A1 heaadstuds vs ARP 425 vs ARP 625

skidootom

skidootom

Engineer
A1 heaadstuds vs ARP 425 vs ARP 625 ... anyone have any input/experience with these and what they are capable of on a 2010+ 6.7L? :tree:
 
I run the H-11's and no problems at all. To me, they are just as good as the 625's, just don't hurt your wallet as bad.
 
I'd like to get to the bottom of this discussion once and for all. Let's get some technical specs for the rods on the forum. Tensile strengths, how they were rolled, thread bearing capacities, Rockwell hardness tests, etc. and compare them side to side.
 
I'm a fan of A1 h-11's. But I don't have first hand knowledge of 1000+HP or 80+psi either
 
ControlFreak said:
I'd like to get to the bottom of this discussion once and for all. Let's get some technical specs for the rods on the forum. Tensile strengths, how they were rolled, thread bearing capacities, Rockwell hardness tests, etc. and compare them side to side.
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This would be good. Would be nice to know actual facts rather than playing it safe and buying the best. My thoughts were that if I was going to go to all that work I might as well put in the best I could.
 
I've been doing a lot of reading and between four different forums, both arp's and a1's websites, and talking to mechanics from some area performance shops. When I have some time in the morning I will post my findings.

Sent from my DROID RAZR using Tapatalk 2
 
First, a link to A1's website where they show some strength's a various alloys and metals: A1 Technologies

H11 alloys to have a high tensile strength but are considered poor for corrosion resistance. Understandably, this may be a non-issue because the studs are in oil. This was about the only info I could pull from the A1 website.

The ARP custom age 625 material seems to be a very high quality material and the method that ARP uses to manufacture their studs seem to be top notch. Their website details the manufacturing processes and material metallurgy used for production. A link to their website: ARP-bolts.com | ARP - World-leading Fastener Technology

The 625 material is one of their stronger materials from what I gathered with all the bells and whistles that go with it.

The 425's are made of the ARP 2000 material which does seem to be a quality grade material, however it does not have as high of a tensile strength as the 625 material.

A description from Glacier Diesel Power's website gives a good description of the 425 head studs:

"98.5-'10 Dodge 5.9L & 6.7L 24V 12mm ARP 2000 Head Stud Kit

To overcome head gasket failures that can occur in turbo-boosted Cummins diesel engines employed in truck and RV applications, industry leader ARP has introduced extra heavy-duty head studs for the popular 5.9L & 6.7L power plants. These ARP studs are rated at 220,000 psi tensile strength, and provide the clamping force required to keep cylinder heads from lifting due to higher combustion pressures.

The studs are manufactured in ARP's Santa Paula, CA plant from proprietary ARP 2000 material; with threads rolled after heat-treat to provide optimum fatigue strength. They are center less ground to assure perfect concentricity. The ends of the studs are broached to facilitate easy installation. This feature also enables the cylinder head to be removed in tight quarters. Also included in each kit are heat-treated, chrome-moly steel 12-point nuts and parallel-ground washers. They are black oxide finished for extra durability."

So in the end, my conclusion is that all three of these head studs would work well. I don't feel the 625's are overpriced, they have their application in extreme hp rigs. So it depends on where you're going to end up in the hp range.
 
ControlFreak said:
So in the end, my conclusion is that all three of these head studs would work well. I don't feel the 625's are overpriced, they have their application in extreme hp rigs. So it depends on where you're going to end up in the hp range.
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I agree 100, for a guy like me who changes his mind on a weekly basis 625's are a safe investment
 
625's are a must on a 6.7 at any point over stock. The cheaper ones are fine on 5.9s up to 1000hp. Any time we go over that, we always use the 625's. We are running 625s on the race truck with a stock 6.7 hg and 140+ psi boost. Havent blown a gasket yet.
 
Blacksdieselhp said:
625's are a must on a 6.7 at any point over stock. The cheaper ones are fine on 5.9s up to 1000hp. Any time we go over that, we always use the 625's. We are running 625s on the race truck with a stock 6.7 hg and 140+ psi boost. Havent blown a gasket yet.
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I'm a little confused. If 425s are fine on 5.9s up to 1000 hp, then why aren't they fine for a guy like me with a 6.7 that has the number 750hp in his head? Why do I need to jump to 625s?
 
So the 625's are a must on the 6.7's? I was hoping to get away with the 425's. I'm not going crazy or anything. Maybe 5-600 hp. That kinda blows!
 
After I get my clutch of course. I need to cut down on all my hobbies and misc bs and focus on my truck.
 
I think it is a case by case situation. A shop that is installing them, and has to back up their work, as well as charge shop time. I am guessing the labor on a stud install on a 6.7 would be in the $300 range. If putting the 625's in ensures that you won't have stud issues then I can totally relate to the 625's being an option.

I do feel that the 425's will offer extra clamping loads and hopefully that will suffice for a low HP application.
 
I have used every single brand and version on 6.7's. However the only two 6.7's I've used 425's on are not heavily modified and generally are stock except for deletes and aren't abused. The h11 and 625 trucks all have built Trans, upgraded turbos, and of larger injector and are ran fairly hard. So far no problems. This is a span of 1.5 years and 12 6.7's.
 
I've seen multiple failures of A1 and ARP 2000's but have yet to see a failure with ARP 625s, for me its the piece of mind knowing how well they've worked previously. I don't care how awesome the statics are, if they fail in real world high HP applications, I steer clear. And of course every build is different so I have builds we still use ARP 2000's on, just not extreme builds.

Lavon
 
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