RB26 piston crown deposits

Hi all,

Apologies if this is in the wrong place.

I borescoped my cylinders recently and discovered a kind of white/yellowish residue that looks like Lichen on a grave stone... See pics. Any idea what it is and what causes it? Slightly concerned it is running somewhat lean. Car is an R32 GTR fitted with R34 GTR stock turbos running on (at the moment..) a stock ECU.

Thanks in advance!

Nick

There seems to be some false colour there, as can be seen by the red on the bore surface, and possibly some 'bleaching' from a bright light source.

Hard to say for sure, without pulling the head, but I'd expect it to be be the normal surface deposits that build up over time on any engine.

Hi Nick

What fuel you use ?

Thanks for your replies! I am using 98/99 RON.

Do the engine has misfire or hesitate ? burn oil ? fuel additive? spark plug look ok?

Like Gord mentioned, can be normal residue and nothing to worry about the deposit