mashed up ringlands.

[harvboi05]

this was why my motor was 70% low on compression in this cylinder. compression was 50% low on the neighbor cylinder. i cant explain why, but i have the feeling it was somehow related to a $1.29 checkvalve that i put in the valve cover line on this bank to keep from pressuring the crankcase, but also served a dual purpose as a deadhead. the other bank with a normal vent into the intake was perfect. the calibration is pretty solid, safe afrs and timing. this is cylinder 6, 7 was damaged too but not as badly. oh well. just gives you an idea of what cylinder pressure does to our stock pistons.

forged goodies are on the way, and so is a 2.9" pulley.

 

[harvboi05]

this could have been a pre-existing issue but i never did a compression test before i put the blower on. oops.

 

[98 Saleen Cobra]

meh I say JB weld it and run it lol!!

 

[CJK440]

I'm not sure how anything related to the cam cover breather/pcv system could cause that.

Whats the history of the motor? Original rings or rebuilt at one point?

Factory slugs are hyperutectic which require at bigger ring gap NA, let alone under boost. Perhaps a re-ring job had too little gap or too little gap from the factory. Rings ends butt, lands pop.

 

[MKSVT]

Looks like the pistons that came out of my car.

 

[harvboi05]

stock pistons. i dont think it was rebuilt at any time. 58k miles. i think the messed up breather system increased cylinder pressure on top of what the blower was doing. i dont think its the root cause, but im sure it didnt help.

 

[harvboi05]

I'm not sure how anything related to the cam cover breather/pcv system could cause that.

Whats the history of the motor? Original rings or rebuilt at one point?

Factory slugs are hyperutectic which require at bigger ring gap NA, let alone under boost. Perhaps a re-ring job had too little gap or too little gap from the factory. Rings ends butt, lands pop.

ill check the ring gap tonight.. never even thought of that.

 

[mwolson]

I thought one of the first things to break with detonation are the ring lands...

 

[harvboi05]

i cant find any evidence of the detonation, other than the destroyed piston ha. id assume the damage would be more widespread if it were legitmate detonation. thats why i was leaning towards mechanical failure.

tune has safe afrs/timing. just too much cylinder pressure? idk. all opinions welcomed.

 

[mwolson]

Hypereutectic pistons aren't known for their strength...

 

[harvboi05]

yeah i know the stockers suck. but im more or less trying to find out if this was tuning issue, a mechanical failure or a combination of both. ill think ill stop worrying about it and just have someone else tune it so i dont stress out over it.

cjk! following youre lead.. here are pics of the rings:

undamaged .019:

damaged .006:

plot thickens!