugs to pull the business end of the plug up out of the way and and see if it stops.

[r34 gtr]

Def. go with the washers. Sounds like there isnt quite enough clearance in there. Heat range 7 plugs also seem a little warm to me for the 2871. you might want to give some 6s a try (or whatev. the colder range is). I highly doubt its causing this problem but I was just under the impression one should go a step colder with a bigger turbo and more boost, even though it isnt much more.