Should I be concerned?
Turbo Mini Forums

After stripping my engine to sort out an oil leak I thought I might as well remove the cylinder head just to check for signs of detonation. I've become paranoid about detonation after reading so much about it on here . I'm running half bar boost, 9.0 cr, 97 octane, omega 11cc pistons and about 18 degrees advance. To me it just looks like no4 piston has run hotter than the rest. I do plan on upgrading the radiator as it did get hot about 100 degree C.

Any thoughts?

Was there any problems with the gasket? Possibly leaking anywhere?

In the 13's at last!.. Just

What are the marks on two and three that look like pock marks ?

Given your boost and timing, unless it was running very lean I would not have expected any detonation, though.

Head gasket was ok, I've got a cometic gasket that I'm in two minds about using, if I use it I will get my cr a little lower.

The marks in the center of the piston are little raised pieces that I assume were left over from the machining process.

I think the darker colour of no4 piston is cos its got hot, I'm going to add a small radiator onto the head bypass, hopefully this helps.