I went with ARP in my 3.4L turbo rebuild. However, it was Neil Harvey of Performance Developments that did all of the machine work on my engine. I had already purchased the ARP studs before I knew Neil existed. Neil has some "engineer friends" at ARP and he basically echoed the same thing that Ralph mentioned: any of these aftermarket studs are superior to what the factory used - just take care with installation. Neil had NOTHING negative to say regarding ARP and their products. In fact he joked about how nice the ARP packaging is! However, if I had it to do over, I would have bought Neil's studs...just because of the amazing job he did on my parts and the guidance he offered regarding me doing the final assembly. I did use Performance Developments exhaust studs. Anyway here's a link to Neil's studs:
http://www.performancedevelopments.com/products_engine_studs.php

I'll also mention that the boys at Imagine Auto (where I purchased my ARP head studs and rod bolts) typically use ARP in their engine builds...Stephen Kaspar is no stranger to the turbo engine!;)

I appreciate all the comments offered here.
I understand that ARP is the band name people know and my studs aren't really marketed to the general public so very few people know about them.
I am wondering why no one has chosen to comment on the true difference between Supertec head studs and all other studs on the market.

I manufactured my stud not to be in the stud market, but because I wanted a superior stud design and no one else manufactured it.

Of course I have a very limited exposure to other types of high performance components but in my travels I have never seen a high performance engine or trans that used coarse thread nuts on a stud that required a specific torque.

Cosworth, N.P.T., Hewland, Ferrari, TRD, Rolls Royce, Continental and Lycoming aircraft engines all used dual thread studs in aluminum castings. I would be willing to wager that not one F1 engine or trans uses a coarse thread nut on anything other than wheels.

Recognizing this fact led me to design the Supertec stud. It seems that the consensus here is, that it doesn't matter. My question is " why not ?"

Henry,

It sounds like you are beginning to get discouraged...:(

I think that you fall into the same boat as Neil with respect to marketing your studs. You both have to go up against the "big guy" like ARP who seem to have fasteners for every type of engine available and have a large marketing budget while you guys both specialize in a narrow, niche market. ARP seems to rely on their name and reputation in other markets and simply hopes that it transfers to the air-cooled 911 market as well.

My only advice is this: if you make a good, reliable product the word will spread (albeit sometimes slowly). Having them for sale with mailorder companies certainly doesn't hurt nor does the free advertising that you provide on this board...patience Henry, it will come, although you won't catch every fish out there...:)

If I had the engineering background to comment on the differences between your head studs and the others I would, but quite frankly I get lost with all of the technojibberish bandied about...:) I've just used ARP's over the years on other engine applications and never had a problem which is why I used them on my own motor and a few others. Supertec or one of the other guys may very well be much higher quality, but I simply use what I am comfortable with. If one were to break and it was a stud issue and not me screwing up the installation, I would look for an alternative...

My original post was simply to question what the warranty on your studs meant, not to pose a referedum to credit/discredit the quality of your studs or anyone else's...

You may well be on to something with your studs that others simply don't care about or deem to be important, I really don't know. It may very well matter. What you say regarding coarse vs. fine thread certainly seems to make sense...:)

Like many topics, you ask 100 different people the same question and you'll get 100 different answers... :)

Ralph

EDIT: I had my smilies and sad faces in the wrong places...:(

Thanks for all of your advice I appreciate it...

I am so pleased that I asked the question in the first place as I am sure that I will buy an aftermarket set of studs as it is clear that standard steel studs will not hold the heads down properly. This has certainly been the case with the studs that are currently used in my engine.

My logic is to buy something that will hold the heads down at stock power and from what I can determine all of the aftermarket studs will do this for me (ARP, Supertec, Performance Developments etc.)

It is now a simple choice of price and availability...

Regards

Steve

Guys, before this thread dies and it sinks into the archives, Neil Harvey emailed me this afternoon and asked me to post his thoughts on head studs & his opinion as to how they should be installed. Apparently many of you have called and emailed him with questions and he thought it may be better to simply have his opinions put in print for all to read. Please note that this is his opinion, I am simply retyping his email (and correcting some spelling errors)...Please note that it is LOOOOONG:)


"I thought it to be good timing to offer up my opinion on this whole debate about which head stud is better, etc. First off, this is my opinion, which is based on my engineering knowledge and many years of experience. Some of that experience is from success and some is from failures.

