Dictionary

Degree of compression is the ratio of the volume of the piston space above the piston at the bottom dead center (BDC) to the volume of the cylinder piston space at the position of the piston at the top dead center (TDC), i.e. to the volume of the combustion chamber. The concept of degree of compression shall not be confused with the concept of compression, which means (with a certain structurally determined compression ratio) the maximum pressure created inside the cylinder when the piston moves from BDC to TDC (for example: degree of compression - 10: 1, compression -14 atm).