get your minds out of the gutter!!!!!!

Don---what boost levels have you seen with these new studs and how many runs have they seen---any info on that---chris

 

no data. Probably less than 60 PSI.

I sold all the first batch we got. Only 3 folks have them installed so far.

Boost level is not as important as: the temp of that boost and if you have drugs or not.

If your studs are holding now....you are probabaly OK!!



Don~

 

I have NOS and push 80 with or without the NOS--that's been for the last 3yrs and for the last 1.5 yrs I'm double oringed with receiver grooves and studs---so 80 vs 60 is a big increase and I may see more as I've done some tuning and have some bigger sticks to slap in--so I'm trying to keep the head on and if I see the need to get some other studs vs doing the 14mm studs I'd rather do the stock size bolts with the strongest clamping force vs the 14mm route---thus all my questions---chris

 

Chris, I just pushed mine to 65lbs with the drag comp on 5-5. Sustained run from 65 to 115 mph. My new mach 6s never really cleared up even at 65lbs of boost and egts were over 1600. I am going out in a little while and inspect the head real good, but the initial inspection looks good. Tim

 

thanks--chris

 

Your 12mm 4340 steel studs you have now are close to the 180,000 psi range in yield. Provided they are not overtorqued.

The ARP's are running about 220,000- 225,000 psi torqued to a paltry 96 Ft lbs using moly. This is 75% of yield. Slightly more TQ can be applied, but its just not needed in 99% of cases.

Clamp force and yield is higher with the ARP's.

This will help to put more clamp and localized pressure where you want it...without cylinder wall distortion.

Contrary to popular belief...the studs dont "stretch" during engine operation as quoted time and time again by others.

The gasket material gets hot from combustion and begins to weaken some... coupled with the force of the gas pressure the gasket is pushed out of the joint. The head does not "lift up" and the bolts dont spring up. So...you fight the trouble with more localized pressure via o-rings or similar in the combustion seal area and install fasteners that can clamp the area with as much pressure as you can get.

The worse flange is a bolt threaded into a receiver. The second best is a stud, and the very best is a through bolt and a nut on the opposing side. The best we can get is a stud in the block.

In your case with higher pressure VIA Nitrous and the heat generated when you compress air to 80 PSI...you are a candidate for a stud made from higher yield material. 260,000 - 280,000 PSI.

This is not a cheap date either. The higher force superalloys are spendy, suffer from corrosion more often, and just dont play well with everyday use. Top fuel and such do well, but daily drivers dont.

Its close to a grand to have the superalloy stuff made at ARP.

Are the 220,000 ARP's better than the 4340? Yes. Are they enough for 80 PSI and Nitrous? Perhaps, but IMO in a situation like that...always over engineer the fix. Get the best material stud you can live with...all things considered.

Don~

 

how does one get better clamping force from different matl's--is it thread distortion that makes the difference???

what can the block handle for torque/ clamping force---when does one surpass it's ability to hold---I mean can it handle the 260k-280k psi that the stud can???

I'm not sure this has ever been discussed--chris

 

That is where the 14mm studs become attractive. The majority of the guys rebuilding their motors from the ground up and going for big power, so installing the larger studs at that time is by far the most logical choice. You get a lot more thread area in the block, so you have less risk of a tearout. With the same strength material (220ksi+), a 14mm stud is going to have a MUCH higher clamp load than a 12mm stud. My chart (from ARP ) shows 19,500 lbs for a 12mm stud at 96 lbs torque, and right at 26,000 pounds for the 14mm's. Bolt tension is goverened by the formula T=KDP (that's not killer dowel pin)... where applied torque (T) equals a torque-friction coefficient (K) times nominal bolt diamter (D) times bolt clamp load (P). You generally tighten to 75% of bolt proofload, and clamp load is this 75% times the tensile stress area. In other words... the bigger the bolt, the higher the clamp load, and the more torque to get it tight (exponentially in fact). Corrosion issues are a factor with any high strength steel, but there are methods to combat it. Coatings, and post coat bakings to eliminate hydrogen embrittlement are common. You can read all about it under SAE AMS-2759 (that's a current spec btw ).

These 12s are good... better than what's out there, but for the guys who want to run big boost w/ drugs... you need a bigger stud to cure your worries.

John

 

Banshee,

Everything in your post is correct on clamp load, etc.

The current 14mm's are not coated with anything. They have a bead blast finish. They rust with ease. Hydrogen embrittlement does not show up until you TQ the fastener. Most manufacturers dont or cant deal with this problem during manufacturing.

