What you thing about this spark plug? came from cylinder 1

 

looks like you need to rip the motor apart. no joke. either there is something bouncing around in your cylinder, or the rod bearing is so smoked that the piston is getting too high and hitting the plug.

 

For shure something went inside into cyl #1 combustion chamber and fucked that spark plug, also a piece of porcelain are inside. Compression went from 130 to 100psi in that cylinder, so i think also have a leaky valve problem or something related because the failure happens when i was tuning WOT around 7300rpm, maybe a valve float related problem. Im going to discard any rod bearing damage because is a fresh vitara / hbeam build and theres any knock. Tomorrow im going to remove the head and see what happens there.

 

fresh build means absolutely nothing. do not rule out bottom end issues. especially now. because whatever damaged that plug almost definitely destroyed the piston too. and when stuff does go crunch, not only does it destroy the piston, but it also damages the bearings pretty much instantly. so even if this damage wasn't caused by bottom end damage, whatever caused the damage to that plug definitely damaged the bottom end.

I still say bottom end damage is the cause. because the only other thing that can do that besides external debris getting sucked into the motor is either the porcelin from the plug breaking off, or a piece of valve broke off. the way the porcelin is broken off though is consistent with the ground strap smashing into it. so I doubt the porcelin is the cause. and if a chunk of valve broke off, your compression would be much lower than 100psi. so I still say something in the bottom end let go and allowed the piston to come up too high and hit the plug. which is also pretty consistent with the color too, showing entirely too much heat, probably caused by detonation, due to piston rising too far.

 

I remove the head and didn´t found anything inside, but found this small pieces of metal above the valves on the intake, for shure one of those pieces came into the chamber, fucked everything then was dropped to the exhaust together with the piece of insulator.

Fortunately piston is fine, only seems scratched everywhere but not broken. Today i will take the head to check to machine shop, i hope it´s just a valve problem that has reduced the compresion

 

No, sorry. That piston is F'd. What are those pieces? You need to figure out where they came from. What does the combustion chamber look like?

 

New pistons came rough as factory spec, this piston only looks more rough than normal but not broken nowhere. Combustion chamber also looks a bit rough but less than piston.

 

Closer look

 

Looks like a custom shot-peen, lol.

 

Actually looks like a sandblasted piston

 

Here is the comparisson new vs scratched

 

Wow that sucks. I wouldn't be comfortable running a damaged piston like that. How are your cylinder walls looking?

 

Very good question

Machine shop guy says 2 valves was damaged, maybe 3, so for shure that was the reason for compression goes from 130 to 100psi, and i don´t think cylinder walls was damaged because i don´t see any compression gases exit from valve cover breather. When cylinder wall, piston or rings have damage compression decreases way far (my previous experience)

 

It's not the rough surface why people are saying that piston is toast, it's the deep gouges on the perimeter. Those are more than scratches, those are gouges and that piston should not be run. Do what you will, it's not my engine lol but I can all but guarantee you future problems if you run that piston all scored up that way. Just grab a new slug, do a quick check on the cylinder walls and know that it's handled right when you put it back together rather than taking a gamble. Why risk future headaches? That's just my opinion though.

 

Agree. That piston is hammered. All of that changes the material properties of the aluminum in on that piston too. I would imagine that the rod bearing and wrist pin got the crap hammered out of them in the process. There's absolutely no good reason to run that thing again.