Best Studs/Head Gaskets?

[Ross@Flyindiesel]

Mines studded with the standard arps and oem gaskets. If it pukes with the s366 and 190/75s it's getting sold.

Hahahaha I like your mentality!! that just made my morning

 

[Mdub707]

He is one of the guys I have been talking to. It seems like standard arps start to stretch at around 40-50psi... If your prep work was perfect, surfaces flat, then a little bit of stretching is ok. But any imperfections and even the smallest amount of stretching will leak. Now once you get above 50-60psi then IMO standard ARPs will not hold up at all.



Interesting note... you can torque standard ARPs to about 215-250 without any problems. The reason you torque them down that much is they stretch slighly and reach their maximum tensile strength after being stretch to that point.


H-11 and Extreme studs recommend a much lower toruqe rating of around 185... supposedly if you torque them to 215-250 like the arps then you risk a chance of pulling the threads out of the block. I have never heard of that actually happening but the point I am making is that the h-11 and extreme studs options are not supposed to stretch

The H11's use a lower torque rating because the material they are made of has a higher tensile strength. So a lower torque value is used to obtain the same clamping force.

The point isn't NOT to stretch... they ALL stretch. We want them to stretch a little, we don't want them to yield. Stretch is what gives the clamping force. H11's stretch, ARP's stretch, every single fastener on the truck is stretched, otherwise the clamping force is 0. Once you yield the material (snap a stud, or stretch beyond deformation) your clamping force becomes.... 0.

We've had the discussion about torque values used on ARP's in the past. A lot of guys are going above what ARP specs of 215 ft/lbs using the ultra torque. No one can really give an answer as to why. It seems more go with the method of "bigger is better" without doing the math.

A1 technologies (who produces the H11's) went out of business a few weeks ago, so H11's are going to dry up in a hurry.

The only advantage I could see using the H11's over the ARP's is the lower torque value needed, and it would help those doing in-cab head gaskets. Has to be a lot easier torquing to 165 ft/lbs with the cab on.


I have to ponder what people are doing with their trucks that some blow gaskets and others have no issues. How are these trucks maintained, how are they used, what other mods do they have, who's tuning are they running... I think there's too many questions to answer for most of us to get and definitive answers as to why some blow and others don't. I have a buddy (who may be on here, Karls03) who has an 03 6.0, been tuned for well over 50k miles, runs it in the 1/4 miles (ran like a 13.9 on Gearhead tunes) and sled pulls with it, all on stock bolts and been that way since the beginning. He swears by letting his truck warm up 100% before even getting on it at all. He will drive, but wont give it much for throttle until his temps are at 180* +. He's had no issues....

 

[windrunner408]

...He swears by letting his truck warm up 100% before even getting on it at all. He will drive, but wont give it much for throttle until his temps are at 180* +. He's had no issues....

It's AMAZING how much more abuse stuff can take if the motor is at full operating temperature.

While I drive like a grandma most of the time anyways, I pretty much always let my truck idle for about 30-60 secs and then start driving easy (to help the heat up process and not just waste fuel idling). I just never go above about 20% throttle until it is warm and so far it's been solid (as far as the rotating assembly and what not goes) for 45k miles of either tuned and/or tuned and upgraded with injectors and turbos. I've done HGs twice for other reasons but it wasn't because they failed. The truck has had a lot of sh!t done to it trying various stuff and it is still running great.

Current HG setup is RCD's Black Platinums with regular ARPs torqued to 225ft-lbs.

 

[KCTurbos]

I digress and never should have stated that h11 don't EVER stretch... I just meant that they don't seem to stretch under our 6.0 powerstroke cylinder pressures while under high boost conditions people have reported that the arps do stretch. I can tell you from personal experience along with Jesse Warren that I have had trucks that only leak under really high boost and high cylinder pressures. That would mean that the studs are stretching. If the block or head was warped or the gaskets failed then it would leak even under low boost and low cylinder pressures.


Also my post are not to try and prove anyone wrong or start any arguments. I am researching this exact issue and have been for a while trying to develop a better/easier/cheaper solution for the 6.0 guys that wanna push bigger power without having to wonder about their gaskets. Bouncing my thoughts off of people help out with creativity and research power.

The H11's use a lower torque rating because the material they are made of has a higher tensile strength. So a lower torque value is used to obtain the same clamping force.

^^^^
I am sorry my friend but this information is not correct. Higher tensile strength does not equal lower torque value. I can see why you would think this but let me help you out a little.



h11 = 240,000 psi tensile strength torque to 185
arp = 220,000 psi tensile strenght torque to 215
625 arp = 250,000 tensile strength torque to 285


First off you can see that you must torque the standard ARPs down more than the h11 to achieve a lesser psi tensile strength.

Yep that is right. You have a higher tensile strength with with less toqure which would appear to make your statement correct... but... the arp 625s are torqued down even more than either stud to achieve even more tensile strength.


