Headstuds - would you use these?

[motley911]

Hello,
I am beginning the assembly of my 930 engine - which I purchased unassembled from the previous owner. This will be a a high HP engine with twin K24 turbos and a Motec FI system.

The PO started building the engine about 5 years ago but abandoned the project. The engine is fitted with new/never used 993 fully threaded head studs which are non-magnetic - therefore I assume they are dilavar.

Should I use these head studs, buy a set of good aftermarket studs (Raceware, Supertech, ARP) or buy some original steel head studs?




Thanks,
Richard.

[docrodg]

If you are running twin turbos at high bar and count on revving this thing up I would think that the Raceware or ARP studs would be a better choice, if nothing more than for the peace of mind they won't fail. The factory steel studs are very strong, but the more stress, the more reason for better studs.

[Henry Schmidt]

Supertec head studs are the best head stud selection for any 911 application. Race proven on engines from 2.0 to 4.0 and from 160 horse power to well over 800.
No failures ever reported to the manufacturer. Life time warranty. The only head stud designed with modern engineering practices.
All other porsche head stud designs were used to reduce manufacturing cost not to produce the best engineering principles.
These studs are in stock and available through our host, Pelican Parts at competitive prices.

http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=SPTC-HSK-1&catalog_description=Supertec%20Performance%20Cylin der%20Head%20Stud%20Kit%20(sold%20as%20a%20complet e%20set%2C%20hardware%20included)%2C%20911%2F911%2 0Turbo%2F964%2F993%20-%202.4%2F2.7%2F3.0%2F3.2%2F3.3%2F3.6L%20engines

Pelican rating:
Supertec Performance


A well-reputed high-performance engine builder, Supertec Performance has a place in the industry as one of the best for Porsche race prep and overhauls. With their knowledge, they also bring to you top-quality products that you can rely on for your racer or street car.

Pelican quality rating for: Supertec Performance (BEST)

[Flieger]

I think you would be fine using the ones you have. They are good enough for Porsche and you will not have to pay the high price for them since you already have them.

[Henry Schmidt]

Originally Posted by Flieger

........edit...... "good enough for Porsche" .....edit.......

Good enough for Porsche gave us thermal reactors, five bladed fan and the nightmare for Dilavar in the fisrt place. We can't believe that the 924 is perfect just because Porsche thought it was "good enough". Porsche like every other auto company must work within production perameters and that means compromises. With the Supertec stud there is no compromises.

[Flieger]

Yes, but these were for the 993Turbo (a good car, IMHO) and it seems the improved alloy/coating holds up.

And, for the original poster, they are free.

I will admit there are better studs, though.

[Steve@Rennsport]

Originally Posted by Flieger

I will admit there are better studs, though.

Not really,....

Those studs have worked very nicely on 993 RSR & GT-2 (race) engines for many years as well as others.

[motley911]

Thanks for the comments everyone. Prior to posting this question I had done some searching and found quite a few horror stories on dilavar head studs, however it is hard to tell if the failures are related to corrosion or poor / inconsistent manufacturing quality. Obviously the early dilavar studs gave a lot of trouble but has anyone had more recent experience (good or bad) with these later, coated studs?

[WERK I]

Originally Posted by motley911

Thanks for the comments everyone. Prior to posting this question I had done some searching and found quite a few horror stories on dilavar head studs, however it is hard to tell if the failures are related to corrosion or poor / inconsistent manufacturing quality. Obviously the early dilavar studs gave a lot of trouble but has anyone had more recent experience (good or bad) with these later, coated studs?

The 993 studs pictured above are the reformulated dilavar alloy studs. Porsche finally got these "right". Highly recommend them. I have had them in my engine for 4yrs/10K miles now with no problems. My engine output is no where close to what you would call a "monster" engine (430bhp). Keep in mind that this is the only Porsche high performance head stud that comes closest to matching the thermal expansion/contraction rates of the cylinder/head material. Meaning more uniform clamping rates across the engine operating temperature range.

[Flieger]

IMHO,

I would love to have those 993 Dilavar studs in my engine.

This is the last time I get between Henry and Steve about headstuds.

[Henry Schmidt]

Originally Posted by WERK-I

......edit......Keep in mind that this is the only Porsche high performance head stud that comes closest to matching the thermal expansion/contraction rates of the cylinder/head material. Meaning more uniform clamping rates across the engine operating temperature range.

As far as I know, you are making a claim that lacks any published evidence I have been unable to find any evidence that Dilavar is used as a stud material in any high performance application. That does not mean it does not exist. Please post any and all metallurgical evidence of this claim. Sounds cool but where the proof? You are not stating an opinion, you are making a statement of fact.

[WERK I]

Originally Posted by Henry Schmidt

As far as I know, you are making a claim that lacks any published evidence I have been unable to find any evidence that Dilavar is used as a stud material in any high performance application. That does not mean it does not exist. Please post any and all metallurgical evidence of this claim. Sounds cool but where the proof? You are not stating an opinion, you are making a statement of fact.

