Cylinder Head Stud: Choice, and Why!?

[Henry Schmidt]

Originally Posted by KNIGHTRACE

I was asked for my opinion on studs by a few people recently. The most important thing in studs is the proper expansion rate in relationship to the motor and of course not breaking. I have used stock steel studs, 993 TT and supertech studs with good results.. I have had ARP and RACEWEAR give problems from not enough expansion. That being said it depends on what the motor is used for and what the power level is. If you building a 200 hp to 300 hp street motor even ARP or Racewear will be fine.. It also depends on the case, 993/964 have O rings and no copper base gasket to crush and cause leaks.
I use the 993 TT on my higher HP builds because I have very good results with them.. The supertech stud could be as good or better in that application I just do not have the experience with them north of 400 hp to say for sure. I have used them in 320 3.6 builds and a few 3 liter to 3.2 motors. They look like a good stud, The advantages they have like install after the piston and cylinders are on is probably helpful to a nonprofessional engine builder. I put them in before P&C so little to know difference. I have used the 993 TT on a 3.5 liter turbo motor I ran at 2 bar of boost with no issues.
if your building a mag motor I suspect the supertech stud may be the better choice due to Henry putting in much more time and effort than even Porsche did. If it doesn't expand enough on a magnesium motor you pull the stud from the case not break it. Henry has had 44 years to improve the stud on those motors when Porsche stopped, I have a similar advantage on camshaft design, I have had about 25 years of development and testing since Porsche quit.. These advantages or advancements made by small shops like Mine and Henrys and other shops help the enthusiast today. It give you good choices.
Summary, there is a time and place for everything and you have to factor cost vs benefit.

It would be easy to tear this post apart but I get the feeling William was bullied into posting on this subject. Much like the twin plug, single MDS thread.
Valiant effort but not much heart.

[KNIGHTRACE]

I have plenty of heart, but I am allergic to drama. I personally had rather encourage or help people not tear them down. This is not directed at any one person, I am just trying to explain why I do not wish to engage in these threads where it seems like a drama show to me.

[Henry Schmidt]

Originally Posted by KNIGHTRACE

I have plenty of heart, but I am allergic to drama. I personally had rather encourage or help people not tear them down. This is not directed at any one person, I am just trying to explain why I do not wish to engage in these threads where it seems like a drama show to me.

Allergic to Drama? I used to be allergic to alcohol but damn if I couldn't stay away.

Alas, poor Yorick.... I knew him, Horatio: a fellow
of infinite jest, of most excellent fancy: he hath
borne me on his back a thousand times........

I forget the rest but you get the idea. This is drama.
What we see most often in these threads is hubris mixed with hurt feeling and egos run a muck.

To help, you offer actual data backed by experience sans confirmation bias and personalities.

[dtxscott]

Originally Posted by KNIGHTRACE

I have used stock steel studs, 993 TT and supertech studs with good results..... That being said it depends on what the motor is used for and what the power level is. If you building a 200 hp to 300 hp street motor even ARP or Racewear will be fine..

Head studs and firearms in the same thread? Wow, this one really delivers! It sure warms this Texan's heart.

My inputs are not to add fuel to any argument but to share my findings for others to consider. People in the 1-2 Sigma category of use-cases.

Like any good engineer, the answer to any problem usually starts with "It depends...." I find there are few absolutes in life so I look at the application and situation. I took the approach William notes above. I wanted to be practical as I have a stock 3.2 that sees a few thousand miles a year.

Additionally, I consulted with a trusted Porsche tech (40 years of dealership experience) and his counsel was to go back with steel studs on a stock engine. He's seen Dilivar broken on new car deliveries and seen them go 200k miles. I understand his viewpoint is to build an engine and make sure it doesn't come back for a warranty claim and I just want a reliable mill.

Just like when people ask me what firearm they should buy.... I ask about the intended use. Bigger and badder is not always better given the use-case. One wouldn't use a 50BMG for a house gun nor a .22 short for Antelope hunting at 400 yards. As always, "It depends...."

[KNIGHTRACE]

Scott,
Scott C, I appreciate the support.. There is not one good solution for everything. Everything has some problem 993 TT is price and no one cares for the all thread. Supertech studs almost are never available when I call. I do not have enough experience with them on high hp builds mostly because he is always out of them. Now to more interesting fun stuff while you brought it up.. I have a TRG 42 in 338 Lapua. I shoot it better at 1500 meters than anything I have ever owned including the AI I sold. But the 338 Lapua wouldn't be good for deer but will outrange a 50 BMG all day. I am a 45/70 fan and I prefer single shots. I have S&B, US Optics, Lecia scopes but I find Valdada to be the most clear. Hopefully this was a nice shift in the thread.

[scooterp7]

SAKO makes excellent rifles. ��

[dtxscott]

338 does a nice job on 300# hogs here. I've tipped a few over at 200 yds with 338. One shot and no movement.

