Calculating Compression Ratio/Engine Displacement Practice Small Power and Equipment
Section 1 – Compression Ratio Calculate the compression ratio for a small engine given the following information (SHOW ALL WORK!!!):
Bore of the cylinder (B) = 105 mm Stroke of the engine (S) = 90 mm Compressed Gasket Thickness (Gt) = 3.5 mm Bore of the gasket (Gb) = 93.5 mm Volume of the combustion chamber in the cylinder head (Vcc) = 50 ml Gross Piston Head Volume (Vphg) = 80 ml Piston Depression (Pd) = 25 mm
Item Symbol Formula Formula Result Applied Depression Vdp B x B x Pd x F Volume
Net Piston Vph Vphg - Vdp Head Volume
Gasket Volume Vg Gb x Gb x Gt x F
TDC Volume Vtdc Vcc + Vg + Vph
Swept Volum Vsw B x B x S x F e BDC Volume Vbdc Vtdc + Vsw
Compression CR Vbdc / Vtdc Ratio
Calculating Compression Ratio/Engine Displacement Practice Small Power and Equipment
Bore of the cylinder (B) = 110 mm Stroke of the engine (S) = 75 mm Compressed Gasket Thickness (Gt) = 1.5 mm Bore of the gasket (Gb) = 80.5 mm Volume of the combustion chamber in the cylinder head (Vcc) = 50 ml Gross Piston Head Volume (Vphg) = 88 ml Piston Depression (Pd) = 15 mm
Item Symbol Formula Formula Result Applied Depression Vdp B x B x Pd x F Volume
Net Piston Vph Vphg - Vdp Head Volume
Gasket Volume Vg Gb x Gb x Gt x F
TDC Volume Vtdc Vcc + Vg + Vph
Swept Volum Vsw B x B x S x F e BDC Volume Vbdc Vtdc + Vsw
Compression CR Vbdc / Vtdc Ratio
Section 2 – Engine Displacement (5 points each = 10 points) Calculate the engine displacement given the following information (SHOW ALL WORK!!!).
1. Bore = 250 mm Stroke = 110 mm Cylinders = 4
Calculating Compression Ratio/Engine Displacement Practice Small Power and Equipment
2. Bore = 100 mm Stroke = 85 mm Cylinders = 2
3. Bore = 126 mm Stroke = 100 mm Cylinders = 4
4. Bore = 105 mm Stroke = 90 mm Cylinders = 1