I get using inconel for the manifold to turbo studs, how 'bout for the 5-bolt turbo to downpipe flange? Should those be inconel...SS...other?

I think it depends on how fast you are

if you are bundy, you need inco

most other peasants are fine with regular

I run stage 8 locking bolts. Normal nuts backed off quickly.

I was talking about the turbo/dp studs that he asked about, not the mani/turbo.

I agree that if you track, the mani/turbo studs should be inco, no exceptions.

Daily driving/ hard street driving/ even autocross standard studs and common methods will likely work fine for the turbo to manifold joint.

Run laps on a track as fast or any faster than the spec miata guys do with half or less the HP and no turbo Then with standard steel, high grade steel, or SS studs of any grade your turbo will fall off within a few days of use no mater what washers, nuts, or locking methods you choose to employ has been my experiance.

I think the text you're quoting was in reference to turbo-to-DP studs. AFAIK you're the only only with those loosening. :)

So:

- street/autox driving: no inco needed.
- hard track driving: inco needed for manifold-to-turbo.
- bbundy driving: inco needed to turbo-to-DP.

--Ian

I’m not using Inco on the turbo-to-DP they last for quite a while with a few qualifications.

1) Failure of or coming loose of my downpipe to transmission bell housing support bracket will create a very short life for the turbo to downpipe studs. As long as that stays put I’m good.

2) failure of or coming loose of the downpipe to transmission bell housing support bracket also results in short time between cracks developing in my mild steel long runner turbo manifold in and around the collector.

3) failure of or coming loose of my turbine housing downpipe flange to engine block support bracket (some may call it a crane) results in an even shorter time before the mild steel long runner turbo manifold starts to crack in and around the collector.

I've iterated through the support brackets design and have them fairly robust now. they stay tight and dont crack very often. I have not seen any of the pre-fabbed kits with the necessary support brackets up to snuff in my opinion and turbo to downpipe studs will have a shorter life as a result. With a short runner/ cast manifold you probably can get away without the crane and the manifold will also last longer than what Im using. I’ve gotten it robust enough now it will just about last a full season without too much fuss. After about 5 years the manifold will have several crack repairs and probably time to start over with a new manifold.

Do you have pictures of the downpipe to transmissions support bracket?

Damn straight.

Both FM and TSE sell legitimate 8mm inconel studs. I know because I've purchased BOTH SETS. Both include inconel studs and Stage8 locking hardware, but the TSE set included Resbond and instructions.

I've also purchased the OEM Nissan 8mm studs when I put together my SR20 & FM downpipe elbow. If they are actually inconel, I'd be surprised.

The FR stuff is junk. If you actually ask them, they will tell you to go buy 10mm inconel from TSE. The googlemachine will also show you that the 10mm TSE product is being used by A LOT of people, not just in the Miata community.

Since this thread brought out that the Full Race 10mm (and 8mm for that matter) studs are indeed not Inconel™ but rather something called A286 I became dismayed thinking that I would be subject to a possible future failure. EO2K says they are junk. BBundy says they are no better than hardware store studs. Those guys know a whole lot about everything so that scared me quite a bit. So I did a little research to determine exactly what I did buy.

Inconel™ is a stainless steel alloy with the name trademarked by the Special Metals Corporation.

A286 is also a stainless steel alloy. It is also known by the trademarked name of Incoloy™, also held by the Special Metals Corporation. Interesting.

So how do the two compare? They differ in their percentage of nickel and one of the two contains titanium and there are some other differences.
Here are some interesting charts for you science-y types on the two alloys:
https://www.miataturbo.net/attachmen...ine=1424886287

https://www.miataturbo.net/attachmen...ine=1424886287

I don't know what to think so you guys help me out with deciphering what I am seeing.
I am not a mechanical engineer.
Am I safe? Am I good enough for now? Should I be worried? Should I be hocking mine and start hawking some Inconel™ studs? Should I downgrade to non-Inconel™ nuts? Should people receive warnings for mentioning tires they bought at Tire Rack since Phil's Tire Service is a site sponsor and Tire Rack is not?
I have many questions that need answering here. Please help!

a286 is a high temp grade of SS. inconel is not a SS, although many people and places(even the people who invented the stuff) will say it is. in order to be classified as a steel, the primary alloying element has to be iron. any true inconel's primary alloying element is nickel.

a286 is not hardware store junk, it is a few notches above, but its not quite inconel either.

also, the issue is creep, specifically with the stud/bolt. to my knowledge the nuts threads dont creep, nor has anyone made or sourced inconel nuts to my knowledge. i dont know why you are so concerned with the nuts being inconel, but they neither exist or are required.

my opinion, for what its worth, if you arnt having any problems then dont fuck with it?

compare and contrast material properties, i love this site
http://www.makeitfrom.com/compare-multiple/

750x (which is what im making my studs from)vs a286
http://www.makeitfrom.com/compare/UN...ainless-Steel/

Saying which graph represents Inconel and which graph represents A286 would help in telling you which is superior.

Which Inconel alloy is the TSE studs made from? Which Inconel alloy is in the graph?

Inconel is not a single alloy. There are many Inconel alloys, and they are not all created equally. They all have slightly different properties.

