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Message: [QUOTE="KCTurbos, post: 907265, member: 13852"] Here is a picture of a dead flat head, proper tq procedure, standard arp studs, OEM gaskets that started slightly leaking right after going above the 550hp mark. I would say 90% of the 6.0 population would not have noticed it leaking unless you spent hours on a dyno or drove around with a psi gauge on the coolant system. It took me many tests and tries and buying new caps and lowering the coolant level to finally put a gauge on. Even after I put the gauge on it would take me almost 20 min of 0-70 WOT runs to get the psi gauge to hit 16psi. But after taking off the heads it is pretty obvious they were leaking. It only leaked on really high PW tunes which raised the cylinder pressures slightly too high. If we went back to a lower pulse width tune it would not leak anymore. [IMG]http://i280.photobucket.com/albums/kk170/chstfish/IMG_20140130_183343_157_zps4e828eb8.jpg[/IMG] Understand for the following theories I am not talking about huge amounts. We are talking about flexing, stretching, and elasticity in very small measurements. So why leak dead center in the middle of the cylinder??? That would imply that the head flexes in between the studs/tty bolts (which makes sense). IMO the sealant around the cylinders makes the gasket thicker in that area, therefore applying slightly more PSI clamping force around the fire ring area. It will also have a certain amount of rebound/elasticity when the head flexes under high cylinder pressures. Now if the heads are dead flat it will help keep the heads from blowing under a little bit of flex. Now if they are warped I don't think it will have enough elasticity to help at all. This is also one of the reasons why I think the black onyx head gaskets sucked. They did not just have sealant around the fire ring area. They had sealant around the whole head gasket. This would not have the same affect as the Ford OEM gaskets because it would lose that little bit of higher psi clamping force around the fire ring area and that slight bit of elasticity. With 100% sealant everywhere the clamping force would once again be re distributed to all the area again. Which brings me to my next point. If the heads are flexing in between the studs then how in the world does a stronger stud stop the head from leaking? Well I think under high cylinder pressure the head will flex to a certain amount, the sealant compound around the fire ring should be the last thing touching and creating enough clamping force to keep the head gaskets from blowing. Now that head will only flex so far (it is not going to fold in half like a piece of paper) after the head can flex no more I believe it will stretch the stud ever so slightly (not to the yielding point) kind of like how you can keep torquing the studs down and stretching it. Now once your stud/tty bolt stretches even the slightest bit... YOUR HEADS BLOW and take out some of that sealant compound with it. It might just be ever so slightly leaking and not enough to build up much PSI in your coolant but IMO it will get worse over time. Also if your truck does not overheat and you don't warp the head then your head should return to its original state and stop your head gaskets from leaking once the cylinder pressures return to normal. That is another reason why I think some of these guys only see leaking gaskets under super high cylinder pressures. So you cannot stop your head from flexing but you can increase the tensile strength of your stud which with proper torquing will increase your clamping force. But how can you stop your head from flexing? Well IMO you cant... but this is why I like the idea of Oring headgaskets. This will create even more psi clamping around the fire ring where it is needed most. It will also allow for even more flexing and head stretching because now the last thing that should touch will be those metal orings. It is just one more safety net IMO. PS... I would love to hear from some of these guys pushing 800hp through their standard ARP studs and OEM gaskets and see if they have ever pressure tested their coolant system and along with testing it over a long period of time... like 20 min of super hard WOT runs to get the psi built up. I would love to see a video of 800hp and a coolant sytem not leaking on a psi gauge. Not saying it is not possible but I would love to see it. [/QUOTE]