Which head stud is better? I offer no opinion here, other than most aftermarket studs are all well above the required specification required. This includes all racing applications. It is my opinion that the most important point is the installation and the correct use and care of these fasteners.

Some may find it necessary to "put down" other brands in an effort to elevate their own. I find this somewhat distasteful, especially when there are no installation guidelines or "do's and don'ts" provided. I also have read what is supplied as differences, and if what is quoted on the Pelican website, somewhat contradictory.

Let's look at the differences first. Most of these studs are all made to the same dimensions. Some have fine threads at the nut end, and some have metric coarse threads. The factory stock studs have coarse metric threads at the nut end, and we at Performance Developments looked at this and decided in our design to follow suit. We chose this route for ease of application over the "best fit" fine thread offers. Knowing how these studs are typically installed (the errors often include proper torquing), we went for the ability to use the factory nut. Absolutely, fine threads offer better torque control than a coarse thread, but all things being equal in the typical installation, this benefit is often lost. This brings up one of the mystery's that puzzles me. In the Pelican sales pitch, one of the competitor kits is offered with serrated flanged nuts. If I'm reading this correctly and the information is true, why would you use a serrated nut in an application where torque control is required, and where you went to the the trouble of using fine thread to gain this advantage?

From reading some of the emails sent to me regarding what has been talked about, it appears that some competitor studs are made from the same material as ours. There are only so many high grade stainless materials available for this type of application. It would not surprise me that more use the same. But from reading the various manufacturer's specs posted, it appears that there are some major differences. I read that "Brand X" spec's out a heat treat specification of HCR 38-42. This is achieved by the heat treating at 1025 degrees for 4 hours. This is on the low side for these types of fasteners today. Performance Developments (and most others) specify a higher spec, H900 which produces an RC level of 44+ averages. The lower RC of 38-42 shows in the accepted SAE specs a tensile strength of 150,000 psi. The higher H900 provides a more typically accepted value of 200,000 psi tensile strength.

All of the above is good detail work when you wish to manufacture a high grade stud. Why not make it the best it can be? But all of this is somewhat of a waste of time and a waste of a good fastener if the installation is poor.

So, what are the correct ways to install these studs? There is no one correct way. I am sure there are many. I will offer up the way we install and recommend.

First, proper care should be given to these studs when handling them. Do not treat them like any other stud or bolt. No nicks or scratches are allowed. Always do a dry assembly first, to make sure the installed height is correct. Make sure all gasket thickness' are allowed for, and while the mock-up is assembled, it's always a good idea to check that the spark plugs and socket will fit if a twin-spark application is in use. After the mock-up is done and all the installed heights are set, be sure you have a known torque value you will use and that this value has been used before without any collateral issues. What may these be? One in particular comes to mind. Often when the engine may see very high boost or very high static compression ratios are built in, some find it necessary to increase torque values. This may be required, but always check that the cylinder head will tolerate this extra clamping force with collapsing, the stud indeed stretches more without pulling out of the engine case, and most importantly, the main line bore of the case does not distort. This last point is often the case, and always unknown as usually the bottom end is together when the heads are torqued. The way to check this is to build the mock-up without a crankshaft installed and to measure the main line bore after the stud is torqued. We do this every time when increasing or changing the torque values. If we check the head hardness and find them to be "soft" the torque values often change.

Once the set-up is all complete, the studs should be installed without loctite, but with a good grade of anti-friction grease. ARP supplies some of the best grease for this application. If loctite is used, then you have to be sure to torque the head nuts before the loctite has cured, or the torque values will change. We want the stud to turn if it needs to, as this ensures no friction is added to or subtracted from the required torque value. We have a setup head or heads: in fact it's a block of machined aluminum that simulates the head in place. We install the studs, fit this fixture and do our torquing. This requires us to pre-measure the stud length and then re-measure after stretching. We establish the same amount of stretch on each bolt and record the amount of stretch, angle and torque value. This is all done with the aid of a computer based torque wrench. Once the mock-up is disassembled, we go back and check that the studs have returned to their original unstretched lengths.

