so my lsvtec lost a bunch of compression in the #1 cylinder and started loosing oil. here are the plugs in order from 1,2,3,4 from top to bottom. motor was actually running rich, wideband readings were high 13s cruising and mid 12s wot

might rip the motor apart over christmas, just trying to see what your thoughts are so i can take corrective action for the next build

 

that doesnt seem like mid 12 wot to me tbf. I bet someone more experienced will chime in though

 

#3 porcelain looks to have a different color tint to it and the plug base looks a good bit darker. That's about all I can tell from that angle and focus.

Needless to say, low compression and using oil can only be a couple things.

 

afr was verified by multiple calibrated widebands. additionally, the motor in there now has plugs that look great/appropriate for the wideband readings. the #3 had an enrichment of 2 in the neptune settings

the exhaust valves are all white and evenly colored, but egt never saw above 700c

i was thinking that coolant was entering the cylinders and washing some of the carbon off the basering...

 

took it apart today. there was a fair amount of milky **** in the oil pan im assuming was coolant and oil mixing.

here is the head, cyl 1 at the top.


the #1 cyl intake side. all cyls have some of these marks at the top, they just barely catch the fingernail if at all. the pistons have some matching scratches between the top of the piston and the top ring. none of the rings were scored up on the edges, and none of the ringlands were broken or cracked


i found a few of these flakes in the block. none of the bearings were worn through the silver coating so im not sure where this came from. disgregard the sharpie arrow, the block had a spun rod before i bought it, but it was machined since and im using a different crank and rods


another look, intake side cyls 2 and 3. none of the cyls had vertical scoring that caught my fingernail and ran the entire length of the bore


exhaust side #1 cyl before i cleaned it. i noticed the clean spot up top where there is usually some carbon built up

 

I've seen those marks before on boosted stock piston engines when the ring lands break. They push out with cylinder pressure just like the rings and the sharp edges cause the score marks. Since it's already apart pull the pistons out and see what's going on.

 

here is the piston in the #1 cyl that had the low comp and most marking.
intake side


exhaust side






piston was removed and i just wiped it quick with a shop towel/brake cleaner.
rings were clocked to oem positions upon assembly 12k miles ago. they rotated when i cleaned the piston.
im just happy to have a camera that works decent since i got a new phone