So what does that mean??? How can one be torqued more and the other be torqued less and acheive different tensile strengths. Well it is because the h11 steel stretches less to get the same clamping force. This means that they stretch less than the ARPs do. That is why you can torque them down less and get a higher tensile strength. The truth of the matter is the tensile strength does not change with how hard you torque down the bolts. "Tensile strength is indicated by the maxima of a stress-strain curve and, in general, indicates when necking will occur". Tensile strength is predetermined before you even put the stud in the truck. The tensile strength simply refers to how much force the metal can take before it yields and bottlenecks.

There is so much more to the different types of materials being used than just the tensile strength... but I can tell you that simply by looking at the tensile strength and torque rating that arps stretch more than h11 or h13 tool steel

The only advantage I could see using the H11's over the ARP's is the lower torque value needed, and it would help those doing in-cab head gaskets. Has to be a lot easier torquing to 165 ft/lbs with the cab on.

Actually the main advantage is the higher tensile strength. But it also has to do with stretching.




Think of it like this. Once you get the nuts nice and tight on the stud without applying any torque then the studs are all the same length and everything is flat and tight. Now once you start torquing down the nut you can actually see the threads starting to poke out above the nut... that is the stud stretching, not the head squishing... it will stretch the stud. Remember the torque reading you are getting not just the resistance of the stud stretching, it is also the friction. That is why ARP uses special lube. That is also why with the new ultra lube that they lowered the torque rating. The fact of the matter is you must stretch the arps farther than the h11s to get the same tensile strength/clamping force. That means for our application that the arps will stretch easier under the same load (actually stretch easier under less load).



So if we are just talking about standard ARP vs H11 then you must stretch the stud farther and apply more torque to get 20,000psi less. This info seems to support the theory about why standard arps dont seem to hold up under high hp and high psi. This would also explain why some guys had nothing but problems with their standard arps and switched to h11s and all their issues went away (without doing anything different and no machine work)






Some more food for thought... from what I have researched the standard TTY bolts had a tensile strength of 180,000 vs the 220,000 from the standard ARPs. Some people claim that the standard TTY bolts stretched and that is why a higher tensile strength was used. That is why the higher 220,000 tensile strength of ARPs helps not to blow gaskets. But in theory that extra tensile strength will only go so far before the studs start stretching again. How far exactly is anyone's guess but to say that the standard tty bolts will not hold up at all and then assume that the 40,000 extra psi tensile strength from the standard ARPs is an end all win all does not add up in my mind. That is why I think many guys above 550-650hp seem to have repeat failures with standard ARPs, especially with big vgt turbos that can build max boost at much lower rpms, pulling trucks that get abused, and anyone pushing 60+ psi through the motor.

 

[swinky]

This is a pretty open ended conversation. If it's not your truck you don't know what it's been through. Who's to say jesse hasn't abused his truck before it's warm? Or done some Crazy ass tune with insane amounts of timing.

Maybe arp had a bad batch. Lots of good info in here but to say only 5 out of 50 studded 6.0s last under high hp is just insane.

 

[KCTurbos]

This is a pretty open ended conversation. If it's not your truck you don't know what it's been through. Who's to say jesse hasn't abused his truck before it's warm? Or done some Crazy ass tune with insane amounts of timing.

Maybe arp had a bad batch. Lots of good info in here but to say only 5 out of 50 studded 6.0s last under high hp is just insane.

LOL... you might be right about the 5 out of 50... Maybe... but I wonder how many guys actually use their high hp trucks for towing and/or actually test for slightly blown gaskets. Slightly blown heads will not show up during your average spirited driving.

One of the trucks is my own personal truck along with lots of other people that I know. I know very few guys that actual run a 600+ hp truck and the majority of them have leaking gaskets or think they are leaking. I am not just going off of heresay that I heard about some other guys truck. Not saying that I am 100% correct or anything like that. Many of those guys are right here on the forums but most keep their possible leaking gaskets under wraps.

 

[swinky]

I don't think anyone is keeping it under wraps. You're doing way more research than me so I don't want you to think im arguing.

600hp has nothing to do with it imo It's heat and cylinder pressure.

 

[KCTurbos]

I don't think anyone is keeping it under wraps. You're doing way more research than me so I don't want you to think im arguing.

600hp has nothing to do with it imo It's heat and cylinder pressure.

I wont post names and I don't spend all my time on one forum... but i know plenty of guys that think their heads are leaking and don't go talking about it on the forums. But I also know lots more people who have had multiple repeat failures who have made it known.

Are you implying that 600hp, head, and cylinder pressures are mutually exclusive? I would say they are very closely related. More fuel + more air = more power... no way to get around having more power and more cylinder pressure... but you can try to keep them down.