With the ARP's you can sell them to anyone. The low TQ rating puts them in a range where block distortion does not happen. With 14's you are in trouble right from the start from the higher TQ you apply to the flange.

Imagine the block when you apply too much force to the top section. It actually looks scaloped in the top region of the cylinder bore and that region is compacted or squished down. Ring seal becomes a problem. Not only do you have to remove material from the block but from the head as well. They begin to loose rigidity. This is not an option for me, but may be for guys who are ultra serious and can deal with the distortion using other boring and honing methods.

The 12's are a drop in application, provide enough force to deal with a large percentage people, and they are very resistant to corrosion. The ARP 2000 was originally designed for steam plant flanges where corrosion was a problem.

Yes, the 14's will provide additional clamp force. But , if you are not going to do a total rebuild and use the proper methods of rebuild, torque plate honing, and be certain the studs will not cause too much distortion in the head and block...your stealing from Paul to pay Peter.

Last year when I contacted BHJ to build a TQ plate for me to use during my rebuild I was surprised to hear they had only built one for the aftermarket. The rest had been built for the guys at Mopar recon. As of 3 months ago BHJ had built one for a vendor in the West. Its sad that so many folks bought 14mm's and were never told their cylinders needed to be rebored and honed.

Don~

 

You're right that the 14s do not come coated, but they can be coated. Application of black oxide, for example, will provide corrosion protection without comprimising the strength of the bolt. The shop doing the work on dad's motor are doing just that. As for the distortion goes, that can be handled by machining with deck plates (as you mentioned) to get rid of the minor distortion you will get. Any high performance shop worth their salt should know this and machine the block this way. Since going to the 14s requires a teardown anyway why not take care of the other machine work at the same time? I'm sure other companies besides BHJ are capable of making deck plates and machining fixtures.

As far as your 12s go, are you saying there will be no appreciable distortion with the stud vs. a stock bolt?

 

No appreciable distortion is correct. Yep , black oxide is a fix for corrosion, but it also wears off with use. Retorques, etc. Its a crutch IMO. Using a resistant material is a better mousetrap from the get go.

If I was going to do a rebuild for max HP and effort I would:

Use a 12mm stud from Custom Age 625 at 280,000 PSI. TQ plate hone the block and forgo the 14's. Unless we had a block that was dimensionally more stable or cast to accept a 14. Then I would go to a 14 in ARP2000 or CA 625. Until then the homework was not done to use 14's. IMO only of course.

Don~

 

Hey Banshee,

Just curious, but why are the 12mm 4340 studs instucted to be Tq'd to 135 ft lbs? Did I miss something? Is this not right on the line of breakage? I know the yield is no higher up there...so do you have any insight?

Don~

 

Don,

The I'm pretty sure the 14s are 135 and their 12s are 90. I could be wrong though. Also, remember your 96? ft-lbs of torque is with the ARP moly lube. Is that torque listed with a completely clean & dry fastener? If that's the case then 135 would probably be pretty close to the correct elongation. If it was 135 with lube you wouldn't break the stud, but it would plastically deform it since that torque puts it right at the end of the yield strength. The lube, oil, or dry fastener is what changes (lowers) the K in T=KDP, so the more slippery the thread the less torque is required to get the same stretch & clamp.

 

Don:

FWIW, the 12mm studs that were installed in my 96' 12 valve
were torqued to 120 ft.lbs., not 135. Those studs were coated
with the black oxide you guys described. They went 120,000
miles with no problems at all, including all the time I "punished"
them with continual 60+lbs. of boost with the B-1 Turbos I
tried for almost a year. Upon their removal, they looked
to be in excellent shape, no discoloration or corrosion on
ANY of them and they were alot easier to remove than I
thought they would be!

---------
John_P

 

Even stock bolts would have been fine for a single charger truck. They work good in twin turbo apps when everything is installed correctly too.

Im aware the 4340 studs are coated. We were addressing the H-11 tool steel fasteners that are bead blasted and not coated. Prone to rust and hydrogen embrittlement.

4340 studs are advertised at 180,000 psi. Most are less than 160,000. This is as good as stock bolts with all things considered. Mostly a waste of cash. Enterprise has used the stock bolts for years and a single o-ring. Myself as well. Sleddy even used the stock fasteners in his twin turbo puller.

I wonder who it was that was selling the Chinese stuff? I have some here I ordered from a vendor a few years back. I just use them on my o-ring tool to fasten it to the head or block. They are not worth much more.

Don~