I can tell you that at 1200F, the second graph is about 25% weaker than the 1st (in terms of yielding). After yield, your turbo is no longer sealed to the manifold and the studs are just holding things in place for the time being. Not ideal. It all depends on the temps the studs see though. How hot do the studs get?

^This. If you find the studs aren't stretched after repeated hard track use, then why worry? To put your worries to rest, just buy the TSE kit, lol.

One thing to keep in mind is that 10mm studs will be much stronger than 8mm studs. For the same material, 30+% stronger. In fatigue, the larger studs will have a smaller advantage than that, but still be at an advantage.

TSE did not release what alloy their studs are made from to keep others from copying them. Andrew can chime in but its pretty much a broken record from here on in. TSE has track tested and found what they say is the best inconel alloy for a turbo miata. Other companies have also released inconel studs.

I'm sure other companies have tried to copy, because the TSE hardware works and others want to capitalize.

I don't think Andrew will say what alloy is used, and I wouldn't expect him to. I was just saying that in order to make a comparision of properties, you need to know which alloy Andrew is using. This will prevent false comparisons, whether it be accidental or intentional.

If I had a turbo, I would just buy the TSE studs from the beginning. Or Vband. I have enough things to worry about, and constantly checking for stretched turbo studs isn't worth it in the long run, unless your time is worthless. It's a One-and-Done solution.

It's been long enough that we no longer need to shroud our alloy in secrecy. We use this alloy to manufacture our studs.

Finally!! Thanks for releasing that, hopefully it doesn't cut into your sales too much, that would be a let down.

Thanks Sav. Given that evidence, it's undeniable that the alloy TSE uses is the only one that will never give up on track.

id love to say im going to use the 750x since matching CTEs is so highly stressed, but truth be told, its because its what was available in 5/8"x12" rods on ebay at the time i was looking.

i put together this comparison the other day to see how off it was compared to my mild steel flanges. it happens to have the closest CTE to 1018 of commercially available inconel. 11.9 vs 12

https://www.miataturbo.net/attachmen...ine=1424900291

I had to look at the post date to make sure this wasn't 2005. :facepalm:

I was literally waiting for a goatse.cx image, but this is so bad that I must invoke the Geneva convention.

In truth, a competitor only needs a sample stud and about $500 to have a lab tell him the composition. From that, the grade of Inconel would be known, and only the processing parameters would be in question.

It's been kind of funny following a thread about these on my local forum ... people saying they aren't worth it then coming back a month later saying they just broke their standard ones. Just ordered a set from TSE so that's one less thing to worry about!

Russell.

TSE ones work. No thought required. Buy them.

With a hardness and tensile test you could pretty much figure everything out.

that might ball park it, but how do you find the specific grade, especially when you have precipitation hardening grades thrown into the mix?


was savs comment deleted?

It appears it was. I'm not trying to rip anybody off or even copy, but I am innately curious about this stuff.

If you know the chemical composition and the hardness and tensile strength, it's not hard to guess the processes they used. You can probably take it to any heat treat shop and they would tell you what you need to do to get the same strength. TSE protects themselves, really, with quality service more than anything else. I’ve never ordered from them yet, but I’m sure I will eventually. I’ve only heard great things about them.

Also, not all inconel is created equal. Inco 600 is barely stronger than any old stainless. 625 is leaps and bounds stronger. 718 is gnarly nasty tough and strong, but immensely difficult to machine. Cutting threads in it would be difficult and require support like a steady rest on the other side of the cutter because the cutting pressure is so high. It’s really hard to take fine cuts in 718. I’m not really familiar with the other grades of inconel. Then there are other superalloys like hastalloy-X, waspalloy, etc.

You wouldn’t want an Inco nut on an Inco thread because it would gall like crazy.

THIS is how TSE really protects themselves. Recommendations from legends, and a quality functional product.

thats what was being discussed, not the machining or post machining processes. im not even sure the the TSEs are heat treated.

special metals has a great set of documents for inconel, including a work hardening chart for the various grades. another reason i chose 750x is because its work hardening curve closely approximates 304 SS. my guy said he can do 718, but he really didnt want to.


ill also put my disclaimer, not trying to figure out what the TSE stuff is or rip andrew off. im going to make my own no matter what. this is for science.

the graph on pg 1
http://www.specialmetalswelding.com/publica/Mach.pdf

Pretty much sums up trying to get something made of 718 lol.

He'll go through cutters like crazy, and trying to hit a tight tolerance is really hard because it's really difficult to just take 1 or 2 thousandths off.

Having run a CNC machine for a handful of years I can confirm. Its a mechanically great material but it sucks ass to cut it. I ended up working with my Kennametal sales guy to find cutters that could do the job without blowing up all the time. The trick is finding a shop that has experience with this type exotic materials. Its not exactly a "job shop" kinda thing

Exactly. Buy something proven and move on. I'm starting to discover my time is not as worthless as I originally thought. I see no reason to reinvent the wheel.

IIRC, TSE has the threads rolled, which is another plus. No question, there is no reason to go somewhere else and it maybe will work. Choices are TSE or V-Band.

I have closed this thread. If you guys want to continue discussing what Inconel TSE uses, you can take it back to the giant thread we already have.