Since when is the 993 Twin Turbo (not too mention 993RSR and GT-2) not a high performance engine(s)?! Heaven forbid anyone ever disagree with the Great Henry Schmidt or offer alternatives to the SuperTec studs.
I suppose the infomercial you posted claiming "The only head stud designed with modern engineering practices." is based upon exhaustive worldwide scientific research?

[Henry Schmidt]

Originally Posted by WERK-I

Since when is the 993 Twin Turbo (not too mention 993RSR and GT-2) not a high performance engine(s)?! Heaven forbid anyone ever disagree with the Great Henry Schmidt or offer alternatives to the SuperTec studs.
I suppose the infomercial you posted claiming "The only head stud designed with modern engineering practices." is based upon exhaustive worldwide scientific research?

Of course I should have said "any other high performance application".

Let's not get your panties in a bunch. There is no need to get personal. Simply stating you have no evidence to back up your statement might be a little more appropriate. To answer your question, we hired an engineering company that specializes in fasteners to design a stud based on current mechanical principles and they found the Porsche stud design to be arcane and ridiculous in concept. Of course this was just one engineering company. To date we have seen no down side to the Supertec stud design. I gave up on Dilavar because we saw issues. Now Dave, doesn't your childish tirade leave you feeling kind of silly?

[motley911]

Thanks for all of the comments guys. The replies are typical of my prior thread searching - some supporting others not wanting to repeat history with divalar.

From my perspective I figured that the cost of aftermarket studs is relatively inexpensive considering the cost of an engine tear-down if the divalar studs fail. In this application I intend to put these under some increased stress (compared to standard) therefore I wanted to see what other experiences were out there. As I indicated earlier - my main concern is with the historically reported inconsistent material properties of divalar, leading to failures.

I didn't intent to cause any bad feelings between you guys and appreciate all of the debate on this topic.

[WERK I]

Henry, when you submit your replies using terms as "get your panties in a bunch", "childish tirade", you exemplify the futility with anyone offering an opinion contrary to yours. You are demeaning by nature, and worse yet, don't realize it.

Motley911, don't worry about the "bad feelings". A lot of us have felt the Wrath of Khan before.

Outta' here.

[Eagledriver]

Originally Posted by Henry Schmidt

To answer your question, we hired an engineering company that specializes in fasteners to design a stud based on current mechanical principles and they found the Porsche stud design to be arcane and ridiculous in concept.

So this company has re-invented the wedge? I understand that they use a different pitch on the threads but other than that they don't seem to be anything other than another (high quality) steel stud. As it turns out steel studs are good for the most part but they can't match the thermal expansion rates of Dilivar and aluminum. If it comes to a choice between a broken Dilivar stud and an intact steel stud I'll take the steel. If I want the one that is least likely to cause a pulled thread on a Mag case I'll use a 993 Dilivar stud. If I am wrong and the Supertec studs are a material that expands at a similar rate to Dilivar then you have my apologies (and my future stud business).

-Andy

[Steve@Rennsport]

Originally Posted by Flieger

This is the last time I get between Henry and Steve about headstuds.

LOL,.......No harm, no foul.

I have "no dog in this hunt" and I'm not selling studs to anyone besides our engine customers, of course. We simply use & recommend what we think to be the best components for a specific application, based on our experiences over the past 33+ years.

To be fair, we've not used the Supertech head studs as of yet simply due to our successes with the late 993TT studs (same as RSR/GT-2). There is no question that these Dilavars cannot be compared to the early Dilavars which were prone to corrosion and soon after, failures. Since we cannot afford a problem with a customer's engine, we tend to use solutions that we know from experience will be durable and reliable over the long term. R&D and new product evaluations are normally done on our own personal equipment or when a customer consents to being the "guinea pig" in such rare circumstances.

We've had similair problems using ARP head studs due to their inability to remain torqued under high heat and rates of expansion. Having discovered far too many loose head nuts using these, we stick to either steel ones for the early small motors and the late Dilavars for the larger bore and turbo engines.

Now,..................some thoughts about these subjects,............

I think its worth noting that rarely are such issues totally black & white. Ultimately, we are all the sum of our personal experiences and our thoughts and statements simply reflect our opinions about various things. Keeping this in mind helps maintain context (and hopefully civility) on such occasions such as postings in such forums.

JMHO, so YMMV,

[Henry Schmidt]

Originally Posted by WERK-I

Henry, when you submit your replies using terms as "get your panties in a bunch", "childish tirade", you exemplify the futility with anyone offering an opinion contrary to yours. You are demeaning by nature, and worse yet, don't realize it.

Motley911, don't worry about the "bad feelings". A lot of us have felt the Wrath of Khan before.

Outta' here.

I simply asked you to back up your claims and you started the personal attacks. Isn't it interesting that questioning your unsupported conclusions qualifies as "demeaning by nature"?


Direct in the "Politically Correct" world is a crime now?

[jacksd3]

I love the head stud war threads. They are the best 2nd only to the Loctite or not to Loctite rod nuts.

[gestalt1]

i also love the head stud wars. to think something so expensive and the even the "best" ones won't add any HP. i think it is important to remember that we really just need them to work. you can't even see them!