Bolt torque discussion

krazykuda said

You have to be careful on what type of oil that you put on them... different oils have different lubrication properties and can affect the clamp load for a particular torque...

80% of the torque value is influenced by the friction of the fastener....

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And the finish surface on the threads makes large difference too, as well as any plating.

What most users do't realize with the ARP's is that they are not going up by 40-50% or in bolt tension/clamping force by going from, say, 85 to 130 ft lbs torque. Because the ARP lube is so much slicker than oil, the torquing friction is a lot lower and it takes lot more tension in the fastener on on the threads to get the torque friction up. The actual force achieved is somewhere in the 100% higher range over what the stock fastener torqued to 85 ft lbs with oil would achieve. That is a very rough number but you are in the ballpark with that %.

IIRC (and this is going back a while): The threads in the cast block are considerably stronger than the steel bolts/studs. Again, IIRC, this is due to the material properties of the cast iron.