Blowing stacked head gaskets.

[mbarryracing]

I believe even at 42#, the threads in the thin aluminum block casting have already starting to fail. This is well below the torque needed to yield the bigger studs properly, the block is failing faster.
A tell tale sign is the block finally breaking at 45# (only 3 lbs more)... by design it should fail well over the # failure point of the stud or it's too weak.
So when your torquing your "big stud", r u stretching / failing the block threads or adaquately yielding the stud? An under yielded thicker stud (loose rubber band) has less clamp force on the head than a properly yielded stock stud (taunt rubber band)... Looks impressive, though! Must be fast...

 

[HURRICANE]

It's good to have this discussion as it brings everyones opinion together.I can't say that I agree with the talk so far.When we are working on a boosted engine,we throw the stock studs far,far away.They are not even close the adiquate to clamp the head,no mater how you torque them.The cylinder pressure will stretch them over 16lbs boost or so.I will always use the 10mm chrome molly stud and increase the torque.Sometimes we will torque the studs to 50lbfs but I believe that 45lbfs is safe.It is the ability to increase the cylinder pressure that cracks the blocks.I have never cracked a block under 400hp and we have tried high torque using 12mm studs.We've been to 90flbs.
Anything over 15lbs boost,go to hard studs.Over 22lbs boost,you will need the hurricane block.We have found these boost #'s to be a rule of thumb providing that there is no detonation

 

[mbarryracing]

Good input, I wonder if the studs I saw break block bosses during installation were larger then? The breaking I was refering to was during tightening, not during running and I do not know for sure the size but I think they might have been bigger than 10mm... And who is to say that we are talking apples to apples with aftermarket stud materials, too?
Can't say I have seen a broken block from combustion pressures yet, but you guys are definitely at a higher level so that can surely alter opinion on this as well.
I've witnessed well over 20lbs boost with stock studs on several machines without incident, but there are so many other variables that dictate results that it can't really be compared and I can't argue with proven experience at that level...

 

[Blue shadow]

will said my friend

 

[Skydog]

Right on guys!!!! GODD STUFF!!!

 

[mulot30th]

I believe even at 42#, the threads in the thin aluminum block casting have already starting to fail. This is well below the torque needed to yield the bigger studs properly, the block is failing faster.
A tell tale sign is the block finally breaking at 45# (only 3 lbs more)... by design it should fail well over the # failure point of the stud or it's too weak.
So when your torquing your "big stud", r u stretching / failing the block threads or adaquately yielding the stud? An under yielded thicker stud (loose rubber band) has less clamp force on the head than a properly yielded stock stud (taunt rubber band)... Looks impressive, though! Must be fast...

I have NEVER had any problem at 42# torque. Done this many many times on different engines.

Only thing, on rx1 engines... center rear stud... the block may... crack... (I have seen this happen one time.

 

[lakercr]

Couple quick points on torquing these heads (or anything else) for those who might not necessarily know...

Threads must be clean (like, hospital clean). All mating surfaces washers (both sides), threads, nuts need to be lubricated. Moly is best (subtract about 10% from your torque value if using moly) but oil is OK as well. You want the cam of the torque wrench as close to the nut or bolt you're torquing as possible (avoid using an extension wherever possibe) and ensure that the wrench is 90 degrees to whatever you're torquing. The better quality the wrench is, the less of an issues the last one is, but there is still some play even in a $300 Snap-on wrench, and this does make a difference. Stock blocks will take 45 lbs/ft no problem if it is an accurate value. Get any of the above wrong though and your torque # is pretty much meaningless.

 

[Ted Jannetty]

Any thing over 18 psi should have the ARP studs .

That's debatable.

 

[mbarryracing]

hahaha, you gotta love this forum! We do all have something spectacular in common...

 

[Yamanator]

Ok guys, not to steal the thread here but how do feel about sleeving 2 cylinders and then running boost on that motor? I have a block at the machine shop right now getting 2 sleeves put in it and then getting redecked and was just wondering when I get it back is it ok to run 2 head gaskets and 10 pounds of boost on a stage 1 supercharger? I just want to know if the sleeved block will hold up! it should be brand new right? I will have 2 brand new pistons in it and running lower compression, should be fine right? Let me know what your thoughts are because I do have people interested in my supercharger kit, and if you think the motor won't hold up with this setup, I will probably sell it. Thanks for any input, THIS FREAKIN SIGHT ROCKS........................

OH YEAH, THIS IS ON A 04 WARRIOR WITH 2600 MILES ON THE MOTOR.