Other points to watch out for are the cylinder head and the washers. All heads are remachined in the counter bore where the head washer sits. This ensures that the surface is flat and has not collapsed from the head being soft from heat cycling. These heads do go soft and do collapse around the head stud. Make sure the head washer is flat on both sides. Some factory washers are beveled and the nut will than contact in one very small part. We often counter bore the heads so that we can fit a stepped washer and this step holds the head from collapsing inward around the head stud. Always check to see what the hardness of the head is. Soft heads will never net you consistent head torquing numbers.

This is maybe why some engines have had issues with nuts coming loose. I think that the factory studs stretch a little more than the aftermarkets do, so this may be the reason why the factory studs have not given any problems. This extra stretch may take up the difference and allow the torque or tensile to go into the stud and not collapse the head.

It's all about basic installation techniques and using "your" head. Is one aftermarket stud better than another in these applicaitons? I think not. It is far more important to install them properly and do all of the pre-build work. I really think all of this hype generated is simply marketing and sales"

Neil Harvey
Performance Developments



Man, my fingers hurt from typing 2 1/2 pages! If you have questions for him, please email him at neil@performancedevelopments.com or call him at 949.646.7461. I'm not going to be the typing "middle man" again!:)

:D

I like Henry, and I like his head studs period! Being an artist I would consider them a real work of art.... keep up the good work Henry, some of us appreciate your hard work and diligence to bring about the very best products that can be produced for our cars. The quality shows.

Neil, thanks for all the information and wisdom you've shared with us about your conclusions concerning head studs.

vote for Supertec
 

I went with the Supertec studs for my rebuild and found them to be an excellent product. They arrived not only with studs, nuts and washers, but great instructions, a tube of blue threadlock, and moly lube as well! The installation went smoothly via double nut intstall process (2 fine thread thread nuts were also included for this) and they sure looked beefier than the standard studs that were one my bench about to go in.

I can't comment about Supertec vs ARP or whatever else is out there, but Henrys enthusiasm for the early engines and his continue sharing of his expertise here is just icing on the cake - kind of why I order parts from Pelican as well.

Regards,
Andrew M

I agree, it is distasteful. I wonder if the term "Brand X" would be considered a "put down"?

Just wondering.

I'm certain I didn't put down anyone's product, certainly not Neil's. I had no idea he makes a stud.

BTW: When designing our stud (7 different versions during testing) we considered many different factors and the material for our studs was chosen for it's expansion rate not just tensile strength. 150,000 psi in this application seemed more that adequate. See test results below for actual tensile strength.

As for stud installation, we install the studs by bottoming them and backing them out 1/4 turn. This allows for the most threads in the case possible. Loctite is used to insure proper location. Supertec studs by design are not susceptible to incorrect installation height so there is no need for fancy fixtures or time wasted measuring the length. Nuts are installed with anti-seize as per instructions.

12 point serrated, flanged nut are used on 928, 944 and 968 connecting rods. Certainly in that application they torque accurately and have not been noted for loosening during use and to date have not loosened in our application.

Quality control is as important if not more important than the ability to spew opinions. Read bloviate. To bloviate (pronounced BLOW-vee-ayt) is to speak or write over expansively or with undue grandiosity. It suggests a derivation from to blow , meaning to boast .

Anyone else care to post their test results?
Note specification: Fry Steel 174-T2a cap of H900, H950 (05/07/03)

http://forums.pelicanparts.com/uploa...1154234861.jpg http://forums.pelicanparts.com/uploa...1154234874.jpg

I think it is only natural for Henry to be proud of his studs and their uparalled record of never failing. If he wasn't...I would find that suspect. I like taking my business to a fellow enthusiast who is fired up about his work. As an engineer working primarily with high performance aircraft and space applications, I selected Supertec studs because of their design and their rigorous testing. I too, wondered why fine threads were not normally used for this application since that is standard in the aerospace industry. IMHO head studs seem to be the weak link in Porsche engine design/repair...so using the right studs was imperative. Henry back up his studs...and all his work...IMHO the best in the industry. He actually warrantied my engine for 2 years (which came and went without incident)! He also contributes to this BBS and dispenses lots of free information that is invaluable...and unobtainable elsewhere. That said, I will continue to support Pelican and professionals who post here with all my 911 business.

Yawn...

What do you mean exactly?

LOL

Unfortunate reality of the fastener business....you only hear about the failures. No grandiose claims of umpteen million HP increase, just "they didn't break".

Do you need to re tighten ARP head studs on a 3.2 ? When to do it ?how best to do it?
John