Dude, did you read what I wrote? I said there are more builders with many more hours of experience using 993 Twin Turbo Dilivar head studs than there are using Supertec studs. That is the empirical data I am talking about. You are the one that wanted to play the empirical data with years of experience game and I happy to do so. I was referencing usage rather than ovality.

Winders,
Why do you feel the need to change someone's opinion on this topic? Your opinion is yours, your welcome to have it. But returning to this effort of defending your opinion over, and over with such conviction just makes me ask WHY.

In a thread dedicated to the question "why close a thread" some people can't help but illustrate why.
This thread is not about head studs. It's about the need for a moderator to step in.
boyt911sc nailed it.
Obsession...........

In an earlier "head stud" thread, Winders touted Aaron Burnham as an expert that used Dilivar in his builds....Now that Aaron is challenging the "religion of Dilivar", Winders can't help but "call him out".
Obsession "to be right" mixed with a healthy dose of "but what about the cool kids"

Here's a little heads up: Aaron has a great wealth of actual knowledge/experience that he is willing to share. Challenges from the "clueless, let's silence dissent crowd" is destined to chase him away. To the asshat who questioned whether he's an engine builder: Aaron builds great engines....I've watched him do it.

Come after me, I like winding the top and watching it spin into the ground.

You must not have read my post Scott since the point of my post was Squirrel's lack of data and his thread can be interpreted to mean bore distortion is a real an issue. You decided to jump in and advance another argument. Stud choice is an engine builder's personal preference and run what they have had success with. I don't have a real problem with running that stud, but why should use them? The expansion rate theories are particularly nebulous and in the end we cannot find strong evidence that the added cost is worth it. Henry has found evidence that they don't control the head as well as he would like and does not like them. I can respect that. You have taken umbrage with Henry's opinion about the Dilivar stud and apparently want to force the man to not state his opinion.

Can we hear more about the "Marginally reduced failure rate"?

"...reinvented the Dilivar. This time with an all thread monstrosity that offered a slightly more aggressive clamping force and marginally reduced failure rate."

Also what is the best lube to use on through bolt o-rings? http://forums.pelicanparts.com/support/smileys/wat5.gif

This went down the toilet..... lol

My hope is that we can all post our opinions, and not get butt hurt by other's differing thoughts. ON EVERY TOPIC in this forum. We don't always need to be "right" 100% of the time. If we believe in our experience and the products we use we can post it. Our experience should not be called in to question. It is our experience and there is no way you could question it unless you were there gaining that very same experience over the years it took to create it. If you think you know better, put your thoughts into practice and prove that your new found experience yielded different results from your antagonist.... :) Then, we will all learn from your actual experience too. We all learn all the time, unless we always think we "know" better....

Chill out and relax about someone's experience that doesn't jive with what you "learned" online. Do some testing yourself, then you can actually form a valuable "opinion".

People who always want to call others out are what ruin these forums. Again, not a single person posting has to be "right". They stop experienced people from posting and sharing thoughts that may be valuable to a first time engine builder.

The most sad part of this whole $hit show is this. I am pretty sure all of the conflicted parties could sit around a table and share a few beers discussing the energy and enthusiasm they have for this passion. All would get along with only food and drink in front of them instead of a keyboard....

Cheers

Funny. My only point all along has been that the 993 Twin Turbo heads studs are a solid viable option for those looking for head studs that work and work well. I have not negatively criticized any head studs in all of my posts. Empirical data is on my side on this one. Yet it is okay for certain people to tell me my thoughts are worth nothing since I have no experience building Porsche air-cooled engines.

Then you come on and say:

Chill out and relax about someone's experience that doesn't jive with what you "learned" online. Do some testing yourself, then you can actually form a valuable "opinion".

The idea that "valuable" knowledge can only be gained through experience is ludicrous. I don't need to build Porsche air-cooled engines to obtain valuable knowledge about the parts used to build those engines. I don't need to do testing. I can gain knowledge from the experience of others.

Let me tell you a story:

When I decided to build a high output race engine for a PCA GT3 class car, I new I needed help. I needed to find a person to design the engine for me. The information I needed to put together the kind of engine I wanted to build was not available for free on the Internet. The people that had the information I needed weren't going to just give it away.

After doing a lot of asking around who would be a good choice for helping me with my engine project, William Knight's name kept coming up. Long story short, William designed the engine and sold me most of the parts for the build. I was having a person local to me actually build the engine.

