What's the best way to torque head studs on a 996t for high horse power applications. Is the workshop manual the best way?

 

If you are using aftermarket studs perhaps the stud maker offers a torque procecdure?

If not and if you are using go fast parts for a high horse power application then perhaps the company that offered the go fast parts might have a recommended stud torque procedure?

 

Most people say the ARP procedure is garbage. No one talks about a specific procedure which is correct. But everyone talks about using correct procedure, no one offers specifically what that is.

I can find info on what isn't good, but not what is. Hence the question. Maybe you have one that you use and swear by, maybe that's the ARP one?

Many people talk about a retorque after a heat cycle, no stud manufacturer states it, some say they don't need to do it, others say it's essential.

Just a discussion on what procedures people are actually using?! Please, no instruction copouts! The way people talk they are not being used anyway, that much is obvious.

 

If the ARP stud torque procedure is truely garbage that casts serious questions on the studs. If anyone has any skin in the stud torque procedure game it would be the stud maker. At least that's what I would think.

If you are using another brand of stud doesn't the maker offer a procedure? Or does it just say to use the factory procedure?

If you are using factory studs then I guess you are looking at using the factory stud torque numbers and procedure but I bet with almost every engine builder he has his own preferred procedure. Whether a professional will share this hard won knowledge with the general public (anyone... it ain't a secret if you tell someone) is another question.

If an aftermarket stud maker doesn't say anything on this subject referring to my statement above about skin in the game it would not give me the warm fuzzies about the studs if the maker didn't have something reasonally intelligent to offer on this subject.

"Oh whatever" is not a stud torque procedure I'd want to have to rely upon for such a critical step in engine assembly.

With my engine rebuilds -- no Porsche engines though -- and at least one engine mildly hopped up (high compression pistons) I just used the factory head torque numbers and procedure. I do not recall if there was a re-torque after some run tme called out or not now but probably not. Oh, I used factory head bolts too, but new ones.

If you want specific Porsche Turbo engine head torque experience then I am sorry I can't help you.

 

the retorque is a requirment of racewear studs. its in the instructions given with the studs. they also reset the torque from 45 ft/lbs to 60 ft/lbs since heads were lifting. the arp only use 45 ft/lbs and arent much stronger than stock.
evoms uses a 12mm stud that torques to 90 ft/lbs. this allows for a step torque procedure from 30 ft/lbs up to 90 ft/lbs and no need to retorque since even if the studs back out they will still hold the heads above 80 ft/lbs.

 

This such an "hot potato" issue its best left alone. I have read some of the posts about this and such fever has being added with respect to what is right. There is no right in my opinion now. One man's right is another man's wrong.

My advice to anyone wishing to change studs for whatever reason, do some due diligence, research and ask questions of those that sell these parts and those who use them.

No studs should be sold that cover all applications. And bought. If you are wanting to build a high horsepower engine, buy studs and parts that will do the job. If unsure ask!!

This is one subject that the DIY builder has to understand info on "what and how" may be limited. Those that do this for a living may be reluctant to give up their secrets on this subject. You are left with all of these differing opinions on what and how.

My only advice here is to do your research and make sure you fully understand all of the procedures involved. This is a full attention area of building an engine and no part of it should be taken for granted.

I wish I could offer more help, but as every engine and its application is different, each one needs to be addressed individually.

 

I would listen to any advice that contradicts ARP, IF that source is better qualified to speak on the subject of ARP studs . Who would be that brilliant source ..... ?

You are using an ARP stud kit - surely not OEM ?
And using the correct tools to torque them. No, your Dad's old Craftsman beam torque wrench is insufficient. And you are following all the other Instructions ARP gives ? ARP even supply little satchets of grease for the threads !
I think ARP know what they are doing !Me ? not so much ,which is why I follow their very clear Instructions.

 

Be careful here. Not all head studs are the same. Some are made and sold as OEM replacements and never designed for high BMEP's.

As for assembly procedures, no torque wrench old or new, good or bad should ever be used. Head stud nuts should be tightened by an angle method to ensure any friction is removed from the tightening procedure.

 

"No Torque Wrench" ????
Technical Advisor wrote:
"As for assembly procedures, no torque wrench old or new, good or bad should ever be used. Head stud nuts should be tightened by an angle method to ensure any friction is removed from the tightening procedure"

I beg to differ with our Technical Advisor" based on the ARP Instructions.
and Snap ON Instructions- see links below.

Yes you do use a Torque Wrench !!!! ARP tells you to.

First you torque to a specified force to preload the bolts.This preload at x lbs/ft is the only basis for the subsequent torque angle spec.

After the preloading is done, yes with a torque wrench, you use a torque angle meter.See Brownline for Instructions below.
This is basic,simple, Standard Procedure.

