Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

Do you have any respect for a time cert magnesium case with dilavar and 22yrs before a failure of the fastener? Think about bit for a minute. Let it sink in.

Now.

Thoughts?

If you want this thread to be a defense of Henry then you're in the wrong place. I'm sure his messiah studs will work just as well with steel cylinders. You don't need to defend him because he is not being challenged. This is not about him. Get over it.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

You're not adding anything constructive to the thread other than bait for a fight. Please accept my invitation to leave while you still have your dignity good sir.

-Andrew

Question....in these cases...do the stud holes extend into the sump area...or are they blind holes?
My thinking...if they extend into the sump....it might be possible to install a "T" shaped insert from the inside.
This would spread the load to a larger area....and prevent any pull through of the stud or the insert unless the whole area cracked and broke.
Once again...brain working overtime.
Bob

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

Hi Bob,

These are blind holes. I like there thought of a wide anchor behind capturing similar to the head end of the stud provided there is no interference concern within the case. I believe you may need a left hand thread so tension would not be lost and an o-ring similar to the through-bolts.

-Andrew

I want to thank Lapkritis for this thread, and for sticking to the high road. There is a lot more than meets the eye to this problem. I got your 6 sir.

I'm just curious on why you picked the 2.7 engine, there are better ones out there, 3.2/3.6 come to mind. Is it period correct? money restrictions? race application? daily driver? seems to me a proven track record is worth a lot more than re engineering a product.

oh yes, even aircraft engines fail sometimes, IO470 head popped off, there screwed into the cylinder.
http://forums.pelicanparts.com/uploa...1363638686.jpg

When we started on the stud project, we didn't whine about challenges.
The material we started with was found in a 935 engine I acquired many years ago.
We studied the issue (years of engine building, discussion with colleges and assessment of what worked and what didn't) then gave what we learned to an engineering firm that specialized in fasteners, along with the 935 stud.
Then we produced the first sets of studs and tested them in our own race engines.
As we discovered deficiencies we adjusted the design.
This went on through seven difference iterations. This lasted three+ racing seasons.
Then before offering it to the general public, we started installing them in customer engine with a life time warranty.
It was only after 60+ engines and zero failures, that we started offering it to the general public.
Now Pelican Parts is our largest single customer. Most of the direct sales we do are to well noted/ respected Porsche engine builders.

When you're ready to develop your theories to the degree that we are, perhaps you"ll gain some respect.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

This is not a thread about your studs. It does sound like you did your homework though which is not in question. Thanks for posting and not sharing words of discouragement.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

I could have purchased a 3L or larger aluminum case engine by now. My reason for staying 2.7 is because I don't really care how fast the car goes. My Jetta was my foray into serious power and I don't need the complications with the 911. The 2.7 is original to my car, numbers matching and is well maintained. I would prefer numbers matching and confidence beyond a fastener that works with a case saver. Doing my own homework here isn't my first rodeo. I will gladly work the numbers for the supertec stud to take the whimsy out of these silly posts from the retailer. The fact of the matter, and which is the issue at hand, is the plausible deniability of the forces exerted on the case by aluminum cylinders in the condition that includes the use of non-dilavar studs. The math shows you're yanking on the case and testing the limits. It is my thesis in this thread that a magnesium case will be under far less stress with steel or iron cylinders. The math is simple and agrees. The world was once flat gentlemen. There was also a time where we didn't consider the cylinder in the solution set for keeping the magnesium case together. I for one can't believe this hasn't been discussed before. Perhaps the naysayers prior to this prevented testing? Won't happen here so the words of discouragement by a few are wasted.

-Andrew

Ok...this is hard to explain...but here goes.
I once took a motorcycle engine apart (single cylinder 500cc) and found that the studs screwed into the block (aluminum) with a steel plate inserted at a 90deg plane to the cylinder about 1/2" down from the top of the block/cylinder hole.
Whew...
Apparently...the slot containing the steel plate was cut from the bore into the block...and a steel plate was pressed in...then the hole for the stud was drilled and threaded resulting in a steel reinforced stud hole.
One of the plates was a little loose...and when I removed it to see what it was...I noticed it was basically a woodruff shaped plate with the threaded hole in roughly the middle.
It occurs to me...the this also might be a permanent answer to pulling studs.
All it would take is a cutting tool...like a milling cutter...to cut a slot in the side of the bore...and press in the steel plate...then re-tap the stud hole.
How about it?
Bob

If you were paying attention, you would have noticed that temperature control is one of the necessities when it comes to 2.7 longevity.
Porsche did away with cast iron cylinders because they (cast iron cylinders) are detrimental to cooling.
Even as early as the 356, Porsche realized that cooling the cast iron cylinder was difficult.
The reason no one has played with 90mm cast iron cylinders was because they don't work well.
QSC built them because they had a cast 356 cylinder in the works and found making the 90mm cast iron cylinder was cost effective (read cheap). As one of the contributes to the QSC design and testing team early on, I saw that they produced products with little or no understanding of the synergy of a complete air cooled 911 engine. They actually sell some of my products without understanding what they do or how they work.

