Uprated head studs

[Dave]

Here is the best way to describe the difference in stock bolts and uprated one.

As you can see on the graph, the straight line between 0-100 indicates a linear tensile load/bolt stretch, as soon as the line starts to curve, then the bolt is being stressed to a higher load, but the extension is much more, causing it to yield, at this point, the bolt will not return to the normal length it started with if you were to release the load off it.

Basically uprated ones will be able to maintain the straight line for longer, meaning that they can be loaded more before they stretch, this being reusable and/or providing a higher clamp force. Stock bolts are designed to stretch past the yield point as thats where the maximum load on the bolts can be acheived, hence why we should in theory replace them, although I never have hehe, textbook tuners

edit: just realised this is a torque/angle graph, but the principles are applied in exactly the same way.