KSira

During mapping yesterday my newly built 3.0 16V turbo developed a massive wite cloud after boots. Pulled the head today to replace what i thought to be the head gasket. What i found was a very depressing. Ally 4 cylinders are scored badly. My engine builder claims it happened during mapping. Please have a look at the picture and give me your thoughts.

86 951 Driver

Were you running lean or getting a lot of knock while tuning it?

jc in rb

Yikes !

Ivan Arzola

PM sent

lart951

Tell us more about the built, what pistons and rods where you using?

KSira

After a closer look, there seems to have been a lot of knock

KSira

Its a S2 engine (16V) with H-rods, and Wössner pistons from LR. 8.5:1 compression. Stock head, stock cams, custom intake. S2 header with turbo x-over flange and lager x over pip. Precision 6266 Turbo.

Fluidplay

whoa..were the pistons new and how long were you running it? Seems like a lot of carbon build up and those pistons which would be more indicative of running rich

KSira

Newly built. Never driven. Straight from the trailer and to the dyno.

PF

Maybe a stupid question but are the pistons alusil compatible?

Regards
Peder

86 951 Driver

What weight oil? It could have been so rich that the oil washed away

Voith

****.. Looks like aluminum to aluminum contact.

gpr8er

+1
holy crap!

Dougs951S

+2, the pistons definitely made love to the cylinder walls and those pistons are absolutely, completely filthy for being new. My factory pistons that have never been out of the block are not that dirty. Sorry to hear.

Tom M'Guinn

Ouch and sorry! The Mahle piston were made with an iron coating material to run in the alusil. People have had some success running pistons without the factory-style iron based coating, but I've always considered it a gamble. What rings and what piston to wall clearance were you running? Could be a combo of things gone wrong -- pistons too tight, terrible tune, risky piston choice. Very sorry.