 

[Mdub707]

I digress and never should have stated that h11 don't EVER stretch... I just meant that they don't seem to stretch under our 6.0 powerstroke cylinder pressures while under high boost conditions people have reported that the arps do stretch. I can tell you from personal experience along with Jesse Warren that I have had trucks that only leak under really high boost and high cylinder pressures. That would mean that the studs are stretching. If the block or head was warped or the gaskets failed then it would leak even under low boost and low cylinder pressures.

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?

Also my post are not to try and prove anyone wrong or start any arguments. I am researching this exact issue and have been for a while trying to develop a better/easier/cheaper solution for the 6.0 guys that wanna push bigger power without having to wonder about their gaskets. Bouncing my thoughts off of people help out with creativity and research power.

It's all good, we're all on the same page here, just talking about it often brings up new ideas.

I am sorry my friend but this information is not correct. Higher tensile strength does not equal lower torque value. I can see why you would think this but let me help you out a little.


h11 = 240,000 psi tensile strength torque to 185
arp = 220,000 psi tensile strenght torque to 215
625 arp = 250,000 tensile strength torque to 285

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

First off you can see that you must torque the standard ARPs down more than the h11 to achieve a lesser psi tensile strength.

The truth of the matter is the tensile strength does not change with how hard you torque down the bolts.

Your first statement implies the torque value changes tensile strength, but we both know that's not correct, it's simply a material property.

Yep that is right. You have a higher tensile strength with with less toqure which would appear to make your statement correct... but... the arp 625s are torqued down even more than either stud to achieve even more tensile strength.


So what does that mean??? How can one be torqued more and the other be torqued less and acheive different tensile strengths. Well it is because the h11 steel stretches less to get the same clamping force. This means that they stretch less than the ARPs do. That is why you can torque them down less and get a higher tensile strength. The truth of the matter is the tensile strength does not change with how hard you torque down the bolts. "Tensile strength is indicated by the maxima of a stress-strain curve and, in general, indicates when necking will occur". Tensile strength is predetermined before you even put the stud in the truck. The tensile strength simply refers to how much force the metal can take before it yields and bottlenecks.

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.

There is so much more to the different types of materials being used than just the tensile strength... but I can tell you that simply by looking at the tensile strength and torque rating that arps stretch more than h11 or h13 tool steel

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.

Think of it like this. Once you get the nuts nice and tight on the stud without applying any torque then the studs are all the same length and everything is flat and tight. Now once you start torquing down the nut you can actually see the threads starting to poke out above the nut... that is the stud stretching, not the head squishing... it will stretch the stud. Remember the torque reading you are getting not just the resistance of the stud stretching, it is also the friction. That is why ARP uses special lube. That is also why with the new ultra lube that they lowered the torque rating. The fact of the matter is you must stretch the arps farther than the h11s to get the same tensile strength/clamping force. That means for our application that the arps will stretch easier under the same load (actually stretch easier under less load).

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.

So if we are just talking about standard ARP vs H11 then you must stretch the stud farther and apply more torque to get 20,000psi less. This info seems to support the theory about why standard arps dont seem to hold up under high hp and high psi. This would also explain why some guys had nothing but problems with their standard arps and switched to h11s and all their issues went away (without doing anything different and no machine work)

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.

Some more food for thought... from what I have researched the standard TTY bolts had a tensile strength of 180,000 vs the 220,000 from the standard ARPs. Some people claim that the standard TTY bolts stretched and that is why a higher tensile strength was used. That is why the higher 220,000 tensile strength of ARPs helps not to blow gaskets. But in theory that extra tensile strength will only go so far before the studs start stretching again. How far exactly is anyone's guess but to say that the standard tty bolts will not hold up at all and then assume that the 40,000 extra psi tensile strength from the standard ARPs is an end all win all does not add up in my mind. That is why I think many guys above 550-650hp seem to have repeat failures with standard ARPs, especially with big vgt turbos that can build max boost at much lower rpms, pulling trucks that get abused, and anyone pushing 60+ psi through the motor.

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.

 

[Mdub707]

Here's the bolt loading calculator my company offers for free on their website:

http://riverhawk.com/boltloading.php


You should very easily be able to check anything you want with that.

 

[Mdub707]

Also, aren't the H11's only torqued to 175 ft/lbs? (recommended values)


And does anyone remember the TPI for the studs on a 6.0? I know the standard ARP's and H11's share the same thread pitch. Not sure on the 625's though...

Ivan and I figured this out once, and I can find the thread where we were discussing this, but we swapped the TPI numbers in PM's and I don't have the PM anymore. GahhH!

