Building a 4.7L low compression, supercharged S65 stroker motor - Page 4

Revo · 29th May 2012, 08:35

No one would sell you a few rods of it?

PencilGeek · 15th June 2012, 06:18

Quote:

Originally Posted by Revo

No one would sell you a few rods of it?

625 material fell through. We ended up going another route with 8740. Studs are now in progress. We have enough material for at least two sets of head studs...maybe three. Final specs will be about 220k PSI. 625 material would have been 260k PSI.

If you need a set, PM me.

Revo · 17th June 2012, 06:46

Is that the yield strength?

PencilGeek · 17th June 2012, 16:20

Quote:

Originally Posted by Revo

Is that the yield strength?

ARP calls is "bolt strenth index" -- but I've also seen them call it "bolt tensile strength."

redefined · 21st June 2012, 02:55

wow awesome build!

Revo · 21st June 2012, 07:22

Those are impressively high numbers then. Well beyond that of Titanium - about 30% higher, in fact. Is this hardened steel?

PencilGeek · 22nd June 2012, 16:38

Quote:

Originally Posted by Revo

Those are impressively high numbers then. Well beyond that of Titanium - about 30% higher, in fact. Is this hardened steel?

Here's what ARP says about 8740, 625, and Titanium:

8740 CHROME MOLY: Until the development of today’s modern alloys, chrome moly was popularly considered a high strength material. Now viewed as only moderate strength, 8740 chrome moly is seen as a good tough steel, with adequate fatigue properties for most racing applications, but only if the threads are rolled after heat-treatment, as is the standard ARP production practice. Typically, chrome moly is classified as a quench and temper steel, that can be heat-treated to deliver tensile strengths between 180,000 and 210,000 psi.

CUSTOM AGE 625 PLUS®: This newly formulated super-alloy demonstrates superior fatigue cycle life, tensile strength and toughness – with complete resistance to atmospheric corrosion and oxidation. ARP is the first to develop manufacturing and testing processes for fasteners with Custom Age 625+. Best of all it is less expensive and expected to soon replace MP-35 as the material of choice in the high strength, super-alloy field. Typical tensile strength is 260,000-280,000 psi.

TITANIUM: ARP now offers special order fasteners made of an alloy (Ti6Al-4V) that is specially heat-treated (a process developed by ARP's own Russ Sherman) and provides superior strength to other titanium alloys employed in racing and aerospace. The material has a nominal tensile strength of 180,000 psi, and is very corrosion resistant. The main advantage of titanium, of course, is its weight – which is about 40% lighter than a comparable fastener made of steel. Head studs and accessory bolts are ideal applications for this lightweight material.

M V10 · 5th August 2012, 20:48

Anything new?

PencilGeek · 10th August 2012, 05:36

Quote:

Originally Posted by M V10

Anything new?

Head studs are at the grinder right now getting threads put on.

PencilGeek · 30th August 2012, 21:57

Head studs are done and stretch test was completed. Without stretch test, no way to know proper torque specs. Ready to assemble top end of motor.

Somebody told me yesterday that I was being asked on another forum why I didn't just buy head studs from his favorite company. Since I know he reads this thread, here's my simple answer:

They never sent me the specs they promised, and they couldn't tell me what material was used.
The initial quote was overpriced -- approximately 2x what ARP charges for 8740, and 1.2x what ARP charges for 625...and I still didn't know what material they used.
I didn't feel comfortable using this company because I'm not convinced they have enough technical expertise to design the studs themselves.
Based on above point, I don't know if they would have even known to run a stretch test before trying to use the studs.