When head studs came up William wanted me to use 993 Twin Turbo Dilivar head studs. After reading all the terrible things said about Dilavar here on this forum, I had a problem with that recommendation. After all, all Dilivar head studs are doomed to fail, right? William insisted...and kept insisting. So, me, being a "trust but verify" kind of guy, started researching head studs. I checked with engine designers of similar caliber to William or people that had engines designed by engine designers of similar caliber to William to see what head studs they were using in engines similar to mine.

What did I hear from just about everyone I talked to? They used 993 Twin Turbo Dilivar head studs. Not a soul said they used Supertec head studs. A few people said they used ARP studs and a couple people said they used "proprietary" studs and did not want to divulge where they came from.

Anyway, I came away from my research project with new information from many experienced sources that did not jive with the information I had received here. There were just too many experienced engine designers/builders out there using 993 Twin Turbo Dilivar head studs and happy to do so for me to go against William's recommendation. After completing my research, using 993 Twin Turbo Dilivar head studs in my engine build ended up being a no brainer.

Since this thread has devolved back into a head stud debate, I'd like to share an anecdotal experience of my own. This is about engine component choice in general, nothing specific.
I used to have this friend that wrenched on/restored Ducatis. He was known internationally, and guys would ship their bikes to him for service. One day I was out at his place while he was building a hot rod 900SS motor. This was back in the 90's. so my recollection is spotty... Anyway, I recall asking him why he wasn't using the latest widget I had read about in his build. I design engines for GM, and at the time I was in the Advanced Design group. It was my job to invent things, remove mass, push envelopes, all in the name of improved performance, increased durability, and/or cost reduction. I couldn't understand why Gregg would leave potential performance gains on the table. And then the penny dropped... At my job, I had engineering and analytical support. Lots of it. More importantly, I wasn't writing the cheques. Like any really good mechanic, Gregg stood by work. If he built an engine that failed, he ate it. The point is: why would he -or any other engine builder- take on the risk of an experimental component? Maybe that widget would have yielded an extra couple of horsepower. So what? Unless the client's name was Casey Stoner, he wasn't going to be able to use that additional power.
That's not to say that Gregg wouldn't eventually use said widget. He just wouldn't do so until there was enough data in the community to support it.

As for 993 head studs, I have to disagree with Henry. I would call a fully threaded head stud an abomination. And I'd bet next month's pay cheque that there was no engineer at Porsche pounding his fist on the table hollering, "We MUST use a fully threaded stud, because it's BETTER!!!"
That conversation much more likely went, "Yah, I know it's ugly, but it meets our Bill of Design... And it'll save us six bucks an engine."

And I'd like to add that I have a huge amount of respect for anyone willing to take on the task of developing and manufacturing ANY component with the goal of improving these engines. It's a high risk endeavor, and I doubt there's any real money in it. Those that do it can almost only be doing so out of passion.

Actually, we agree almost completely. You use the word "abomination" and I use the word "monstrosity" for exactly the same reason. No engineer would call out an "all thread" design as a performance enhancer. I think before Porsche, the most high tech use of all-thread was the gate hinge on a rodeo bucking chute.
You also postulate that the Dilivar stud had a financial component. I believe that financial component was a warranty issue but there you go.
The all thread design also had a structural component. Not performance but survival. As noted in decades of Dilivar failures, the material is susceptible to environmental influences. Dilivar corrodes and fractures under stress. Instead of using a corrosion resistant material they chose to mitigate the environmental effects with coatings and surface forging created by thread rolling.
As for the testing component: We tested our studs in both racing and high mileage street application for 5-6 years before offering any sales to the general public.
Let's review.
A clean-sheet stud design that makes sense (ease of assembly, more consistent torquing numbers, using the highest quality, fine thread, 12 point nut), using a material that resists environmental influences and offers a clamping force more in line with the engine designers original intent.
Hmmmm, where would you find such a stud?

My "disagreement" with you, Henry, was entirely tongue in cheek, but I think you know that...
I am, incidentally, about to undertake my own 3.0 engine rebuild. I just need to get a few last minute ducks in a row in the garage before getting stuck in. I'll be using your head studs, but I'd also like to chat with you about your 3.1 option if you're still offering it...

I believe we discussed how the use of the rolled thread provides closure of the exposed Dilavar grain boundaries to eliminate stress corrosion failures. That thread is here:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/1087450-cylinder-head-clamping-bore-distortion.html


[QUOTE=You also postulate that the Dilivar stud had a financial component. I believe that financial component was a warranty issue but there you go. The all thread design also had a structural component. Not performance but survival. As noted in decades of Dilivar failures, the material is susceptible to environmental influences. Dilivar corrodes and fractures under stress. Instead of using a corrosion resistant material they chose to mitigate the environmental effects with coatings and surface forging created by thread rolling.[/QUOTE]

I believe the choice is to allow excessive clamping force to distort your cylinder bores, or to find a solution to that problem, and then solve the stress corrosion issue associated with it. Porsche did the later. You do the former.