If you have a SnapOn Techangle,the torque setting and angle are achieved with the same tool using pre-sets. So Yes ,you use one tool -a Torque Wrench to set both torque and angle sequentially.
And Tech Advisor said : an "angle method to ensure any friction is removed". What ? There is friction on the threads of even a lubricated nut bolt.The important issue is that the special lubricant ARP supplies(+their Instructions) make that friction a constant ,not a variable.
With no friction(how?) it does not work.
http://arpinstructions.com/instructions/201-4303.pdf
http://www.brownlinemetalworks.com/p...DAG_Manual.pdf
http://www.snaponindustrialbrands.co...e%20Manual.pdf

Just follow ARP's INSTRUCTIONS is my suggestion.

 

i guess the porsche engineers dont know what they are telling every porsche technician in the world to do then. straight out of the porsche repair manual

Cylinder, cylinder head and camshaft housing
Note
The axial camshaft adjuster central screws (inlet camshaft) and sprocket wheel (exhaust camshaft)
must always be replaced.
•
10 01 00 Tightening torques for M 96/70 engine 385
Location Thread Tightening torque Nm (ftlb.)
Cylinder head nut (coat thread and sealing
surface of the nuts with engine oil)
M10 30 Nm (22 ftlb.), then unscrew; 20 Nm (15
ftlb.) (joining torque); then retighten all
screws to 20 Nm (15 ftlb.); final tightening
with 120° turn

 

I'm sorry. I guess I should have explained it better for those that maybe missed my points.

You are correct, you cannot eliminate the friction. The angle method accepts that friction is present but removed the friction coefficient from the tightening procedure. An angle is the same regardless of the friction present. Eg., 100° of angle is 100° with or without friction.

Any small amount to tightening that is initially done is to seat the part, not to stretch the fastener. Calling out very small amounts of a torque value is an amount that makes the assembly a little more procedural.

If you have some device that attaches to a Torque wrench or your torque wrench has an angle finder built in , then great. Use it. I'm certainly not advocating not to, my comment was that an angle method should be used not a torque method. Always make sure whatever tool you are using is accurate and calibrated against a standard.

Maybe I need to be more clearer in my comments for some. And, this is only a suggestion and its free.

 

im not sure how anyone would construe what you posted as anything other than what you posted "AS FOR ASSEMBLY PROCEDURES, NO TORQUE WRENCH OLD OR NEW, GOOD OR BAD SHOULD EVER BE USED."

regardless of what angle method is used your posting is inaccurate and wrong according to virtually every engine builder and porsche engineer in the world.

 

Technical advisor said:
"my comment was that an angle method should be used not a torque method."
NO ! ARP says this is wrong.Porsche says it is wrong.
. This should be edited out by the Moderator.

Just follow the ARP Instructions or the Porsche Instructions.Forget the Tech Advisor.He has clearly stated in simple English twice - to do exactly the wrong thing.

Both Porsche and ARP say use a TORQUE Wrench AND the angle tool.If both are combined in a single tool like the SNapOn ,you use the torque setting first to set the pre-load and then the angle.
As a Technical Advisor you have a duty to give either correct advice or none.Please edit your mistaken and misleading comments. God forbid some poor diy engine rebuilder follows them .He won't be as restrained and polite to you as I am when his cylinder head gaskets leak.
If in doubt call ARP in Ventura. They are real nice and helpful over the phone.

 

The original question was asked in reference to a high horse power application. I stand by what I suggested.

I "think" you will find that any suggested method by ARP and Porsche is referenced to a stock OEM application. Building high horse power engines is another field altogether and requires a totally different approach and set of engineering skills.

Further, I have read on this forum where ARP studs have had their ability to "hold" questioned. I have spoken to ARP about this and they agree that their studs as advertised are not for high horsepower applications and are sold as replacements for stock engines and use. If you are building any sort of high horse power engine, first you need to calculate the Cylinder pressures involved, the clamping loads required, and all of the other necessary calculations. Then ask ARP or any other stud manufacturer to build you a stud that will perform the task required. The correct choice of base material will then be used along with the design of the stud. The exact same fundamentals should be applied for heads studs as are for Rod bolts and other highly stressed fasteners. Companies will do this, if asked. They all have special departments just for these sorts of applications.

I was asked to offer technical "suggestions" for free based upon my knowledge and experience. No one has suggested you accept them nor do as I say.

Good luck with your build and remember an engine is the sum of its parts. So choose them wisely and ask questions if unsure. There are many ways that a successful engine can be built. Not one way only. If the way I suggest is not to your liking, that's Ok. After all, you are the builder or the builder you choose have to take full responsibility for your assembly procedures.

 

Here is the info on ARP studs for the 996TT.
https://www.amsperformance.com/cart/...-stud-kit.html
Here are the specific Instructions on the 996TT.
http://arpinstructions.com/instructions/204-4210.pdf
Please use them if you are rebuilding with ARP products.