They even produced an 86mm Nikasil cylinder that was molded from a 2.2 (84mm) cat iron pattern. The product failed almost immediately. The failed cylinder was sent to an engineering firm that performs critical analysis on aircraft parts. They suggested an anomaly (suggesting that the cylinder in question was dropped) and that the cylinder design was sound. It wasn't until my staff analyzed the cylinder was the errant design discovered. Sometime an understanding of the practical use is most valuable than engineering principles.

[Subtle Hijack]

http://upload.wikimedia.org/wikipedi...nce-people.jpg

[/Subtle Hijack]

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

The cast cylinders from QSC and the JB sleeves are not the only options I'm considering Henry. I believe it can be done for far less than $3g with USA materials which might help bring JB down to a more palatable level for folks. I could be wrong and discover costs are too high after a prototype set. Perhaps you would finally agree this can only serve to benefit the magnesium case crowd.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

Paying attention? Pardon me. Temperature and thermal expansion is the topic of this thread and perhaps you did not understand? The stack under your fastener is expanding at a different rate than your fastener. I had no idea this was hidden from the general public or simply not disclosed. This difference in expansion rate is the same force that has been pulling threads for decades. This is the conversation. We want to reduce these forces. Temperature relating to ring gap/piston wear/oil temperatures are assumed as solved or known. Those are also old challenges. You can run a large aftermarket oil cooler. You can run an appropriate ring gap for the slower expansion of the iron/steel sleeve. Your continued objections are like the crew of Columbus' ships saying they can't sail back to Spain because it's too far.

-Andrew

We played with 90mm Biral barrels years ago with no positive effects on head stud clamping. We cured the head stud issue and moved on.
We do use an 86 mm Biral on our 205 hp 2.45 but not as a budgetary concern. We use it the preserve the small spigot size on matching numbers early cases.
In fact, to create a reliable part, we Nikasil the cast iron liner.

An increase in clamping pressure is desirable. This is the point. Start with a predictable clamping pressure when cold and achieving the desired clamping pressure when hot. We have achieved that goal and stud pulling is no longer an issue as long as the hp limits (learned through experience) are maintained.

BTW: you're no Columbus and the new world you seek has already been discovered. You're beating a dead horse.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

Obviously not possible to win friends with naysayers. You prove them wrong and they eat crow or they come around. Henry and his posse aren't going to change physics and I won't drink the punch ignoring what I now know. I'd like to share my discoveries with other magnesium case owners for their benefit.

The contents of this thread just shows how much debate this subject continues to create and the same old arguments just keep going around.

Every debate starts with the same statement about studs and this is where I start to disagree.

I believe that the only studs that have ever caused concern are early Dilavar which are reported to fail due to either Hydrogen Embrittlement (HE) or Stress Corrosion Cracking (SCC).

This is a completely seperate issue to studs pulling which is concerned with the strength of the case and has little to do with the stud.

I would like to understand why the stud needs more clamping than the design requirement speified by Porsche and just what level of preload is needed.

To provide this additional clamping force using the expansion of the cylinder would be an unusual design concept, it would also not be reliable whilst the engine was warming up.

I have a problem with the idea that the stud has been 'designed' to provide the ideal level of clamping when the engine is hot as the expanisons are controlled by materials and not by stud design.

It is also interesting that Porsche were using 17-4PH in 1975.

17-4PH is an interesting choice for a stud material. There is nothing unique about the properties of 17-4PH in terms of coefficient of expansion, strength or corrosion resistance but it does have a good balance of these propeties at a very modest cost.

The most appealling aspect of 17-4PH is its ease of fabrication and has led to its inceasing use since its commercial introduction in 1969.

In detail I would prefer to use 15-5PH which would provide the same level of strength and eliminate any chance of sensitivity to SCC as can occur with 17-4PH when used in a very high strength condition.

I do accept that case savers and steel studs can solve many of the problems of mag cases and this is a practical solution but I agree with Andrew that this is a result of trial and error and not a process of design in the accepted sense.

This is not a pissing contest or a launching pad for the Friends Network.

It's called the 911 Engine Rebuilding Forum.

I come here and offer my experience to assist people trying their best to get through a rather difficult generally first time experience.
I come here to make that experience a success for the most people possible.

When people with little or no experience at successful Porsche engine rebuilding challenge well established practices with wild ass assumption and theories based in conjecture, the results quite often distribute inaccurate information and perpetuate false urban legend.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

This does not meet the definition of conjecture. We are using basic math and physics which is the exact opposite. We're bringing data to a topic cloaked in "just trust me" speak. I do not feel it necessary to tout my automotive hobby resume in order to have facts accepted as fact as I present them. The expansion rate of steel is less than aluminum. You don't need to "build" 10,000 Porsche engines to learn that. Your argument and moaning will not change that fact.

-Andrew

I am not sure to describe the expansion of metals as a 'wild ass' theory or conjecture is sensible.

As far as I know there has been no challenge to established practice just a request for a better explantion of the solution.

The situation is quite clear:

If we ask Porsche what to use they say Dilavar.

If we ask ARP they tell us that the more we pay the better the stud and the better the solution.

If we ask Raceware they tell us they make the best studs as do Casper Labs and so does Supertec.

I am sure every individual organisation selling studs has a firm belief in their product but there has never been a qualified answer as to the engineering behind the 'best solution'.

When we try to use basic engineering principles to see if a reason can be found or sense made of the agruments it just ends up with a bit of a rant which doesn't help anyone.

Henry, I wish you well selling your studs but I do refuse to accept some of the engineering statements you make.

I am sure you have built many 911 engines and I have, in the past purchased several of them and recommended you to many UK based customers but some of the rest of us have a lifetimes experience in both Materials Behaviour and Real World Engineering at the very highest level and it would be helpful if you could ocassioanlly recognise this fact or you will merely stifle all debate.

Chris, please name the engineering statement I've made that you don't accept.
Please remember to use an exact quote.

I would need to see the numbers before I could agree with this statement.

I don't really accept that an increase in clamping force is desirable as increasing load will cause more damage to the case material.

I don't really believe that you can obtain the 'desired' clamping force as you have no control of the relative expansion of the stud.

As Karl Popper famously said “Our aim as scientists is objective truth; more truth, more interesting truth, and more intelligible truth"

I just can't escape from tyring to understand more about some of these issues and the reasons for the solution and am happy with any sensible objective debate.

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

We are designing the sleeve/billet cylinder now. I am also going to test out the QSC 92mm set in the interim to determine if they are worth their weight in scrap or not. For all I know, they could all be tied together and used as a boat anchor or perhaps they spec out. I will share honest feedback here.

As a professional mechanic all my life I have always adhered to the tenant that you should always be smarter than the car (or engine) that you are working on. And for the most part I have always tried to be smarter...but as a professional who specialized in computer diagnosis and emission repair I was paid to fix the car...even if the repair or parts required didn't make sense diagnostically. In the real world the customer wants the car fixed---as soon and as cheaply as possible.
As a result I can sympathize with Henry's attitude. I am interested in the engineers cause and effect--but I have seen enough engineering solutions over the years to be skeptical . I have used steel studs since 1971--my experience with dilivar has been (like Henry's) that they do not provide enough clamping force ---and break. I have used ARP's--but did not use the 36 lbs torque value..(they must be crazy---no Porsche guys on that engineering staff) and was more than a little irritated when one of the studs gaulded on installation and I played hell getting it out of a very valuable early aluminum race motor case--then had to insert it.
I have used Jim's JB birel cylinders and they are very nice pieces--but heavy--and I feel that the LN cylinders are just as good --and considerably lighter.
I have an adequate inventory of early steel studs--but when I run out I will be calling Henry.
aws

Re: Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?
 

Still digging into information on the materials. Here's some basic information on heat transfer of materials in engines:

http://www.engr.colostate.edu/~allan/heat_trans/page4/page4f.html

This shows the values of convection for various materials that are most common. Cast iron has a lower rate of transfer than aluminum which many with experience will have already known. The challenge of a cast iron cylinder and cast iron heat sink will depend upon the oil cooler as well as the effectiveness of the fan and sink design. The best test set would be to monitor not only the cylinder temperature but the head/cam tower temperature and compare/contrast to aluminum vs. cast iron cylinder. If there is an overheat problem present with the cast iron heat sink then it will show up during monitoring/testing.

Qsc look fine and measure dimensionally as a very near match externally within .006mm on my caliper for critical dimensions. The jugs are going to have the bore confirmed as true at my machine shop. The pistons appear to be a replica cis which means aftermarket cams with additional lift will be a problem unless you want to machine the valve reliefs. I have new webcam GE40 so I plan to opt for confirmation of combined maximum dimension before custom ordering JE and honing the smallest 5 cylinders to match the largest if necessary.

Stock lift cams would probably be fine with the provided pistons. Rings are Grant brand. Pistons were inspected and found to be crack free. Should make for 6 wobbly ash trays.

http://i458.photobucket.com/albums/q...ps599ce9ab.jpg

http://i458.photobucket.com/albums/q...psfe14c2ba.jpg

http://i458.photobucket.com/albums/q...pscf125090.jpg

Mahle RS and qsc side by side:
http://i458.photobucket.com/albums/q...psb7a621f2.jpg

Qsc 92mm 9.5:1 911 piston:
http://i458.photobucket.com/albums/q...psb3f06553.jpg

http://i458.photobucket.com/albums/q...psa72d94be.jpg

I couldn't find any pictures of these parts when I searched the web so hopefully future travelers will learn from this thread.

That's all the update for now and until I have the cylinders from the machine shop and the custom je pistons in hand.

Your pictures bring this to mind: Looking at J&Es website, it would appear that you can order pistons with circlips for wrist pin retention, or several other means of retention. Considering the trouble dealing with other wrist pin clip types, why would not circlips be the favored part for this task?

I did once have a problem with a circlip in this function. In some manner entirely mysterious, one tip of one of them, out at the hole, broke off. The clip continued to do its job. Alas, the hardened steel tip did a job also - of etching the cylinder, first on one side, and then after traveling through the wrist pin, on the other, and so on. Had this been a more open slipper skirt design piston, the piece would have fallen into the case immediately, and most likely done no harm at all. But the wrist pin ended in a slot, not open space, so it couldn't escape.

I can't imagine what would have created a force on the tip of the clip, but something did. In time honored manner, on hearing this tale a shop owner said he never reused circlips. But nowhere have I ever seen that advice, before or since.

Walt...personnaly I like Spiral-locks for wrist pin retention.
They a total pain in the behind to install...and even worse to extract...but...they work...and never seem to fail...even in a fuel engine that has blown the heads right off!
Bob

We used to build a number of Coventry Climax based engines that rev to 10 000rpm and produce around 110 BHP/litre.

Theu have always used pistons with conventional circlips and these do commonly cause problems.

We routinely fit Teflon Buttons into these engines and they slove all of the issues in a cost effective manner.

Until recently I hadn't realized that spiral locks were a pain. Just the opposite of what I want, as I waste way way too much time in both directions dealing with the J&E regular locks, even with the tool for installation.

Chris - were the problems you saw with circlips retention failures? Obviously, that trumps ease of assembly.

But the pistons on my three race motors can't use Teflon buttons, either as primary or secondary retention devices, as the wrist pin hole does not extend all the way out to the cylinder wall.

Haven't had any issues with normal pin locks such as these:

http://www.fourseasontuning.com/parts/071107065c.jpg

Removal takes a steady hand and some care but once you've done a few they're fairly easy to work with. I haven't used spiral-locks before but they look like a nightmare to work with. :cool:

For those of you reading this thread and hoping for success in your build, here's what we do.
Assess the case condition. Like everything else in the high performance world, parts have a finite life. A mag case that has been super heated or experience the stress of prolonged racing is not an appropriate candidate for a successful rebuild. That means clean ,clean, clean and inspect.
Check line bore to insure proper bearing crush and oil pressure retention.
Dry film moly on factory bearings.
Improve oil flow to promote cooling and engine life. By-pass mod and pump flow mod.
Cross drill crank and boring feed hole to #4 main to promote increased oil flow to # 2and #5 rod bearings.
In this engine we removed the ill advised Timecerts and replaced them with the appropriately size CaseSaver. They come in at least 4 different sizes.
Professional installation is advised to prevent "porcupine head studs".
Deck the spigots and machine the bore to clean up any anomaly in the bore from installing the CaseSaver.
Timecerts have proven a reasonable repair for the 8mm perimeter studs.
We insert the 4 stud around the #8 main bearing and the long 8mm that clamps the case around the intermediate shaft.
Use only Viton case through bolt o-rings (green).
Install Supertec head studs using the system recommended with the studs.
Use the gluing technique that comes with our case sealing kit. This gluing technique is available on this forum free of charge.
Replace oil pressure valves with update spring and pistons.
Install Nikasil cylinders to promote proper head and cylinder cooling.
Trim cooling tin to promote cooling.
Add a set of wide tensioner arms (we make a set that we believe functions better than the factory version) to extend tensioner life.
Using these techniques we build an engine that carries a 2 year-unlimited mile warranty.
Does it work every-time. Of course not, but it's the best we've found so far.

http://forums.pelicanparts.com/uploa...1364599197.jpg
http://forums.pelicanparts.com/uploa...1364599220.jpg
http://forums.pelicanparts.com/uploa...1364600051.jpg
http://forums.pelicanparts.com/uploa...1364600106.jpg
http://forums.pelicanparts.com/uploa...1364600753.jpg
http://forums.pelicanparts.com/uploa...1364600829.jpg
http://forums.pelicanparts.com/uploa...1364600942.jpg
http://forums.pelicanparts.com/uploa...1364601184.jpg
http://forums.pelicanparts.com/uploa...1364601213.jpg
http://forums.pelicanparts.com/uploa...1364601451.jpg

That's great. Be prepared to see an alternative implementing the same tips Bruce Anderson detailed as well as taking it a step further in matching a jug to stud without using Dilavar. Anomaly in the spigot from installing the case saver? That doesn't sound good. Could you share some pictures of such an anomaly as you mention?

http://i458.photobucket.com/albums/q...psd941dbcc.jpg

Viton in-hand from the host. The Victor reinz gasket kit comes with the blue seals.

Every qualified Porsche machine shop understands this process. One of the reasons the 2.7 stud pulls from the case is their proximity to the spigot.
Installing an expanding (self locking) insert that close to the spigot tends to move the material in the thinnest area. In a perfect world (hardly a magnesium case) we would want additional material but in the real world, we deal with facts.
A none issue that has 25+ years of empirical evidence to substantiate the claim.

You can see the machine marks in the picture below. The machine mark adjacent to the CaseSaver.
http://forums.pelicanparts.com/uploa...1364606505.jpg

BTW: For any of you thinking about using the lower priced/quality Victor Reinz gasket sets, the quality of many of the gaskets fall under the category of marginal and some are even nearly unusable. Pay special attention to the CE rings.

Now that you point out the machining I do see it in your original images you posted as well as the cert visible in the spigot area. The reason this would concern me is the benefit of a larger saver is partially the increased thread area of the larger diameter into the base material. If 20% of the larger threads are machined off because they poke into the spigot area then you're losing some of the paperwork benefit of the larger saver over smaller. Essentially the area where the saver protrudes into the spigot without case material to bind to it is free-balling.

Agreed with the Victor Reinz gasket statement - the case seals and green fiber valve cover gaskets are toss away parts in my opinion. I haven't bothered to inspect the CE rings yet ever since my plans changed not to use the RS Nikasil parts.

Let me ask you this Henry, as less experienced folks such as myself would like to know - have you tried steel cylinders on the 2.7L magnesium case with your fastener? If so, did you monitor oil temperature differences or cylinder head temperature difference relative to the aluminum cylinders? I understand all engines have a finite life cycle... however when engineered properly those life cycles can exceed our expectations. When there aren't ridiculous forces yanking the engines apart they can last almost forever even when driven hard. Plenty of cars exceed 1 million miles... Porsche should be able to do the same if we consider what is yanking them apart and address it.

Fun article:

Million-Mile Club: The World's Longest-Lived Cars - Popular Mechanics

Andrew - the threads of case savers or timeserts or even helicoils aren't cut off when the spigot is trued. The process of drilling, tapping, and especially, with the time certs and their roll tap, or whatever holds the case savers in, bulges the case metal between the insert and the spigot inward a little.

Sometimes this is so little that you can still get the cylinder in, it is just tighter and harder to work with. And I think the upward pulling of the head studs can cause the inserts to do the same thing - move a little spigot metal inward. You can see the spots, and sometimes you can see marks (superficial) on the spigot part of the cylinder. I don't think this causes the cylinder to get out of round.

Doubtless other times this is a real hindrance. Makes great sense if a guy has the tools to true the spigot. You can see how little is removed in Henry's picture.

Also, I suppose it hasn't escaped your attention that the T motors from 1970 through 1972 (maybe 73 also) were steel, with factory steel studs. You never hear of any of this being a problem. Aside, perhaps, from guys who may have hot rodded these motors a lot and perhaps didn't get the cylinder cooling they would have liked. Porsche dealt with this with the steel and cast aluminum fin Biral setup for their S (E also?) motors from that era. Also problem free. And all of these were mag cases - the earlier ones weaker than the 7R.