[QUOTE=As for the testing component: We tested our studs in both racing and high mileage street application for 5-6 years before offering any sales to the general public. [/QUOTE]

Maybe so, but Dilavar has won Lemans outright on 15+ occasions. I think I'm going with Dr Metzger on this one.

https://christophorus.porsche.com/en/2019/390/le-mans-1970-hans-mezger-17083.html


[QUOTE=Let's review.
A clean-sheet stud design that makes sense (ease of assembly, more consistent torquing numbers, using the highest quality, fine thread, 12 point nut), using a material that resists environmental influences and offers a clamping force more in line with the engine designers original intent.
Hmmmm, where would you find such a stud?[/QUOTE]

Why would you want to find such a stud when a superior alternative that doesn't produce excessive clamping forces on thin aluminum cylinders exists?

Finally, it's DILAVAR Henry, not DILIVAR.

Back in the day, "Dilivar" was one of several counterfeit studs sold to unsuspecting customers (Porsche repair shops, retailers and dealer parts depts. too). I believe another was "Dilvar". Most were magnetic (regular steel).

Scott, I did not say that valuable knowledge can be only gained through experience. You are putting words in my mouth. I said actual experience should not be discounted. It is experience, after all. The same way you do not want the experience of the people you talked/emailed with discounted. It is their experience, after all.

Relax, it is not a contest.... No one has to be right. We are all trying to relay our experiences. Relay yours, and if that is research, so be it, as that is valuable too. Then let the reader learn and make a choice.... You don't always need to tell people they are wrong about what their experience has taught them because you know of contradictory opinions/experience. I really don't care if people agree with the thoughts/tips/advice I post. I post it, if it is valuable to one person or no one, its all good by me.

I suspect you won't listen, but, please, continue to post what you have learned. It is valuable and trustworthy. And then leave it at that. It will make what you post more appealing to the readers. If you want your opinion to be heard and valued it would help... A forum is most valuable when many points of view are expressed. It gets devalued when it always turns into a bun fight.

Its like trying to win a DE.... No trophies here and no pretty girls to kiss on the podium.....

Cheers

Jeff,

I am not putting words in your mouth. You wrote:

Do some testing yourself, then you can actually form a valuable "opinion".

That sentence is pretty clear. If I don't actual test something myself, I can't form a valuable opinion. That means without experience my opinions, based on the knowledge I have, are not valuable. So, if that is not what you meant to say, be more careful with your words.

As far as this head stud things is concerned, I mention 993 Twin Turbo heads studs as studs that work and work well. Henry says they suck. I say they don't and he says they do. I back it up saying where I got my "knowledge" and Henry says I am some disciple listening to the "cool kids" and because I have never built an Porsche engine my posts mean nothing.

Yeah, I am going to keep quiet after that crap.....

Scott, an opinion formed on experience is different from research. You are relaying what others think. Which is fine, you have access to them at more frequent rate it would seem than the rest of the forum members have. But it is their opinion.... You may agree with them, and that is all good.

Surely, you can understand that.

You said "Yeah, I am going to keep quiet after that crap" lol. That is because you still think it is a competition. Why? You have a nice racecar, have likely achieved success in some other walk of life to be able to afford it, so relax. There is nothing to prove here. You don't seem like a silver spoon sort of guy, so you have nothing to prove here. Post your thoughts and opinions, refrain from the constant arguments that you have to prove someone else is wrong.....

Scott, the intelligent people who read the forums can separate the BS from the fact. You don't need to spoon feed them all the time to prove that YOU THINK YOU ARE RIGHT.

But, it is pretty clear you have no value for any opinion that differs from yours. And, because you have to win, you must call out that opinion and make a big fuss. Like I said, the people who are actually going to gain from the posts, regardless of the position/opinion, will see through the playground infighting and make an informed choice. It doesn't matter if it what you think is best.

Like I expressed in the past, I have ZERO F$CK$ to give if people don't take my advice/thoughts. It really doesn't hurt me. What bother's me is certain people who continually destroy forum posts because they always need to win or be right. It is a community, respect the fact that we can be members of a passionate community, like most of the others do.

Thank you for your technical contributions to the forum. People may, or may not, value them less because of your approach. If they value them less because of your tone and delivery, posting them becomes a waste of your time as a contributor to the Community. But if doing so, makes you feel good, continue on...

Cheers

Moderator.......
 

This thread is getting worse than the other thread you CLOSED. Time for a cool down.

