Even for a new case, should case savers be installed?
 

Should case savers be installed in a brand new mg case? I will be getting a set of 930 dilavar studs (930.101.170.02), and Nikasil p+c’s.

Look forward to your inputs!

Both Wayne and Bruce Anderson recommend against the Dilavar solution for head studs. Is there a reason that you are planning to use them instead of Raceware?
Wayne's book strongly recommends using the Case-savers in the magnesium case.

Use regular steel before you use Dilavar. There are lots of head stud options out there, dilivar should not be one of them.

Jeff

Oh my god! Pandoras' box has been opened again!

I guess it's to late to call Porsche and tell them not to use Dilivar in all the air cooled motors they built up through the end of production in 97'.

I myself wouldn't build a mag case motor, that uses alloy cylinders, with the regular steel studs but that's just me. I'd go with 993 studs (Dilivar). I think the raceware studs are great but really pricey. I believe they are an alloy similar to dilivar as well but have the nitrogen baked out of them to prevent cracks from nitrogen imbrittlement.

Tough call on the casesavers. They can't hurt and if you should sell down the road they should pay for themselves in the resale value of the motor.

Sorry, I should have said the Dilivar studs used up to 89 are probably not a good choice. The 993 ones are a different story, I would not hesitate to use them.

Jeff

The 993 studs are mostly steel I thought, indicated as a good option by Porsche Motorsports.

I have been using them in the race motors for a while, work great!

My theory too.
http://forums.pelicanparts.com/uploa...1073253422.jpg
Secondly, I think it's better to have a broken stud than a pulled stud.






I thought 993 dilavars were fully threaded whereas 930's are smooth shank? http://forums.pelicanparts.com/911-engine-rebuilding-forum/137251-dilvar-dilivar-whatever-its-called.html?highlight=dilavar

I am confused by the chart. you show a larger coef of expansion and yet a lower change in length for the cylinders than the studs.

The 993 studs generally do not have the problems that the early ones had.

As for your question on case savers, if it was my case, I would do it. It also depends upon the engine too. A 2.0L 911T engine almost never pulled studs because it wasn't exposed to extreme thermal stresses like the California 2.7 engines. If you're building a performance motor then definitely install the case savers. If you're building a T motor, then you can probably get away without it.

-Wayne

Jack

Not ofter

Jack

Not often you miss the obvious :-) , The studs are significantly longer than the cylinders, Also I'm not sure how relevant this is because I doubt the studs operate at the same temp as the cylinders

Neven

Yeh, I see, big difference in length. Won't ask why the big difference, but the stud sticks thru the head, the head expansion also matters in the overall equation. As to temp differance, it is measureable and probably relatively small at operating temp, but durning warm up could be extreem. In any case steel seems to be the best pick, followed by Covar or is it Kovar?

Anyway in the real world nothings perfact, but you do the best you can.

A friend just blew up a New Cosworth engine, seems they didn't warm it up completely and the hour glass shaped cylinders might have worked against them because of it. They figured the lack of warm up was the problem because they are running it DEtuned at 980 Hp.

Jack

I can't see why? There is no direct contact between the cylinders and studs (Porsche explicitly state the studs should not contact the cylinders), As the studs are heated radiantly by the cylinders and by contact at one end and they sit in airflow I'd expect them to be cooler, maybe someone could confirm this.

Neven

True. As Jack said nothings perfect, you do the best you can. I remembering seeing a picture of some studs that had fiberglass jackets to counteract the cooling effect of the air over the studs. Kind of a "pig in a blanket" if you will.

Use full threaded 993 studs.,cheers Antonio.