Bolts used for fastening bearing caps, they ensure correct operation of the engine crankshaft.
Bolts used for fastening the various components of the lower part of the engine and which constitute half of the main bearings (main bearing caps, half blocks, complete banks).
The same considerations made for engine head bolts apply, while taking into account that bearing cap bolts must withstand at least two screwing operations during the engine production cycle and must therefore be engineered to guarantee a more constant distribution of the axial load.
In designing them, the double tightening strategy which they are subjected to during cylinder block machining and crankshaft assembly must be carefully analyzed. Typical 10.9 and 12.9 strength ratings, more and more so they are designed with custom strength ratings, even with very narrow Rm ranges.
They work in the plastic range and are usually tightened based on torque + rotation. Depending on the architecture of the engine and its dimensions, they may have different head shapes, rarely require a washer. In most cases they are phosphated and oiled.