Tony

Don’t we have a PARF section?

Wow, more hero worship.
I guess by this answer, you believe that Porsche engineers never make mistakes?
You think the 2.8/3.0 RSR engine was the same as the engine offered to the public.?
You think the RSR used magnesium cases?
You think the heads were the same as a 2.7 or 3.0?
You think the cranks were the same?

Do you believe that the later 74.4 cranks offered to the consumer was a "great" crank and rod design? No room for improvement? Do you believe that ARP bolts are a major improvement over Porsche rod bolts in these engines?
Do you believe that the cranks in Porsche race cars ever use the 55mm rod journal found in production cars?
How do you feel about the rod length to stroke ratio offered in production 911 engines. In most Porsche engines, it sucks.
Most people who understand these basic concepts understand that engines are built with compromises....even Porsches.
As these flaws start to materialize, innovative engine builders seek to push the envelope with design improvements.
Tensioner arms, rockers, rod to stroke ratios, head studs, rod bolts, compression ratios, cam profiles all deviate from the long held production precepts to produce a longer lived and much improved platform for the Porsche driving experience.

Actually, putting words in other peoples mouths, introducing straw man arguments and pitting one group against another is really all you bring.
When asked the question "why use Dilavar" your answer is consistently "because these guys all use them and they can't all be wrong". Maybe not but never once have you offered an argument based in science. Your argument is always conjecture, urban legend, internet belief and hero worship.

hey, so I'm back and now I've got the motor apart, trying to find a supplier with stock who answers the phone and can get me some head studs. I'm leaning towards the Supertec studs but our host says they are out of stock and can't give me a firm date when they could supply them to me. Need a few other parts, but for the most part the motor looks very clean.

Any suggestions for an in-stock head stud that will hold up to my 3.6 application?

If you want to use the SuperTec studs, call Henry.

I am sure you can get the 993TT studs from Sunset pretty quickly.

This Henry:

Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net

Not to take any business away from Henry or Pelican, but if you come up empty, I have plenty of our Stud kits in stock.

Gave up on phone calls and emails to Henry, pelican was back in stock, so I ordered all the bits I needed and a 10% discount helped bring the price down to what I would have paid to buy direct from Henry. Thanks all.

I apologize for the radio silence out of Supertec of late.
As a hands on owner/operator, I was absent due to a prolonged Covid hospitalization.
We are restructuring delivery systems to ensure that services, parts and information are less "Henry" dependent.

That said, 993TT Delivar studs an inferior/ ridiculous design and I wouldn't use them in a stationary generator.

Here we go again....

You don't have to use them....but to suggest the 993TT studs are somehow "inferior/ridiculous" is, in itself, ridiculous! There are just too many high output race engines architected and built with them by respected people to take your position seriously. Just ask William Knight. He designed my 431HP 3.6L race engine and he spec'ed 993TT head studs...and he knows about yours.

That was easy........

it's all semantics, but putting this thread back on track, I'm happy I was able to get the Supertec studs. Was hoping to buy them direct, but Covid got in the way, sorry the team at Supertec had been so severely affected. Still, our host has them for only a little more money and was able to supply me with most of the other bits I needed, combined with a PCA 10% discount, I did ok.

I'm always happy to support the little guys, and appreciate the help I got from Henry on my '72 2.7 RS MFI/twin plug build recently. It gives me great peace of mind to know I won't have to worry about head studs on the 3.6 ever again.

Mercedes F1 completely dominated the Formula One championship with innovation for nearly a decade.
Every engine manufacturer from Ferrari, to Renault, to BMW, and Honda all used their "we've done it for years" mentality to simply survive.
Porsche engine builders in many situations are guilty of the same complacency.
Every time someone says "But these guys do it" they ignore the opportunity to achieve an even higher level of excellence.

Is that directed at me?

The people I know that use 993TT head studs don't use them just because Porsche does. They use the 993TT head studs because they work in their engines when other products did not.

I know they are working quite well in my high compression high output race engine. The 993TT studs were used in my engine because the guy who designed my engine, William Knight, said to use them.

If you don't know by now, I don't just take someone's word for something if I don't understand something. I had been reading for years on here about how terrible Dilavar was as a head stud material. Mostly from you. Pelican is just a microcosm of the Porsche world. So, I decided to do some research to see if William's choice was sound. First, I talked to William about it. Then, I talked with several race engine builders I knew and trusted. To a man, they all said the 993TT head studs were the way to go. No one said I should use Supertec head studs. No one said anything negative about Supertec head studs, but no one mentioned them either.

I am sure that your head studs work great. But that does not mean that the 993TT head studs don't also work great. Your massive bias against dilavar prevents you from having anything close to an open mind on this issue.

