When a cylinder head bolt torque specification requires that the fastener is first torqued, then turned through a further set number of degrees, what is this method known as?

The method described, where a cylinder head bolt is first torqued to a specified value and then further turned through a set number of degrees, is known as torque-to-yield or more commonly referred to in certain contexts as angle torque. This approach ensures that the bolt achieves a specific clamping force while also allowing for elongation of the bolt, which helps maintain the necessary tension under thermal and mechanical load conditions once the engine is in operation.

This technique is particularly important in critical applications like cylinder heads, where achieving the proper clamping force is essential to prevent leaks and ensure optimal engine performance. The angle of additional rotation helps to compensate for any settling or stretching that occurs when the bolt is initially tightened. Therefore, while the options seem to present various torque methods, the one that encapsulates the use of a specified degree of turn after initial torque application is not reflected correctly in the provided choices.

It's important to understand that the other methods mentioned—like dynamic torque, which refers to the force acting on fasteners during movement; or incremental torque, which typically involves sequentially tightening in stages—do not align with the specifics of the torque and angle method. Hence, none of them accurately describe this specific torque application technique.