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Message: [QUOTE="Mdub707, post: 907153, member: 107"] I assumed you knew that they all stretch to some degree, but in such a technical thread I thought it was worth mentioning. Out of all of these "reports" of people stretching the studs, one would assume they're yielding? Or are these studs stretching just enough to allow leakage but still seal up when shut down? I mean, if they're yielding we should be able to physically measure the length of the stud to see if it has changed, no? It's all good, we're all on the same page here, just talking about it often brings up new ideas. I'm not familiar with the 625 ARP's, so I wasn't referring to them originally. If you read what I said carefully, I'm not saying higher tensile strength equals lower torque value, I'm saying for this specific case they work out this way to likely achieve the same clamping force. It makes sense. The threads per inch on each stud is exactly the same (you can thread an ARP nut onto an H11 stud), the tensile strength of the H11 is higher, the required torque value (as supplied by the mfg) is lower... one would assume they're likely close to the same clamping force. We can figure this out with math pretty easily and I may do that after I reply to this post completely. You're contradicting yourself here... LOL Your first statement implies the torque value changes tensile strength, but we both know that's not correct, it's simply a material property. You are regurgitating exactly what I said, the H11 stretches less (less torque required to seal) and exerts the same clamping force through the higher tensile strength. We're on the same page here... Just as an FYI, I have my mechanical engineering degree and I work for a company that supplies studs/nuts to the compressor world (think large GE compressors) and we also design and manufacture our own tensioning hardware. We stretch studs in a different manor than simply applying a torque wrench, we use hydraulics. We calculate the stretch needed of a stud to apply a specific clamping force and then we put our hydraulic nuts on the studs and stretch ALL of them at once. It eliminates the need to torque in a pattern of any sort and it eliminates torque scatter completely. We stretch, hand tighten the nuts down, then let the hydraulics off and bam... done deal. I completely agree with that. I wasn't even aware of the specs of the ARP 625's before this thread honestly. Not a lot of people are using them. What amazes me is the higher tensile strength AND the higher torque values. I'm surprised the block can take the abuse actually. Just glancing at the values, one would assume the 625's exert a higher clamping force because of it. Again, getting back to the relationship that tensile strength doesn't always equate to a given torque value, that is only the case if a desired clamping force is consistent. I'll run the numbers through our bolt loading calculator and see what clamping forces I get for comparison sake. Should be interesting. Correct, I don't disagree with this at all. I feel like this is exactly what I was trying to iterate in my original post LOL The increased stretch is needed to obtain the same clamping force because the tensile strength is slightly less. Makes perfect sense. I agree the ARP's will stretch easier. Honestly before your post this topic doesn't really get brought up much. There's just so many factors that go into the task of studding a 6.0 (head flatness, cracks, gaskets used, block surface, is the torque wrench calibrated...yada yada yada) and beyond that there is so many factors of how the truck is treated AFTER the job too... it's easy to point fingers at so many other things besides ARP's. Ok, this is kind of a slippery slope and confusing statement.... You say you must stretch the stud further to apply more torque to get 20,000psi less... are we talking tensile strength or clamping force here... We already agreed the tensile strength is just a given property of the material, and should have nothing to do with torque. The only relationship they have is when you have a given clamping force needed, then you can establish a relationship between torque needed based on tensile strength of the material. I know you understand it but the above statement almost goes against what we said earlier. Unless you're talking about clamping force, but I'm almost certain you're not. So based on the higher tensile strength, one could assume the H11's will hold up better under more extreme conditions. It really makes one scratch their head when you have guys pushing 1000 rwhp that claim to have no issues with standard ARP's though... which is why we question the stud job methods and the use of the truck. I think this is a good topic for discussion though. I think overall it's hard to just put it down to numbers like we're doing (the number part is easy), it's really going to come down to how the truck is used and what kind of power it's making. Some full out pulling trucks may need to tear down every few runs and check the torque on the studs. It's possible they loosen up as well. On my sub 500rwhp truck with ARP's, likely not necessary, but those guys pushing 60+psi and crazy cylinder pressures and tons of heat from huge injectors dumping all the fuel they can in 300'.... they may need to re-torque more often. [/QUOTE]