 

[KCTurbos]

I will try not to rebuttal every post you made (that gets very long)


Considering your background I know you know this info but I am just posting it for clarification. The main confusion we seem to have is that tensile strength and clamping force are not the same thing but closely related. Tensile strength refers the the property of the metal and how much stress it can handle before yielding. Clamping force is how hard you clamped down. If you were to just hand tighten the nut on the stud then you would have almost 0 clamping force but the stud could still hand 220,000 psi tensile strength. Theoretically once you have completely torqued the stud down you have reached the near maximum tensile strength of the stud and maximum clamping force(eliminating all other variables that cannot be controlled). That is why i said that with less tq on the h11 stud you are reaching 20,000psi more of tensile strength (without yielding the stud) which will equate to more clamping force with less stretching of the stud.


Now I agree with you that the arp 625 exibit weird properties you have to stretch/tq them down even more to reach the higher clamping force/psi tensile yield point.

 

[Mdub707]

I will try not to rebuttal every post you made (that gets very long)


Considering your background I know you know this info but I am just posting it for clarification. The main confusion we seem to have is that tensile strength and clamping force are not the same thing but closely related. Tensile strength refers the the property of the metal and how much stress it can handle before yielding. Clamping force is how hard you clamped down. If you were to just hand tighten the nut on the stud then you would have almost 0 clamping force but the stud could still hand 220,000 psi tensile strength. Theoretically once you have completely torqued the stud down you have reached the near maximum tensile strength of the stud and maximum clamping force(eliminating all other variables that cannot be controlled). That is why i said that with less tq on the h11 stud you are reaching 20,000psi more of tensile strength (without yielding the stud) which will equate to more clamping force with less stretching of the stud.


Now I agree with you that the arp 625 exibit weird properties you have to stretch/tq them down even more to reach the higher clamping force/psi tensile yield point.

Ok, that makes much more sense to me the way it is explained now. I take things too literally at times.

It would be interesting to compare the TPI of the 625's to the H11's and standard ARP's.

If the TPI is the same, the tensile strength is higher and the torque value is way higher, one would assume the clamping force is much higher.

At what point do we start to worry about block distortion, because I've heard/read of it being an issue even with the H11's getting torqued higher than the recommended 175 ft/lbs. What are your thoughts on that? I've read it can throw the cylinders out of round.

 

[KCTurbos]

At what point do we start to worry about block distortion, because I've heard/read of it being an issue even with the H11's getting torqued higher than the recommended 175 ft/lbs. What are your thoughts on that? I've read it can throw the cylinders out of round.

I don't know the answer to this. I have heard many rumors and theories of this happening but never seen any documented cases. IMO the stud would yield before you rip the threads out of the block... but it would be cool if someone did the experiment on some old bad block and heads just to test.

 

[KCTurbos]

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.

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.

 

[Mdub707]

Not many guys out there DD'ing an 800+hp 6.0, most are hooked to a sled or driving down the track, those guys aren't doing 20+ minutes of WOT runs either. I think it's safe to say this is territory where there simply isn't enough documentation to support one way or the other.

As for studs yielding, that's definitely true. Ellerton said they snapped an ARP torquing them to 300 ft/lbs, didn't pull out of the block, but I can't help but wonder what it does to the threads in the block. It's amazing to me. We run tremendous amounts of pull on some of our tensioners, we have actually designed and patented our own threads to help with this. I know the studs used for the 6.0 are roll formed to help, and apparently that's good enough if the stud snaps before it pulls out of the block.

There's a kid on the powerstroke FB page asking how to get broken studs out of the block right now. He has 3 studs snapped off IN the block that are below the block surface and can't get them out. Trying to get some info from him right now.

 

[KCTurbos]

I know what you mean about the 800hp truck... my point was how many guys pushing 600+ hp have checked to see if they have a slight leak. The guys I know that went and checked were very disappointed.

 

[bigrpowr]

just to clarify, the material is h-13 , which is superior to h-11 , with most of the same characteristics .

 

[KCTurbos]

just to clarify, the material is h-13 , which is superior to h-11 , with most of the same characteristics .

agreed... I just know most guys are more familiar with the h11 terminology... I did not want to have to type h11/h13 everytime

 

[KCTurbos]

Here is another thought/theory that I have been going over recently.


PSI tensile strength is the maximum amount of force the stud can take
Clamping force is exhibited by torquing the stud down.
The closer you get to reaching the maximum tensile strength the more clamping force


I know this must sound simple to some guys but it makes me wonder exactly where the stud reaches the maximum tensile strength and yields. 215, 240, 260 etc... you want to get as close as possible to the yielding point without passing it. ARP would never tell you the exact figure. They must guestimate a little low. There are so many different variables that could come into affect that needs to have a little fudge room. Probably the most important being the torque wrench being calibrated correctly and also being used correctly.


This is why some shops do not use a torque wrench for the last few turns. They just use a certain number of turns... which essentially is just stretching the stud to a certain point everytime. I could actually see this method being more acurate than a tq wrench in reaching the same clamping force everytime... but not sure how you achieve a baseline.