My preferred tack driver is GA Precision .308 with a Leupold VX-3 8.5-25 50mm objective. I can consistently hit a pumpkin at 700 yds and a human silhouette at 1k yards with some serious drop compensation.

When I win the lottery, it will be the 408 CheyTac from Cheyenne Tactical. I've wanted one for years.

For a truck gun, the 300 blackout in an 8" SBR (with Tax stamp). Ballistically equivalent to 45ACP with 30 rounds. Good for hogs and varmints of all types.

Now I feel the urge to send some lead downrange! Alas, I need to pay for my 3.2 rebuild. Too many expensive hobbies. UGH!

[KNIGHTRACE]

Scott, did you know the 408 round is the only round that stays stable when it falls subsonic ? True and it makes it the best round but it was actually an accidental discovery on the stability. Rounds too hard to get for my taste. My TRG42 has a 5-25 34 mm US Optics.

[911pcars]

Can we get back to anecdotal opinions? :-)

I decided to use (actually reuse) the 993TT Dilavar studs because they would cost too much to replace in kind (~$40-$60x24) or switch to the alternate studs discussed here. It came with the engine I touched up a bit. How's that for being "helpful"?



Sherwood

By the way, why aren't all bullets shaped to a sharp point? Is that enough minutia to take this off-topic again?

[KNIGHTRACE]

I can answer the bullet question it gives a lower BC. But I have reused 993TT studs several times no issues.

[Henry Schmidt]

Originally Posted by 911pcars

Can we get back to anecdotal opinions? :-)

I decided to use (actually reuse) the 993TT Dilavar studs because they would cost too much to replace in kind (~$40-$60x24) or switch to the alternate studs discussed here. It came with the engine I touched up a bit. How's that for being "helpful"?

Sherwood

I'm guessing by the pictures, that's a 2.7 engine. Using what you have is always a reasonable option if engine longevity is not priority. I noticed that the case doesn't have CaseSavers so limiting clamping force will help prevent stud pulling.

Just for fun, if you haven't already rebuilt the heads, can you post a few pictures of the sealing surface?

[911pcars]

Originally Posted by Henry Schmidt

I'm guessing by the pictures, that's a 2.7 engine. Using what you have is always a reasonable option if engine longevity is not priority. I noticed that the case doesn't have CaseSavers so limiting clamping force will help prevent stud pulling.

Just for fun, if you haven't already rebuilt the heads, can you post a few pictures of the sealing surface?

Hi Henry,
It’s actually a 3.2. I may have to risk that possibility. I’ll keep my fingers crossed though.

[Henry Schmidt]

Originally Posted by 911pcars

Hi Henry,
It’s actually a 3.2. I may have to risk that possibility. I’ll keep my fingers crossed though.

Well I missed that "2.7" guess. Of course studs pulling on a 3.2 is not an issue.

Any chance of head pictures?

[911pcars]

Originally Posted by Henry Schmidt

Well I missed that "2.7" guess. Of course studs pulling on a 3.2 is not an issue.

Any chance of head pictures?

Henry,
Not many and none of the combustion chambers. Heads were rebuilt (guides, etc.), nothing special. Went as far as rebuilding the rods (w/ARP fasteners) and replacing rod bearings.



Sherwood

[Henry Schmidt]

When you rebuilt the heads did you machine the sealing surface?

[911pcars]

Yes. Took a little off +.

[Henry Schmidt]

Originally Posted by 911pcars

Yes. Took a little off +.

Why?

[911pcars]

Why? To clean up the sealing surface and to incrementally increase the compression ratio. I recall 0.025". Oh, and a set of 964 cams in the aforementioned 3.2.

Years ago, I did the same with my modified 2.0>2.7 w/S heads with E cams and RS pistons and their optimistic 8:1 CR. It worked fine if not noticeable

Shouldn't have? If I asked if I should have done more, might I have expected a resounding yes?

[Henry Schmidt]

Originally Posted by 911pcars

Why? To clean up the sealing surface and to incrementally increase the compression ratio. I recall 0.025". Oh, and a set of 964 cams in the aforementioned 3.2.

Years ago, I did the same with my modified 2.0>2.7 w/S heads with E cams and RS pistons and their optimistic 8:1 CR. It worked fine if not noticeable

Shouldn't have? If I asked if I should have done more, might I have expected a resounding yes?

No judgement, just interested in whether or not the sealing surface was damaged. Generally when we disassemble engines with Dilivar studs, head to cylinder movement creates a need to surface the heads. I was hoping you had pictures.
Although I never replace rod bearings without splitting the case, it sounds like you're doing a great job.

[911pcars]

When I disassembled the top end, I didn't notice any appreciable erosion of the cylinder head sealing surfaces. It was a running engine with typically worn valve guides. No other apparent issues.

Keep up the good work.

Sherwood