993 Head Studs

[dcriss]

After asking and asking and asking everyone from local PCA members to local track road racers, I was repeatedly told to go to a local European Repair shop and ask for Phil, the shop's Porsche expert. So went there and asked for Phil. I told Phil that I was in the middle of a complete rebuild of my 1980 3.0L SC and I had several questions. Phil put down his tools and talked with me for about 45min. He answered ALL my questions and then gave me a long list of tip and tricks and even showed me examples on an engine he was working on (a great guy and endless base of knowledge).

Anyway, one of the things that he suggested and he had even put in his own 2.7L rebuild were, “Full Thread, Non-Magnetic, 993 Head Studs”. He said that he had used them on many engines (even race engines) and had yet to see a failure. He liked the expansion rate of these studs, especially with the Cold to Hot to Cold changes that we can see in late October/ early November, here in Michigan. He stressed, DO NOT use the Dilavar studs that were on the original exhaust side of my 3.0L (I had already planned not to).

Anyway, I went to the Pelican Part On-line Catalog and looked for these (suggested) studs. Guess what? The webpage (http://www.pelicanparts.com/catalog/shopcart/911L/POR_911L_ENGpis_pg7.htm#item31)
says this “Cylinder Head Stud, Mounted into case, (24 required, sold per each), 993 - fully threaded, DILAVAR, 911/911 Turbo (1965-98)” ……DILAVAR????? .....and at $$38.25 each ($918 for 24 set)
….he told me that these were less expensive than Raceware….?

Another question is that if Porsche knew that Dilavar studs had issues, why would the 993’s have them? Were the , “Full Thread, Non-Magnetic, Head Studs” used in production on the 993’s?

I am going to go back and ask Phil to clarify. However, are there different “Full Thread, Non-Magnetic, 993 Head Studs” than the ones on the Pelican page?



If anyone has info, please post.



Broken (original) 1980 3.0L Stud

Thanks,

[1972_911T]

No they are the ones hes means, by non magnetic he is implying the diliver studs which are priced as above.

Be aware you 3.0 SC would only use 12 diliver studs on the bottom row the top 12 would be steel.

Steve

[dcriss]

Are the Dilavar 993's different from the Dilavar's on my original 1980 911sc.

Anyway, I am replacing ALL 24 studs, NO MATTER WHAT!\\ ......What is a possible +200,000 mile rebuild worth?

Thanks,

[Dennis Kalma]

At the expense of starting a war, there appears to be two minds regarding studs. One is to use steel studs, with varying choices including Raceware and Henry Schmidt's studs. Second is to use 993 Twin Turbo studs, which apparently are a better dilavar material.

I get confused personally, both sids of the argument appear to be valid in that there are very few stud failures with either of the two approaches. The more modern steel studs have lots of great experiences out there, but then again, the 993's did not have any stud breakage issues that I have heard of so they are obviously successful as well. I can see the value of steel (nice and strong), but then again, they are compressing what essentially is an aluminium column, so the dilavar's expansion rate, which is similar to aluminium, should maintain a more consistent clamping pressure.

I guess it comes down to price and preference?

All I know is that I have to buy a set for my 3.4 project car and I get slightly confused...

Dennis

[911 tweaks]

use the supertec head studs. Call Henry to discuss. He is frequently on this board. He is in Fallbrook, CA. Google it to call if you want. That is my best suggestion and is also many here on the board.
Have any engine pics?? We love them...
Good luck!
Bob

[cnavarro]

There are lots of choices - Supertec's studs, ARPs, Racewares, Performance Developments (Neil Harvey), and a few others that I've seen online but never in person. I have had alot of customers use the ARPs and if those were not available, I usually source Neil's, albeit more expensive.

[Dennis Kalma]

Anyone use the Porsche 993 twin turbo studs?

[dcriss]

WOW! I got long winded and Dennis hit it right on the head. “Anyone use the Porsche 993 twin turbo studs?”

Furthermore, I need to THANK, ‘1972_911T (Steve)”… he is right…only 12 Dilavar on the exhaust side and 12 Steel on the intake side. Umm, I would think? …993’s are Dilavar and Steel. Right? Thanks Steve.

Anyway, I was once told “Brains Are Cheap” So, thanks to all of you for your posts (Brains) and keep it coming.

[1972_911T]

And if the choice wasn't hard enough now theres Casper labs high performance dilivar stud with life time guarantee

Decisions Decisions Decisions

Steve

[ChrisBennet]

For a 3.0 I'd just replace the lowers with steel 993 studs (not the dilivar ones). But I'm cheap. The steel 993 studs are the least expensive Porsche head stud.
-Chris

[cgarr]

Originally Posted by ChrisBennet

For a 3.0 I'd just replace the lowers with steel 993 studs (not the dilivar ones). But I'm cheap. The steel 993 studs are the least expensive Porsche head stud.
-Chris

I did the same as Chris, Just the lowers with 993's

[J P Stein]

I used the full thread coated Dilivar studs in all 24 spots 7 years ago on my
2.7L.
All the nuts were still tight from the original torque. Can't ask for much better than that, I figure.

[Steve@Rennsport]

Originally Posted by Dennis Kalma

Anyone use the Porsche 993 twin turbo studs?

Thats ALL we use on 2.7's and larger, engines.

No ARP or Raceware studs for me, anymore.

[1972_911T]

Originally Posted by Steve@Rennsport

Thats ALL we use on 2.7's and larger, engines.

No ARP or Raceware studs for me, anymore.

Is there a reason for this? have you had bad effects from performance studs? A full set of the 993 ones works out $$$ compared to supertec et al.
Steve

[Steve@Rennsport]

Oh yes,...

We've had issues ranging from loose head nuts to loss of head sealing between the top and bottom row of studs from excessive clamping when very hot.

Porsche REALLY put a lot of engineering into the Dilavars and the late 993TT ones are bulletproof. Head torque and clamping stays uniform from cold to hot (even on Turbo motors that can see 450 deg head temps).

[Tim K]

Originally Posted by Dennis Kalma

Anyone use the Porsche 993 twin turbo studs?

Dennis,

I was at Hima Haher's shop in Calgary a few years ago. He was more than happy to show me the work they were performing on his 911 Turbo race car. He suggested the 993 (turbo?) studs as well. He's a wealth of knowledge and I wouldn't hesitate to stop buy and pick his brain re: any other engine rebuild questions.

http://www.riegeltuning.com/index.cfm

Tim K

[dcriss]

Originally Posted by J P Stein

I used the full thread coated Dilivar studs in all 24 spots 7 years ago on my
2.7L.
All the nuts were still tight from the original torque. Can't ask for much better than that, I figure.

Good info.

Dilavar in all 24 spots...and 7 years to boot . Steve Weiner seems to agree. It sounds like a bit of a hit in the pocketbook, but broken studs were the reason I start this project.

Even though I am enjoying the rebuild, I would rather be driving. So if I can get 7 years of driving and not rebuilds, than that sounds good to me.

[cnavarro]

Steve, would you still use dilivar studs on a cylinder where the heads studs are not encapsulated and exposed?

[Steve@Rennsport]

Originally Posted by cnavarro

Steve, would you still use dilivar studs on a cylinder where the heads studs are not encapsulated and exposed?

I sure would, especially with alloy cylinders,..

[J P Stein]

Originally Posted by cnavarro

Steve, would you still use dilivar studs on a cylinder where the heads studs are not encapsulated and exposed?

I assume you're talking about a T-4 application here.
I'd be interested in Steve's answer to this also.