HG failures with ARP head studs, give us the low down.

[subsonic]

I know I have been seeing quite a few posts about HG failures / Coolant being pressurized even with the ARP 12mm head studs.  
I know Andy2 has had these issues, but he is way out there on the extreme  edge with HUGE boost.  
Who else has had these issues?
Does there seam to be a common point where this is happening, like 30 psi and beyond?
Is this happening with the hot 1.9's as well as the hybrid 1.6/1.9?
Could those of you who have had this problem list what your setup is like so we can compare against others to see where weak spots may be?
Is this just a result of big pressure, or do other factors like high EGT's, block flex etc combine to weaken the setup?
Andy2, during your build up, how high could you go with the standard pre-combustion chamber (before you went to the bigger size) and keep it together?
Just looking for a little brainstorming to see if any common indicators show up.  Of course as a byproduct, I would like to know how high I can go and still be reliable.  My boss really does not want to hear about how I was late because "I blew my head gasket on the way in, but man I hit 40psi of boost on the way in, laid down some serious rubber before I  smoked a bunch of shocked drivers in sport cars, man that kicked ass!"

[rabbid79]

I've seen a lot of discussion about preparation of the head and block mating surfaces.  As far as I can remember, it seems like people aren't having them machined perfectly smooth.  From what I know about it, because the block and head are different types of metal, and therefore have different expansion rates, the smoother the surfaces between them, the better.  This allows them to expand and contract at different rates, and slide across each other.

There was a link on one of these threads to a company who built custom head gaskets.  That was their philosophy as well.  The question is, for those who are blowing head gaskets, what kind of surface preparation are they doing?

[jtanguay]

"I blew my head gasket on the way in, but man I hit 40psi of boost on the way in, laid down some serious rubber before I  smoked a bunch of shocked drivers in sport cars, man that kicked ass!"

damn... too bad i wasn't your boss...!!!  :lol:

[DVST8R]

Mark Malone had those issues as well in his franken motor, I'm sure that he or Dave @ PP can enligten you on the details of that.

His basic specs, were a GT20 48 or 50 trim, not sure which. A fresh built 1.6 TD bottom end, with a port and polished 1.9 head, HD valve springs, with pd130 intake port matched, a cast atp style exhuast manifold port matched, and ceramic coated as well, his turbine on the turbo was cermaic coated. Giles pump 9mm head with agressive camplate, and "no" rev limit.

I think Smokey Dub had issues too, but I will let him chime in, as I know non of those details.

[jtanguay]

Mark Malone had those issues as well in his franken motor, I'm sure that he or Dave @ PP can enligten you on the details of that.

His basic specs, were a GT20 48 or 50 trim, not sure which. A fresh built 1.6 TD bottom end, with a port and polished 1.9 head, HD valve springs, with pd130 intake port matched, a cast atp style exhuast manifold port matched, and ceramic coated as well, his turbine on the turbo was cermaic coated. Giles pump 9mm head with agressive camplate, and "no" rev limit.

I think Smokey Dub had issues too, but I will let him chime in, as I know non of those details.

ceramic coated turbine??? does it need to be re-balanced afterwards??? what kind of benefits other than not melting, would it have??? or is it just the housing??

[DVST8R]

Just the housing.  :wink: