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Old 09-29-2009, 12:33 AM   #801
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I was just coming up to your level man, you are the one with the all the degrees and the knowledge here? I'm just a pathetic scribe. I figured using all that high flutin langauge that you upper level beings use all the time would put you right at home.

Knowledge is knowledge and numbers are numbers ok man? No one cares about your degree. I've got 5 of them. They are still sitting in the envelopes that they were sent in...

Actually my CFD did account for convection, plug flow, laminar flow, ahh to you engineers you know the difference, and how that effects the coefficient of heat transfer. I wouldn't know anything about all that.

So what you want everyone to do is instead of using what the rest of the world uses... numbers... you want us to go out and try every single piece of steel and from that knowledge select the right one.. Wait, that would take a long time? How about we use numbers?
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Old 09-29-2009, 12:54 AM   #802
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You asked how I made My recommendation,thats how.Thats all.You dont need to test everything,I did it for you.My research has become part of the info that you have used to come to your decision,my numbers are property of NMSU.Idont mean to be rude,if I have been...my bad.So...You did your research, now go break something,and if the results match your cfd, cool.If not jet engineers Know more than we all do.
-G-
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Old 09-29-2009, 12:59 AM   #803
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Originally Posted by gospeed81 View Post
Yes, yes, no, sure are, and yes.

Not guessing. My money is on Sav (well, if you insist on holding up a turbo AND sealing the flange with only 4 bolts then my money is on Sav).

But since Travis came out with his top secret material selection I decided to check (as it sounded familiar) and sure enough, we've sent out a few orders of it.

When I'm at work Friday I'll look into it a little more. Regardless, we likely don't just have the size and material we need sitting on a shelf...and even if it was I don't do the five-finger discount thing.

They would have to be made...but I'd tell sales they were full of **** if they wanted $25 a piece for 'em.
I too support Sav. in this one,even tho he was mean to me once.
-G-
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Old 09-29-2009, 02:07 AM   #804
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Travis, two things:

One, you talk about the best material. After looking through it, A286 probably is a better material. At the same time, the BEST solution would be to cast the housing and manifold together. Why don't we just do that? Because it's EXPENSIVE. If you break something, the cost is $800 vs. $400 to replace one piece or the other. If Inconel 690 or 706 or 903 or whatever else does the job, and A286 does the job but it's twice as expensive, then...

Secondly, on your thoughts that Inconel is the wrong choice:

Quote:
Originally Posted by JKav View Post
Inconel exhaust studs are a known solution.
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Old 09-29-2009, 02:15 AM   #805
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I too support Sav. in this one,even tho he was mean to me once.
-G-
It's a rite of passage
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Old 09-29-2009, 02:38 AM   #806
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It's a rite of passage
I know.-G-
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Old 09-29-2009, 08:53 AM   #807
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Quote:
Originally Posted by TravisR View Post
I think anyone with simple math can look at the numbers and tell which material is superior.
There is no SUPERIOR material...only a proper material for the application.

This is my whole problem with this thread: We are convinced there is a magic bullet material solution.

It's a DESIGN problem. Material selection is only a part -albeit an important part- of the design process. We don't know the first thing about what kind of stresses these studs are going through and why they are failing (Greg might).

Ok...so this stud failed...and this one's stronger...so it should work right? WRONG.

Why did the other stud fail? What was the max principal stress? What was it's orientation? Can we change the geometry? Can we change the loading method?

After you've done all that you select your material.

Stronger material better right?

WRONG once again noobs.

A "stronger," "stiffer" material actually sees higher stresses under the same load. The only analogy I can offer goes like this: "The tree that doesn't bend will break."

A tree trunks job is to hold up the branches...and to stay in one piece for biological functions. It doesn't have to stay straight within 3* or anything special...just hold up the leaves and stay in one piece. So when the wind blows...IT BENDS.



Sav hit the nail on the head talking about plastic deformation. You want a material that doesn't exceed it's elastic range for the given loads. However, if you are still above the stress limit for inconel, it will actually deform sooner!

Truth is, once again, we don't know what kind of loads we are designing for. Therefore we can't dream of knowing when an M8 Inconel/A286/Atomantium stud is going to fail, and in what manner.

All we are doing is throwing random materials at a problem we have no design control over. One may work...many may fail.

Since no one has stepped up to do a real analysis of the whole hotside system (I'm assuming Travis just looked at the flange system itself), then I don't blame Sav one bit. Sav and crew hit the track enough that they may have a solution that holds up in a matter of months. I honestly wouldn't hope for any "engineered" solution from BEGi or the like in anything less than a year, unless Travis actually found the heart of the problem over this past month. I do know that Travis's work on the thermal loading aspect may pay off. The CTEs are important or you will be using the flange to work against the fasteners.


If you ask me though...you must look past the flange. Four mild studs will hold ~30psi, 15lbf shear, and a ~10ft-lb bending moment at 1000*F all day long. That's what you see if you look at just the flange, and only consider the two parts that make up that mating surface.

The downpipe, +1G sustained cornering forces, and engine vibrations are all wreaking absolute havoc on such a simple analysis though.



I apologize for not knowing more about this problem. Fact is I don't have it, and haven't been fortunate enough to hit the track and either experience it myself or see others endure it.

All I can say is that there is more to the problem. Good luck finding a material to fix it.

I do think that there aren't enough solutions out there simply because most vendors think they'd never get away with selling $150 stud sets. Considering most of the track guys here can spend that much on a single day, or a set of brake pads that might last a month...they would just be lazy to not invest in good hardware.



Now we just have to define good hardware.
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Old 09-29-2009, 09:00 AM   #808
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Ok...read the last couple of posts by Sav and Greg.



I seriously hope this is the fix.
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Old 09-29-2009, 09:29 AM   #809
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Quote:
Originally Posted by Reverend Greg View Post
I quess I can let The cat out of the bag here,I have my "welding"degree In Materials Technology.I wrote my senior Paper on Nickel alloys.
-G-
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Originally Posted by gospeed81 View Post
epically accurate summary
bitches be sandbagging
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Old 09-29-2009, 09:30 AM   #810
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Quote:
Originally Posted by gospeed81 View Post
There is no SUPERIOR material...only a proper material for the application.

This is my whole problem with this thread: We are convinced there is a magic bullet material solution.

It's a DESIGN problem. Material selection is only a part -albeit an important part- of the design process. We don't know the first thing about what kind of stresses these studs are going through and why they are failing (Greg might).

Ok...so this stud failed...and this one's stronger...so it should work right? WRONG.

Why did the other stud fail? What was the max principal stress? What was it's orientation? Can we change the geometry? Can we change the loading method?

After you've done all that you select your material.

Stronger material better right?

WRONG once again noobs.

A "stronger," "stiffer" material actually sees higher stresses under the same load. The only analogy I can offer goes like this: "The tree that doesn't bend will break."

A tree trunks job is to hold up the branches...and to stay in one piece for biological functions. It doesn't have to stay straight within 3* or anything special...just hold up the leaves and stay in one piece. So when the wind blows...IT BENDS.



Sav hit the nail on the head talking about plastic deformation. You want a material that doesn't exceed it's elastic range for the given loads. However, if you are still above the stress limit for inconel, it will actually deform sooner!

Truth is, once again, we don't know what kind of loads we are designing for. Therefore we can't dream of knowing when an M8 Inconel/A286/Atomantium stud is going to fail, and in what manner.

All we are doing is throwing random materials at a problem we have no design control over. One may work...many may fail.

Since no one has stepped up to do a real analysis of the whole hotside system (I'm assuming Travis just looked at the flange system itself), then I don't blame Sav one bit. Sav and crew hit the track enough that they may have a solution that holds up in a matter of months. I honestly wouldn't hope for any "engineered" solution from BEGi or the like in anything less than a year, unless Travis actually found the heart of the problem over this past month. I do know that Travis's work on the thermal loading aspect may pay off. The CTEs are important or you will be using the flange to work against the fasteners.


If you ask me though...you must look past the flange. Four mild studs will hold ~30psi, 15lbf shear, and a ~10ft-lb bending moment at 1000*F all day long. That's what you see if you look at just the flange, and only consider the two parts that make up that mating surface.

The downpipe, +1G sustained cornering forces, and engine vibrations are all wreaking absolute havoc on such a simple analysis though.



