I disagree with the economics. Porsche had a solution to the broken dilavars by switching to steel. They then switched back to dilavar. The dilavar studs cost more than steel.

The costs are not in the manufacturing as much as in the warranty costs and brand damage. In essence, spend a little up front to avoid unhappy customers during the warranty period.
Engineers design with criteria that is sometimes obscured from the consumer. Mass production comprises we'll call them.
The plan behind using Dilavar in a production motor was an attempt to control seepage from the heads on cool down. It had very little to do with seating pressures at operating temperature.
The engines of the time were designed with thermal reactors and they created a serious dimension problem after the engines were shut off. These 1800 degree cans located directly below aluminum cylinders were rediculous. Ever wonder why the SC only had lower Dilavar studs?
The issue was studs pulling from stresses after shut down. I was working at the dealer during this nightmare and we were repairing engines left and right under factory warranty. Most were for oil leaks and head seepage. Not to mention tensioner collapse.
This high temp cool down (the engines actually got hotter when first shut down) was a real warranty issue.
Dilavar was installed to deal with high heat from smog equipment not as a performance enhancing revelation.
The turbos exhibited the biggest problems so in an attempt to deal with this issue Porsche, in it's ultimate wisdom started to whack fins off the turbo cylinders. This was an attempt to control expansion issues at cool down even though the engines were equipt with Dilavar. We in the private sector figured out the problem. Too much heat. Porsche was stuck with thermal reactors and we were not.
How many of you are willing to whack cooling fins off your cylinders so that your engine won't seep on cool down.
I for one was not. We controlled the temperature by removing smog equiptment, improving coolers and registering the cars out of state. Porsche stuck with the half finned cylinders as a compromise in order to sell a smog legal car. Don't believe for a moment that half finned cylinders was not a compromise. They comtinued this compromise far beyon the thermal reactor was removed. One of the cool things about building custom engine for specific users is that we get to eliminate some of the production compromises that mass production demands.
When Porsche discovered the breaking issues with Dilavar they painted them. Throughout this breaking stud period Porsche tried different sealing techniques to little or no avail. They tried to remedy the issue with a ce ring, no gasket, an asbestos gasket and then a sealing ring and then replaced the studs with steel only to find that the old design steel stud was perpetuating a warranty issue again. . Knowing that the air cooled engine was coming to the end, Porsche went back to what they remembered. This time they addressed the breaking issue by adding material. Still a compromise but that's what production lines must do to survive.

BTW: This is from memory. I lived it, I didn't read about it in a book.

So on a Carrera or SC (neither of which had thermal reactors AFAIK) using all steel studs will result in head seepage?
I'm especially interested because I'm about to rebuild my SC engine due to a busted head stud.

Using stock steel head studs on an SC engine will generally result in seepage.
Heat will be an issue as will your right foot. The harder you drive it the more likely it will seepage.

We just took this 2.7 MFI engine apart on Tuesday. Car was driven hard.
All head nuts were torqued properly.
Note the seepage.
No CaseSavers were pulling.
Note the head movement.
Note the stud we removed.
This engine had 17,000 miles on an OK rebuild.


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I don't know enough to judge from those pictures so I'll take your word for it. According to Wayne's rebuild book steel is fine for a non-race engine, glad I asked. Thanks.

Steel studs work ok on my 3.0 race motor and were free (used ones from my machinist). They did need to be retorqued after a couple of races because some of them became loose. They have stayed tight now for 2 seasons, but I check them every year when I check the valves. They don't work as well as the two expensive options discussed here but I'd rather save the money.

-Andy

Great explanation Henry!

I for one am please that people like Henry, Chuck Moreland and Steve Wong, not to mention Wevo, Rennshift, Seine Systems, etc, etc are developing new and improved products for our cars. Without this innovation, we'd all have a less fun environment to play in.

Henry, do you think that the pictures of the 2.7 you showed us above would have been different if the car was for street and not driven as hard? (Or was that a badly beaten street car??).

88 Diamond Blue and ixOifan,

I spoke to Neil @ Performance Developments and asked him many of the questions raised here. Got some really interesting information. I will PM his answers to you both offline. Not trying to stop the flow of information and resources, but I too believe its time to go.

Many had PM'ed or emailed me for a copy of Neil's (PD) opinion of Head studs. I replied to all I think, but in case I have overlooked someone, please PM me or email your address and I will forward.

Sorry for the delay. He had sent me something sometime ago, but then sent a more in depth opinion today.

Simon

Why not just post it here?

Lindy

Have you ever heard of the term; "Perfect Storm"? ;)

If I forgot someone who had requested the document, please email me again. I sent out approx 100 and may have missed someone by accident.

Simon

I'll be using these!! :D:D:D
Thanks Henry!


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Im jealous! I really need to buy a set!

My friend mechanic was impressed by them.
He also had the impression they were light compared to OEM studs. (which in my book is a good thing, adding lightness!)

Am resurrecting this ol' thread to put Henry on the spot since... he seems to be the only stud-man that's put his money where his mouth is. If I'm wrong about this, apologies in advance. Also, I read through a good bit of the thread but not the whole so might be more to piss on me for but here goes.

Supertec offers a lifetime guarantee. Bold move for sure. But then disclaimers can easily lube a guarantee to the point where it's so slippery there's no holding on to it when push comes to shove. In the case of Supertec, I know the guarantee mentions an inspection of the engine which makes perfect sense...

Henry... if you're still around, would you speak more about the guarantee. The purpose being to squelch any notion of the marketing department running the show as opposed to Supertec's studs actually being a superb product capable of standing up to the lifetime guarantee.

I can pretty much state the "marketing dept" doesn't run the show at Supertec. Consider me one satisfied customer. Although I don't have the car/engine any more.

+1...been in an engine for 8+ yrs w/o any issue...
maybe is someone having a slow day at the office & needs to micro the micro of he micro of the micro, ~ infnity...???...)))