A four-stroke gasoline engine cylinder has a total volume of 450\text{ cm}^3 when the pist… — Armed Services Vocational Aptitude Battery (ASVAB)

A four-stroke gasoline engine cylinder has a total volume of $450\text{ cm}^3$ when the piston rests at bottom dead center (BDC) and a clearance volume of $50\text{ cm}^3$ when the piston reaches top dead center (TDC). What is the compression ratio of this cylinder?

A
$8:1$
$9:1$ Answer
C
$10:1$
D
$14.7:1$

Answer

The compression ratio of the cylinder is

9:1

The compression ratio is defined as the ratio of the total cylinder volume when the piston is at bottom dead center (BDC) to the clearance volume remaining when the piston is at top dead center (TDC). Dividing the maximum volume (

450\text{ cm}^3

) by the clearance volume (

50\text{ cm}^3

) yields

9

, representing a compression ratio of

9:1

Step-by-Step Solution

Identify the total cylinder volume when the piston is at bottom dead center (BDC) and the clearance volume when the piston is at top dead center (TDC).

Total maximum volume

V_{\text{max}} = 450\text{ cm}^3

and clearance volume

V_{\text{clearance}} = 50\text{ cm}^3

Compression ratio compares the largest cylinder volume to the smallest cylinder volume throughout the piston stroke.

Apply the compression ratio formula:

\text{Compression Ratio} = \frac{V_{\text{max}}}{V_{\text{clearance}}}

\text{Compression Ratio} = \frac{450\text{ cm}^3}{50\text{ cm}^3} = 9

This calculation determines how many times the cylinder volume is compressed as the piston moves from BDC to TDC.

Format the resulting quotient as a standard ratio.

9:1

Engine compression ratios are expressed as the ratio of maximum volume to minimum compressed volume.

Key Concept

Engine Compression Ratio Calculation

Estimated Time:1m 0s

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