What is the compression ratio of an engine with a bore of 89mm, a stroke of 88mm, and a clearance volume of 69.72cm3?

To determine the compression ratio of an engine, the formula used is:

Compression Ratio = (Cylinder Volume + Clearance Volume) / Clearance Volume

First, calculate the cylinder volume using the bore and stroke measurements. The formula for cylinder volume (in cubic centimeters) is:

Cylinder Volume = π × (Bore/2)² × Stroke

In this case:

• Bore = 89 mm = 8.9 cm (since 1 cm = 10 mm)

• Stroke = 88 mm = 8.8 cm

Now plug in the values:

Cylinder Volume = π × (8.9 cm / 2)² × 8.8 cm

Cylinder Volume ≈ 3.14 × (4.45 cm)² × 8.8 cm

Cylinder Volume ≈ 3.14 × 19.7525 cm² × 8.8 cm

Cylinder Volume ≈ 3.14 × 174.209 cm³

Cylinder Volume ≈ 546.015 cm³

Next, convert the clearance volume from cm³ to the same unit used for the cylinder volume, which is already in cm³:

Clearance Volume = 69.72 cm³

Now, use the values