I apologize for not knowing more about this problem. Fact is I don't have it, and haven't been fortunate enough to hit the track and either experience it myself or see others endure it.

All I can say is that there is more to the problem. Good luck finding a material to fix it.

I do think that there aren't enough solutions out there simply because most vendors think they'd never get away with selling $150 stud sets. Considering most of the track guys here can spend that much on a single day, or a set of brake pads that might last a month...they would just be lazy to not invest in good hardware.



Now we just have to define good hardware.

I've done the complete analysis.

Very plainly I found the expansion of the flanges because of temperature variance in the part. Then I calculated the strain on the fasteners at the extremes caused by the unequal expansion.

2 parts here:
  1. part is that the studs were not getting heat because of the high thermal capacity of the flange. Heat moves pretty slowly through the flange so the fasteners can't heat up.
  2. Because the fasteners can't heat up they are not expanding at all at first.

I calculated the stress on the studs from that. At that point I had found large expansion loads put on the flange by unequal heating and set my number one parameter on high CTE materials. Unless the materials would expand easily from any amount of heat their loads would be too high for even the best fasteners to work well. Thats when I found this mysterious 660 grade stainelss which i thought would be incredibly good for the job. Its used in turbines, its used in high heat situations with high loads.

The next parameter I was looking for was high heat strength. Something that stainless steels do not have. At first I was looking at 316Ti, the titanium stabilized version does have better strength, but not that much better. 660 though has the freak property that I was talking about with the high heat strength as well.

So I calculated at a maximum temperature of 1200F* what preload range I would need to not exceed plastic deformation. Then I calculated to see what preload range I would see under maximum thermal strain when at around 400F* where my calculations put me at maximum transient. This also did not exceed the proportional range of the material.

Good, so the next step was to use S/N curves to see if at that loads I was seeing will the preloads seen in the joint cause fatigue failure, and found that they will not.

The final thing I looked at was joint stiffness. I was going to calculate the loads of the turbine, but then decided I really didn't know the G-forces seen on the turbo and the effects of the piping as a brace, the strength of the flange itself. It would be too complicated, under my preload it should be "fine" althought not technical thats the part that really ahs to be tested.
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Old 09-29-2009, 10:14 AM   #811
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Sorry Travis...just used your quote to make my point for the direction of the thread.

It's good to know you did a pretty in-depth analysis (certainly MUCH more than I'm willing to do).

I will say the last customer that ordered that material used it for a very high pressure/high temp flange application, but I don't know about the loads, static or dynamic.

Hopefully we can hook you up...
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Old 09-29-2009, 11:23 AM   #812
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Quote:
Originally Posted by Savington View Post
Travis, two things:

One, you talk about the best material. After looking through it, A286 probably is a better material. At the same time, the BEST solution would be to cast the housing and manifold together. Why don't we just do that? Because it's EXPENSIVE. If you break something, the cost is $800 vs. $400 to replace one piece or the other. If Inconel 690 or 706 or 903 or whatever else does the job, and A286 does the job but it's twice as expensive, then...

Secondly, on your thoughts that Inconel is the wrong choice:



I completely agree with your point, the best design does the job, and does it the cheapest out of all the options. I have not done an indepth analysis on all the inconels like I have the A286. I just don't like the normal CTE numbers I see out of inconel, and stopped there. i have a feeling the inconel hardware will work for a couple years before it breaks because it is a high temp material with much higher proportional limits then most. That is given that it was calculated to preload properly, if you over torque it its going to stretch just like anything else. I believe A286 is the uber solution that will last forever, but there could be other materials out there that are cheaper and do the same.

My point is that if we can get A286 for the same price as your kit then why wouldn't you use it? That is yet to be seen though.
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Old 09-29-2009, 11:34 AM   #813
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As much as I would love to see photos of you all comparing the length of your penises, why dont we just chill the F out until everyone gets to test their personal favorite solution?

Savington and his inconel
TravisR and his A286
BEGi and I forget
gospeed and his cheaper A286?
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Old 09-29-2009, 11:38 AM   #814
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Originally Posted by y8s View Post
As much as I would love to see photos of you all comparing the length of your penises, why dont we just chill the F out until everyone gets to test their personal favorite solution?
I don't like your tone!
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Old 09-29-2009, 12:32 PM   #815
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Originally Posted by y8s View Post
As much as I would love to see photos of you all comparing the length of your penises, why dont we just chill the F out until everyone gets to test their personal favorite solution?

