I am working with ARP on making head studs for the 968/944S2/928. These studs will be much stronger than others and will work with the Al block and heads.
I need the length of a 968/944S2 head stud as well as the depth from the block deck to the bottom of the hole AND the depth from the deck to were the threads start.
I do appreciate the info and when we get the studs ready to be made I will let everyone know when they will be ready.

Thanks,
G

 

I would have thought ARP could buy a factory stud to use as a pattern. There are at least four different stud specs among the various S2, 968, and 928 motors.

 

Not sure if you already knew this, and are looking for an alternative, but Raceware already makes head stud kits for all the 944/968 variants.

 

I understand that there are differnt lengths. I need the specs for the 968 and 944S2 motors.
We do not want to just copy a stock stud, hence the reason for needing to know the specs from the deck to bottom of the hole and when the threads start.
I hear that the Raceware studs tend to break under extreme loads and sometimes many torque cycles.
We plan to use the new ARP 2000 material which is well suited for the AL block and head growth, plus the threads will be rolled as are the stock studs.
As for 928 motors, the '89 and later heads are the same thickness as the 968/944S2 heads and I believe the 968/944S2 block stud holes are the same as the later 928 motors, but I need varification from someone who has a 968 or 944S2 block. Also, there are no head studs available for the '89 and later 928 motors.
If everything is the same as I suspect, then ARP can reasonably justify making studs for these Porsche motors.
ARP is a highly recognized and proven manufacturer of engine fasteners. Wouldn't we all like having a choice of head studs that can take the pressure?
If anyone has a block, I would greatly appreciate the needed information.
G

 

ARP kits are being sold by EBS racing as we speak. I have one in my possesion as a matter of fact. They look like the standard studs just in their black ultra high strength steel.

 

Who have you heard from regarding Raceware fasteners breaking. In 10 years of selling them we've never had one failure. I'll be happy to contact Randy Hubbard, owner of Raceware to find out if there has ever been a failure if you'd like. Not to discount the quality of ARP or any other competitor but I think the statement Raceware fasteners fail or break in this application is false.

 

Yes, EBS has made a special order for those head studs. But I think this is only a small order. ARP has made those studs but until now, did not know what they went to. If someone gives ARP specs as says make me some, they do. ARP will not know what they are for.
Thanks for letting me know that EBS has ARP studs.
AS for RAceware, I am not trying to debunk them, I am simply stating from two sources that they have broken in the past under high pressures. One must remember that in any apllication that if studs are not used correctly they can break. This may be the cause of the stories I have heard. But, at 25-40psi things happen.

 

It would be nice to know the sources so we can determine what the cause of failure was. 2 reported failures over thousands of sets of studs would lead you to believe it may be something other than the products fault. Sounds as if you will be bringing these new studs to market...is that the case or are you an end user?

 

I believe I have read Bruce Anderson making reference to broken Raceware stud for 911 motors, but have never heard a thing about 951 Raceware studs breaking. The 911 head studs are wildly different obviously.

 

Wildguy, what is your affiliation with ARP? I find it odd that ARP would need someone to post to a bulliten board to get measurements. You have heard of two failures where Raceware studs were used in 944S2 or 928 or 968 blocks, converted to turbo, running 25 to 40 psi? How many such cars are even out there? Who runs that kind of boost? How did they fail? If you are referrning to 911 applications, keep in mind that those studs are asked to perform an entirely different function. Even in 911 motors, Raceware is the stud of choice over ARP. My apologies if I sound skeptical, but...