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Which upgraded head studs??

ragpicker

Well-known member
Joined
14 Apr 2013
Messages
4,062
Morning!

As usual I'm looking forward at the next round of work on my car. In particular I'm thinking about the head gaskets at the moment. I've seen a few posts over the years about the head gaskets being a common failure point on heavily tuned turbos 'they always leak' being the comment that sticks out.

I see EVOMS do a 10mm stud kit and a 12mm kit.

Also ARP do a kit which I believe was originally designed for the 993 turbo?

Anyone have any experience of these studs? Any recommendations as to which ones to go for with a car running about 1.5bar and no more than this?

Also is there a recommended gasket to go with whichever stud kit the great people of 911uk recommend??

Cheers

:thumb:
 
Im not sure regarding gaskets but some people also O-ring the heads on the 997tt.

As for head studs bare in mind afaik if you go with 10mm they need to be re torqued after a heat cycle which means removing the engine again...

Although 9FF offer 10mm stud that apparently don't need a retorque.

There are a few places offering headstuds, I know srm offers a 12mm kit along with the guide tool for drilling and tapping. The drilling doesn't take long... Supposed to be good to 1500hp.

I think ARP offer an 11mm stud, I remember reading of them stretching.

Evoms are pretty good with the 12mm and use the factory nuts.

There are also BBI, raceware, Proto, ES etc.

I also think the installation plays a big part in the strength too, preloading etc.
 
I have heard a few times that it is more about the correct installation of the studs than anything else. Obviously on very high power cars that could be different. I would worry about rods first. On standard rods I wouldn't worry about gaskets or studs.

MC
 
I think rods and studs go hand in hand, The most popular rods are the carrillo's but you need to shave the oil pump for clearance which again is only minor work.

The problem is the "while you're in there" list can just go crazy, 3.8, pinning cams, porting etc

Also if you take apart the valves, the list of not really reusable parts can be a rather high unexpected cost...
 
116618LN said:
Im not sure regarding gaskets but some people also O-ring the heads on the 997tt.

As for head studs bare in mind afaik if you go with 10mm they need to be re torqued after a heat cycle which means removing the engine again...

Although 9FF offer 10mm stud that apparently don't need a retorque.

There are a few places offering headstuds, I know srm offers a 12mm kit along with the guide tool for drilling and tapping. The drilling doesn't take long... Supposed to be good to 1500hp.

I think ARP offer an 11mm stud, I remember reading of them stretching.

Evoms are pretty good with the 12mm and use the factory nuts.

There are also BBI, raceware, Proto, ES etc.

I also think the installation plays a big part in the strength too, preloading etc.

Thanks for this dude, some excellent advice here.

its a tricky one then. The whole idea of having to pull the engine, remove the cams etc etc again just to re-torque the studs sounds like an absolute nightmare! What a bad idea that is. Its not so bad on the old air cooled stuff where you just take a bit of exhaust and the rocker covers off but to do it on a 996/7 turbo requires a lot more effort!

Likewise drilling out the studs sounds like a bad idea too but if it gets around the need to re-torque then it might be better...

I've had an email from RaceWear who say they sell 10 and 12mm studs but only recommend their 10mm studs because they are good to 1200whp at least. Unfortunately they say you have to re-torque them.

I'm worried I'm now at the point where things can go wrong - bent rods, lifted heads, leaking gaskets, slipping tip box etc etc so I can see the sense in upgrading the rods at the same time. it would be daft to do one without the other when they are both known to fail at around the same time, especially when looking at more power.

So an ideal solution would be direct replacement 10mm head studs which don't need a re-torque. From what you've said 9FF may do this so I'll drop them a line and see.

Other than Carrillo rods, are there any other options? Looking at PET it is possible to remove the rods and shells without splitting the crank case or removing the cylinders (i can hear the sharp intakes of breath) which can potentially speed the process up a little bit...

The research phase on these projects is often the most interesting!
 
There are also pauter rods, Im personally doing carrillo, the shaving of the oil pump is really not a big deal. I have also read that the pauter bolting area isn't great. Carrillo have a good history in big big builds.

I would go with the 12mm studs, the work needed for drilling and tapping only takes 3-4 hours. A friend has just installed the 10mm 9FF studs on a 3.8 build. I can report back in a month or so on how they're going, we are still tuning.

Im not sure what you're running but if you are on stock internals on the 997 platform I know that as long as you're keeping and eye on your fuelling (IDC), timing, keeping the torque down early and not doing any long full load pulls in higher gears I think you're ok. A few shops have been running 900whp builds on stock internals, I think proto had one at 960whp.

Ive been running 3071's with 1100cc injectors for 1.5 years, 1.45 bar on pump +meth (1.7 on 109/c16), in 30c to 50c and i've had no issues apart from a slipping box only recently.

My friend had the same set up and we have examined his old parts and no visible damage.

Although preventative maintenance and upgrades will always be cheaper :lol:
 
it seems that ARP head studs do not need a re-torque. Taken directly from their website: If you follow the ARP installation instructions, there should be no need to do a re-torque. However, it may be necessary under certain circumstances if the gasket manufacturer's instructions require it, particularly if a fire ring has been installed. ARP recommends not doing a re-torque on a hot engine.

http://arp-bolts.com/p/FAQ.php
 
I wouldn't go with ARP, multiple reports of stretching. I think there are good reports on raceware, so check them out too.
 
116618LN said:
I wouldn't go with ARP, multiple reports of stretching. I think there are good reports on raceware, so check them out too.

I've had a reply back from racewear who say they specify a re-torque...

As you say it looks like 9FF are the ones. I've emailed them and await reply. I can't find a link to the product anywhere.

I do wonder if the reports about ARP studs stretching is because they are so popular and other manufacturers haven't sold as many units to experience failures. They could have been installed incorrectly too. There is one very well known engine builder in the UK who uses ARP 10mm studs.

I haven't had my car dyno'd but was recently tuned by ES and is running approximate times to that of their ES650 package with big injectors, billet K16s, IPD, RS coolers and decat.

My motor is on 77k miles now and its only a matter of time before something goes.. Plus it'll give me an excuse to ask Emre to up the boost :grin:
 
Tbh I really wouldn't worry about studs and rods bending now, unless you have some really bad fuel or an actuator breaking.

My honest opinion would be to decide on who is building the engine, if it is someone like Emre, then go with what ever he suggests as he is a proven specialist builder who has tried every possible stud, piston etc.

The last thing you want to have is parts from all over and have an issue later on while tuning etc and everyone points there finger at each other.

Although I know parting the kit yourself can be miles cheaper... :D
 
Just to update this, i've had a reply from 9FF who say they recommend the 10mm ARP studs due to them being tried and tested and not having to re-torque them.

I asked them about their own studs but the above was the reply.

Its hard to know what to think because everyone seems to have a different opinion from the 'ARP ones are worse than stock', to a few well respected builders telling me the opposite.

I think for my purposes as long as the studs are tightened in the correct way the ARP will be enough.

:dont know:
 

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