Savington and his inconel
TravisR and his A286
BEGi and I forget
gospeed and his cheaper A286?
Problem is that Travis, Begi, and Gospeed can't correctly test their solutions. Travis and Gospeed don't track, and Begi can't drive a car hard enough.
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Old 09-29-2009, 04:27 PM   #816
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Originally Posted by y8s View Post
Savington and his inconel
TravisR and his A286
BEGi and I forget
gospeed and his cheaper A286?
BEGI is testing Monel studs. Same material the turbine wheel is made of.
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Old 09-29-2009, 04:53 PM   #817
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Quote:
Originally Posted by y8s View Post
As much as I would love to see photos of you all comparing the length of your penises, why dont we just chill the F out until everyone gets to test their personal favorite solution?

Savington and his inconel
TravisR and his A286
BEGi and I forget
gospeed and his cheaper A286?
Yeah, let's also forget that my 304 solutions has already PROVEN itself ON TRACK over multiple events, with NO issue and SUB SM LAP TIMES.

You all keep moaning about your unobtainium while comparing genital lengths.

Amen.
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Old 09-29-2009, 04:54 PM   #818
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Saying Travis didn't do an in depth analysis is just plain silly. Anyone with any engineering training or has even seen engineers on TV would know he looked at it pretty carefully. It'd be almost as much work to fake that sort of knowledge as to do the simulations and research.

Greg, just because you saw one good material, that precludes any other material from being good? That's just silly. It's a logical fallacy.

Sav hasn't tipped his hand? I.E. His material is still a secret?

We (those who are paying attention) all know whatever we use needs to not deform plastically under use, i.e. during transients and steady-state (there's got to be a load of the exhaust sitting somewhat still while the motor tips over on it's mounts). To know this, you DO need to know the CTE as a function of temperature, and to know what the temps are of the various pieces as a function of time. Travis claims to have done this - now I can't know if he did a good job, but it sounds a long ways off from bullshit.

I am a bit concerned that inconnel will hold up in the long term, but really the two smartest answers are:
1) Everyone chill till we find out what price the 286 stuff will end up costing. I'd get a set if they were M10's and cheap, but my studs have been perfect ever since I'm upgraded to McMaster's finest. :-) If Travis really wanted to be convincing, he'd do the same analysis to see how many cycles (you guys DO understand that's what he looked at, right? To see how much use it can get before failing) with the other materials and see if there is a significant difference. If GoSpeed can find these/make these cheap, then it's a done deal, and hopefully Sav doesn't take a bath.
2) Duh, there is no requirement everyone use the same thing. Y8s speaks softly and carries a big stick of logic.
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Old 09-29-2009, 05:11 PM   #819
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Originally Posted by crashnscar View Post
Problem is that Travis, Begi, and Gospeed can't correctly test their solutions. Travis and Gospeed don't track, and Begi can't drive a car hard enough.
Geez... Did I tinkle in your Wheaties today and not know it?!?!?

I know, I know... you have said several times BEGI can't test or design anything right. However, I think we are smart enough to know when someone else has to test it first. Obviously, in this case, because we don't have a dedicated track car. So, Corky and I have two dedicated track cars lined up to test those bad boys out. Perhaps you should spell out what the "crashncar criteria" is for "correctly tested" means. So that we don't disappoint.

"BEGI can't drive a car hard enough". Hey... I've learned my lessons after blowing two motors and a couple of collisions.
Or perhaps 18 years of SCCA/IMSA racing, by Corky, isn't good enough for you. (I am rolling my eyes now)
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Old 09-29-2009, 06:21 PM   #820
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Quote:
Originally Posted by Stephanie Turner View Post
"BEGI can't drive a car hard enough". Hey... I've learned my lessons after blowing two motors and a couple of collisions.
Or perhaps 18 years of SCCA/IMSA racing, by Corky, isn't good enough for you. (I am rolling my eyes now)
Stephanie
I'm certain that Johnwag and myself will gladly compete in a racecar you've prepped in NASA TT or RLT next season. We've learned a lot this season...I know I've spent more than enough time under and inside a certain competitors car.
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