What does BDC refer to in an internal combustion engine?

BDC stands for Bottom Dead Center in the context of an internal combustion engine. This term refers to the position of the piston when it is at its lowest point in the cylinder. At Bottom Dead Center, the piston has completed its downward stroke and is about to begin its upward stroke toward the Top Dead Center (TDC), which is the highest point of the piston in the cylinder.

Understanding BDC is essential for grasping how the engine's power cycle operates, including the intake, compression, power, and exhaust strokes. The position of the piston at BDC affects various engine functions, including the timing of valve openings and closings, the air-fuel mixture entering the cylinder, and the overall efficiency of the combustion process.

Recognizing this terminology helps in diagnosing engine problems, performing service tasks, and improving engine performance, making it a fundamental concept in the study of internal combustion engines.