So you still haven't done a test with the inconel studs? This was with 316, correct?

 

No, this was with Inconel.

 

:(

Begi manifold?

 

What grade Inconel was that,if we can ask now..Savington?
-G-

 

I want to do one more test, with safety wire as a mechanical locker. That way the only failure mode is creep/stretch. If it doesn't work, I'll drop the grade and we can discuss whether a second test on a second alloy is worth doing.

 

for posterity and curiosity, what'd you torque them to?

 

I don't have a crow's foot, but I was sure to keep it light, under 10 ft.lbs for everything. Studs into the manifold, then nuts onto the studs. That's the right way to go for material expansion, and the WRONG way to go for keeping the fasteners in. If you use light torque, you've got to have something holding them in - safety wire, Stage 8s and roll pins in the studs, something.

 

When's d-day?

 

I'll agree with that. 10 ft lbs on a normal day could make them loose on a very cold day.

but wasn't the point of "unobtanium" studs that you could torque them normally and they'd still do well with the thermal expansion?

 

I don't see how 10ft.lbs will ever stay on without additional Resbond, sport weld or whatever. Any 10ft.lbs nut on track will be gone before I re-enter the pits, let alone the turbo to manifold nut. Also, 10ft.lbs won't even overcome material imperfection, like drops of ceramic coating, rust, debries.

Then how do you explain my **** is still tight? After I tightened the nuts as good as I could with a wrench, they were spot welded.

 

Sav: try flange nuts with Resbond on SS or Inconel. Rebond on studs, insert and let them dry. Then mount turbo and tighten nuts, let them dry too. 24hrs before you even start the engine. Tighten the nuts pretty good. Flange nuts take well over 10ft.lbs Basically, then you've got what I've got, minus spot welds.

 

Thats the idea to resbond it on, or spot weld it, whatever.

I can't explain anything, you've got the real world right there on your manifold. All I have is numbers. Testing tells the real deal, and for your application it worked. End of story.

If the studs are plastically deforming on sav's manifold and not simply just spinning off though, less preload will help.

 

I guess you don't DD the car? 4 Laps seems like the sort of thing that might show up on the street if you're even half the ******* I am. :-) I can't say how well my set up would work on the track, but I can say there's a definitely 50:1 improvement in whatever I have now from the 6-8 combinations I tried before it.

Can you tell if the nuts moved at all?

 

Are the studs longer after the test?If so what portion of the studs permanently deformed?There in lies the answer to the problem.
-G-

 

Good question. I purchased 8 prototype studs. I'll remove one or two from the car today and compare them to the other 4.

 

Try and get the measurements with some caliperss and compare the average of the unused studs to the Used studs and then measure the threads and the shank Im truly interested,I think what might be happening is the manifold is heating up faster than the stud allowing the threads to pull out of the casting.I couldnt immagine that even low alloy inconel would creep that much at the temps you are generating.
-G-

 

Yeah - it's a long shot you'll see 20 mils but maybe you will. Measuring overall length before you put them in would be pretty cool - if you can spare the time I'd suggest micing the next set before they go in.

Kudos for making the effort.

 

As soon as my car is done,I need to find some way of flogging the living hell out of it to see what my bolts will hold like.3/8"-24 shoulder bolts 316 ss.1/8" thick 316 washers mechanical locknuts,safty wired heads.Going to torque down to 45 ft.lbs.,manifold flange is 9/16" thick 1018 steel.Low mount design with heim joint brce to engine block from turbo.I need a camera to doc. this stuff as it gets built.
-=G=-

 

Next test is tenatively scheduled for this coming weekend. Resbond, Inconel, and Stage 8 lockers.

 

could you possibly do a 30 ft-lb new-ATP/audi nut just for me?

just one of four. with inconel stud.