What Studs For SC
 

Hello all, I have an 83 SC (97K Miles) with at least one broken head stud. I recently suffered the exploding airbox and figure now is the time for studs and clutch as well. I was going to replace only the lower dilavar with steel, however I just spoke with a Porsche service rep who recommends replacing the upper steel studs as they have stretched and the action of relieving the stress on them and re-torquing them will lead them to snap. I haven't heard of the uppers doing this. Has anyone had this problem??

Additionally I just read on this BBS (dreaded dilavar studs) that the steel are not really good enough, that we need better studs (supertech, race ware, ARP?) Our hosts book says steel is good enough. Thoughts??? I'd like to only do this once!!

Thank's in advance.

You dont see steel studs breaking. SC only uses 25ft# torque on the heads. Thats not going to stress any steel.
Bruce

Just my two cents: I have Supertec head studs in all four of my 911 engines from 2.45 carburated to 3.5 Turbo.
They are without a doubt the best stud on the market. For $600 or so bucks it's cheap insurance. I saw a recent post that showed how stock steel head studs allow the heads to move on the cylinders.
There are lots of threads on head studs but I have never read even one negative thing posted by anyone that actually used Supertec head studs.

They are available from our host.

Yep, that post just scared me into going to the high performance studs. Better safe than sorry.

Supertec ONLY for me.

For a street SC I'd use steel and only replace the bottom row. You can buy better studs, but you don't need them. By the way I'm using stock steel studs on my race motor.

-Andy

Has anyone ever reviewed the porsche engineering justification for using dilvar studs. Was it a mistake, or a valid concern? Was it engineering paranoia that resulted in an overkill solution or was porsche just sold a bill of goods by the developer of dilvar. probably no way porsche could have tested the long term problems of exposed dilvar studs but why did they use them at all if steel is ok.

Although it doesn't make a great deal of sense, sometimes it's easier to compromise on a race engine when you are not looking for 100K longevity.

There are a number of threads that speak to the issue of Dilivar and why the factory used this horrible material but in general it had to do with seepage and warranty concerns. The heads were seeping on cool down creating a warranty issue. Porsche engines are moist and that just a fact that can not be cured. There are ways to limit this seepage.

The funny thing about the Porsche designers/engineers is that quite often we see a new batch of baby designers making the same mistakes that earlier designer corrected.