The idea that your are Mercedes in your example is hilarious!! If someone wanted a high output race engine built to beat the competition, your name isn't even on the list of builders one would go to....

It's absolutely hysterical to watch ideology conflate personality with technical product assessments.

Comedy gold right there!

Guys as you may know I try and stay out of these threads................ But in the effort to help people have a good laugh....... Just Kidding... First an answer to GTC. I use DC 111 on all O rings. It conditions the o rings and adds a lot of life to the O rings..
Now for the head stud mystery.....
I sent a client to purchase Supertech studs last week... Look like a good product I have used one set, I do not have a lot of experience with them and on high HP builds I try and stay with what I know to work as clients do not like me to experiment on there car as a championship could be riding on it..
993 TT studs are NOT inferior at all, maybe Supertech are better maybe there not... It does not matter. I would use Supertech to support a small shop that is a Pelican member.
15 years ago I was racing an 3.5 liter turbo motor at 2 bar of boost.. I never had a problem with the 993 TT studs on a motor over 1000 hp...
Back to studs and my experience I have had problems with Raceware and ARP. I would not use either on a build that was much over 300 hp.
I have built MANY turbo motors back in the day and had excellent success with plain steel 2.7 steel studs. Montys motor made 645 HP at the wheels and ran plain 2.7 steel studs for a decade without changing them.
I hope this helps, sorry Henry had covid, I have it now and hope to be back to well in a week, about 50% better and I pray all of this craziness is behind us and we can move forward and start living again.. I am thankful for Pelican and the help it brings to people. BUT It does suck when I see talented people on this forum going at each other, William Knight

I find it interesting that Winders "master race engine architect" would believe that a production fastener designed to mitigate warranty issues (oil seepage on cool down not a performance enhancement) could not be improved upon by a design criteria that specifically targets the design flaws of this (cascade of failures) stop-gap fastener. Then to ignore the design features that by ease of repetition, would entice the builder to improve consistency of the assembly regimen. Build every engine exactly the same so slight design flaws are easier to identified. Sometimes group-think and fear of change creates a fog of complacency. Even the nut and washer design lack any semblance to situational excellence. A low quality barrel nut designed for speed on an assembly line fails "fastener 101" in engineering school.
As for the "race engine scenario" 95+ percent of all the engines built on this forum are either stock, slightly warmed over and spirited canyon cars. My advise is for those guys who really want their best chance of getting it right. That's why I'm here. 8000 posts designed to help the "one timer" get it right the first time. The suggestion that what works on the track is right for most DYI builders generally does the community a disservice.

William, sorry to hear you got the Rona as well. It's too bad your Padawan saw it necessary to bother you with this non-sense. Rest and be well.

Actually, Henry, William Knight is the "master race engine architect". I am not and never have claimed to be that. But that does not mean I can't obtain quality information from reputable sources. Also, you should note that I have never said that the 993TT studs could not be improved upon or that they were superior to your head studs. My only point all along has been that 993TT studs work and work well. Oh, and a lot of reputable high performance engine designers use them.

I guess, in your mind, high performance engine designers like William Knight, Singer, Dawe, Jae Lee, and Jeff Gamroth live in a world of "group-think", "fear of change", and "a fog of complacency". Yeah, that's how all of them got where they are....

William is being quite diplomatic in his post. But please look at this statement he made:

"993 TT studs are NOT inferior at all..."

That is counter to everything you say about 993TT head studs.

This is still sad to me, I know Henry enjoys the back and forth post with Winders, he actually told me this I am not making it up. I agree with what Winders has said and I also think he in this thread has promoted Henrys studs and said nothing negative to stir up drama. I like Henrys studs and I think all Winders was asking him to admit is that 993 TT studs are also a decent option.

Not a single engine builder you chant as the "holy grail" have been willing to do the research. On the other hand, I've built hundreds.
If any of your experts want to discuss the science/technology, I'm available. I would be interesting to have someone with an open mind to discuss the "real" issues.
Even William admits he's not willing /his customer won't let him innovate.
after selling a thousand + sets, we have never responded to negative input.
For those DYI builders looking to install a more conventional stud (using the silly nuts :et al) the Canyon stud is even superior to the 993TT.
John and I have been in the discussions surrounding stud technology for a couple of decades.

I'm not sure questioning my expertise (with less than zero actual knowledge) qualifies as "asking him to admit".
Teasing gyzmos can be greatly entertaining.
As for the request to capitulate, why?
They are not a decent option for a plethora of reasons not the least of which is the ridiculous price. 99310117054 $57.75/ea from our host.