What is the compression ratio if the cylinder volume equals 70 cubic inches at bottom center and 10 cubic inches at top center?

The compression ratio of an engine is determined by comparing the volume of the combustion chamber at bottom dead center (BDC) to that at top dead center (TDC). The formula for calculating the compression ratio is:

Compression Ratio = Volume at BDC / Volume at TDC

In this scenario, the cylinder volume at bottom dead center is 70 cubic inches, and the volume at top dead center is 10 cubic inches. Using the formula, we calculate:

Compression Ratio = 70 cubic inches / 10 cubic inches = 7

This leads to a ratio of 7:1, indicating that the volume of the cylinder at BDC is seven times greater than that at TDC. This ratio is critical in understanding engine performance, as it influences power output and efficiency.

The correct answer, therefore, reflects the proper computation based on the given volumes, highlighting an essential aspect of how engines operate effectively.