ARP Head Stud Torque specs??

[sabretooth]

For what it's worth, with my ARP head stud kit, I went with 80ft.lbs. They actually made the bolt. Seemed like the smart thing to do.

58,000km later and no problems...

[toppertee]

I used 80 foot pounds on the supercharged car and 65 on the turbo one, both with NB heads. Who knows what is "correct" but neither have had any issues so far.

How did your gear box feel about it?

[timk]

I destroyed forth in a five speed box, but I think this is unrelated?? Or I don't get your bad joke?

[toppertee]

I destroyed forth in a five speed box, but I think this is unrelated?? Or I don't get your bad joke?

I thought it was a great joke, zoomzoom and I where talking about which gear box to run in my car He stated what happened to yours.

[Micca]

Could a change in torque fluid goo be the reason for a recommended torque change?

Sent from my GT-I9100T using Tapatalk 2

Yes, this is the reason! Lower friction co-efficient with the ARP Ultra-Torque lube compared to the ARP Moly lube. The ARP Ultra-Torque claims to reduce pre-load scatter to 5% therefore you don't need to put the bolts through multiple torque cycles to get even and accurate pre-load.

I know first hand that between dry and lubed there is a MASSIVE difference between given torque readings and bolt pre-load achieved from those readings and this is due to friction co-efficient differences.

ARP blurb on their new lube...
"Because of frictional inconsistencies with oil, moly, and other lubricants it takes multiple cycles of torquing the bolt, loosening it, and tightening it again to obtain the required preload or stretch. Typically, when a fastener is first tightened, friction is at its highest point and the preload value or stretch is low. As the fastener is cycled numerous times the friction decreases and the preload increases. This phenomenon is called "preload scatter." With this ARP Ultra Torque assembly lubricant, a fastener need only be torqued once to get within 5 percent of ideal preload, and it remains consistent through all subsequent cycles (from race-prep machining through final assembly). Moreover, given the inconsistencies of ordinary lubes, it is quite possible for adjacent head bolts or studs to have vastly different preloads. This scatter causes bore distortion, hampers piston ring seal, and leads to poor head gasket sealing."

So 60 ft lbs is right with the old ARP Moly lube but it is not enough to get adequate pre-load (worked out by ARP engineers based on stretch) with the new ARP Ultra-Torque lube.

If your builder has a tub of Moly that he's using, go no more than 65 ft lbs and re-torque after 10 heat cycles to even out pre-load scatter and relief. If he's gone over to the Ultra Torque stuff then bang em up to 80ft lbs and forget about it.

I would suggest that any other issues with cracking of an alloy head should be investigated further. If you used 30 weight oil or the old Moly Lube up to 80 ft lbs I'd recommend consider checking your head studs for stretch next time you have the head off because they may well be over-streched for sure.

[Micca]

Edit to above: My logic above when considering the engine oil doesn't really work in with ARP's specs to do it up to 85 ft lbs with 30 wt oil. I can only assume that this is due to decreased friction with the 30 wt oil. Should be fine up to 85 with 30 wt oil but not with the old ARP moly lube. Anyway hope this information is useful to some of you out there. Building up a BP GT-R Familia motor and saw that there was obviously a lot of debate on this issue. Just presenting my findings.

Cheers,
Micca

[Dweezle]

Thanks mate.

Appreciate it.

My brother and i are the Engine builder (Loosest possible definition of the term )

We have the engine in but i believe lil bro only torqued them upto stock figures.

Might be worth taking the cam cover off and retorquing them upto 80ftlbs.
We used the Ultra Torque assembly lube.

Would it be an issue to torque them now to 80ftlbs after then engine has heat cycled?
Ie- would the lube now be not working as it should from the heat?


Again thanks

[Micca]

Thanks mate.

Appreciate it.

My brother and i are the Engine builder (Loosest possible definition of the term )

We have the engine in but i believe lil bro only torqued them upto stock figures.

Might be worth taking the cam cover off and retorquing them upto 80ftlbs.
We used the Ultra Torque assembly lube.

Would it be an issue to torque them now to 80ftlbs after then engine has heat cycled?
Ie- would the lube now be not working as it should from the heat?

Again thanks

That's a very interesting question that I am not sure has a straight answer. However, in short, NO I would not re-torque them now. I know many just 'check' the torque and you are right that readings will differ (which I had not thought about) as the lube has been cleaned away somewhat by hot oil running in there. Releasing and re-torquing (which you would need to do to get new lube on them and an accurate final torque reading if you aren't just re-checking final torque) would not be a good idea on your head gasket.

So I would say leave it if you don't have issues. If you develop issues with head gasket seal, change it, remove and clean the studs, get the head checked and re-install the studs with the ULTRA-TORQUE lube and you're good to go.