Overtighen ARP studs....bad idea?

[darrenjlobb]

Hey guys,

Have just had to strip half my new engine down again due to a bust water hose behind the engine....I am running ARP studs, torqued to the recommended 105nm at the moment, im pushing the engine pretty damn hard, will this be ok, or is there any advantage / harm to torqueing them down some more for peace of mind? If so what do you wrekon? i think ive read someone on here half problems with it blowing past, until he torqued them some more....

[theman53]

Yep just about everyone is torquing the studs higher than reommended by ARP. Those were for a gasoline engine, 53willy's did his to 110 ft/lbs = 149nM
most are going 100 ft/lbs = 135nM

I don't think you would want to go 120 ft/lbs or more as I figured one time that around there it would be too close to its yeild point of the chromoly alloy they used and probably wouldn't hold up to the cyclic fatigue at that point.

You should be fine to 100 ft/lbs.
You are using a MLS gasket correct? The fiber shouldn't take that much to get it to seal, but it won't take the boost like the MLS will.

[OM617]

Bolts work as strong springs. Like a coil spring, if you stretch it too much it becomes less effective.

I'd bet ARP knows what they're doing since they make the bolts themselves and have done far more R&D than everyone combined on any forum.

[theman53]

I think what he ^ is saying is take the MFG's word for it.

Must work fine for ARP, but not for K&N...Oh well.

Like I said and if you want to do your own research go ahead. ARP puts specs on the chromemoly alloys they use. It will be fine to over torque, but at 120ft/lbs it is at the point where the alloy is at its yeild point. Then it won't handle the cycles of constant fatigue. If you go to 100 ft/lbs like many have on here you should have the best of both worlds. Even just regular carbon steel 12.9 socket head cap screw will handle 100ft/lbs of torque and should be at 80-90% stretch.

8740 CHROME MOLY: Until the development of today’s modern alloys, chrome moly was popularly considered a high strength material. Now viewed as only moderate strength, 8740 chrome moly is seen as a good tough steel, with adequate fatigue properties for most racing applications, but only if the threads are rolled after heat-treatment, as is the standard ARP production practice. Typically, chrome moly is classified as a quench and temper steel, that can be heat-treated to deliver tensile strengths between 180,000 and 210,000 psi.

[OM617]

Must work fine for ARP, but not for K&N...Oh well.

No, ARP makes a high quality product proven to be better than the factory parts, K&N is just crap to waste money on.

[blackdogvan]

There is now a much stronger ARP option, they are dedicated for the TDI instead of a gasser motor stud that happens to fit. Check out Kermatdi, they seem to be the only retailer of them.

[theman53]

There was some bickering on the vortex about another or it was TDI club, but yes they do have a stronger alloy in this size. It is even more pricey as I think it was developed for a Cummins or something. I forget the alloy, but if I remember right it is about 10,000 psi stronger than the ones we have been using.

[8v-of-fury]

10,000 psi stronger than the ones we have been using.

Shizza

[blackdogvan]

There was some bickering on the vortex about another or it was TDI club, but yes they do have a stronger alloy in this size. It is even more pricey as I think it was developed for a Cummins or something. I forget the alloy, but if I remember right it is about 10,000 psi stronger than the ones we have been using.

Ya that thread on tdi club went nuclear... not so much about the studs, more about personalities.

[rabbitman]

Ya that thread on tdi club went nuclear... not so much about the studs, more about personalities.

The few times I've gone over there I've been very impressed with all the arguing, they seem to think thats the place to take out their anger .

[blackdogvan]

Ya that thread on tdi club went nuclear... not so much about the studs, more about personalities.

The few times I've gone over there I've been very impressed with all the arguing, they seem to think thats the place to take out their anger .

Yup, just reminds me how good this site is.

[clbanman]

There was some bickering on the vortex about another or it was TDI club, but yes they do have a stronger alloy in this size. It is even more pricey as I think it was developed for a Cummins or something. I forget the alloy, but if I remember right it is about 10,000 psi stronger than the ones we have been using.

Something has to be the weak link.  I would rather have studs fail than the threads in the block.