[oldman]

The old LS studs were 7/16 or 11.11mm and are made from 200,000 PSI material. The torque is 80 ft -lbs. The LT1 stud is 12mm and 220,000 PSI material. The torque is 115 ft - lbs. I can do the PI R Squared to find the areas and then look at the yield strength, but off the top of my head I'm looking the LT1 stud has 13% more area and is made of a material with 10% more yield strength so should have about 23% more torque so 98 ft - lbs would be what I would expect.

For the builder and the arm chair internet engineers, why is ARP recommending a torque that is much closer to stud failure on the LT1, the engines share the same basic design and the LT1 stud is already 13% bigger. The clamping force (once again off the top of my head) must be 33% higher or something like a full ton per bolt more clamping.

Yes I'm fully aware that a stud has to stretch to provide clamping and not back off. Basically I'm saying 80 ft - lbs was pretty tight for a stud into an aluminum block and probably much more clamping force then the LS torque to yield bolts, 115 ft - lbs a stud to me is insanely tight for a street engine and could be near DOUBLE the clamping force of the stock torque to yield LT1 head bolt. I'm just not feeling double.

I may (since it is my engine) go with 110 or even 105 ft - lbs. With ARP ultra-torque lube.

I've read through the ARP ulta-torque white paper and their yield strength white paper on 200,000 vs 220,000 PSI studs.

So anybody want to chime in?

[oldman]

I did that above from the top of my head
The plain ARP stud for the LS is M11 or 95mm x mm of clamp area and 70 ft - lbs
The ARP 2000 stud 234-4345 is 80 ft -lbs

The LT1 stud is an M12 or 113mm x mm of clamp area (cross section of stud, yes I know not really as the actual barrel of the stud is smaller that thread) so really the LT1 stud has about 20% more are at the thread and dunno say 15% at the barrel. But it is the same material as the LS1 stud above. So I would say roughly 92 ft -lbs should be the toque of the LT1 stud, same material, about the same length and 15% more cross section, but it is NOT, it is 115 ft -lbs! OHG. I check on my HonDha and it is a M11 (thread) 200,000 PSI aluminum block and head, about the same length and it is 80 ft -lbs.

I busted out the caliper and the LT1 stud is .443 inches or 11.25 mm on the barrel. Found a general toque chart for ARP based on barrel:
http://ipgparts.com/blog/arp-head-st...stretch-specs/

For a 11mm stud with the 220,000 psi material = 92 ft -lbs sure this stud is slightly bigger at 11.25 so say 100 ft -lbs. Once again my gut feeling is correct. BTW 7/16 barrel = 11.11 mm, yes I read the "always follow directions on kit...