Non resusable bolt

When we build an engine with oem nonreusable bolts how we torque the main bearing and rod bearing to the torque required? if we torque as much as the oem manual indicates can they be reused when we assembly the engine???

I assume you mean those bolts that are taken to their yield point, ie, a given torque value and then tightened a specific angle?

No, because they have already been tightened to the point where they have started to stretch - deform - and so re-using them will give a false value as they will be stretched twice, and the second time may have a different tensile loading.