My guess is broken cyl.head gasket and some water..... What do u think..??
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Think ya broke it

YES...I think its broken..

How did you manage that?

I think this one might be beyond instant gasket and rad weld.

Bust without a doubt

Pourosity and steam pressure would be my guess.

What made you notice this?

Biggest bit of porosity I have ever seen

It's either that, worms or a Magnum45.

Think I'll stick with my first guess

Any shots of the block?

Did it break when you were taking it off or were you taking it off because it was broken?

Guess is....gasket started going between those 2 cylinders.
The gasses have eaten their way through
I would hazard a guess that the gasket had gone a while ago.
Check the block face to make sure it hasn't eaten its way to that.
Seen this a few times on ally heads.
HTH Fozzie

sorry mate I'm half pissed but did you notice THERE@S A HOLE EXTRA HOLE IN IT

While one pot seems to be blackened, there doesn't appear to be any staining to the surface of the hole. It looks like fractured metal rather than burnt.

Mmm I'm sober now and the first thing that springs to mind is did you find the bit thats missing. Could the gasket have gone allowing copious amounts of water into one of the cylinders which then caused that cylinder to hydraulic and burst the head. If so and you haven't found the bit it could be lurking in the water jacket waiting to cause more probs.
As a previous post said the R/H pot is blacker and sooty whereas the L/H one does appear to be cleaner and possibly has been the start of the problem. All IMCO of course and just a theory.

It broke down when my brother was testing the car.. There was some overheating problems during race season, so I guess thats when gasket has gone little broken.. But no harm done cause racing season was allready finished Those engines are cheap so no big financial loss