The Engine Bottom End, is basically every part, that exists below the cylinder head gasket.
And, is by far the most important part of the engine. But, it is not just one thing. Because, it is made up of its own list of parts.
Furthermore, not all engines are the same or even include, the same parts. Consequently, most of that depends on the year, make, model and engine size.
The Engine Bottom End, is made up of a casting called, the engine block. Usually made from an aluminum alloy on modern cars, on older vehicles and trucks it was commonly cast iron.
Its metal construction gives it strength and the ability to transmit heat from the combustion processes to the integral cooling system in an efficient manner.