Engine Displacement

Engine displacement is a term we have all heard before but what exactly does the term refer to? The term displacement generally refers to the weight or volume of a fluid displaced by a floating body. Used mostly when describing the weight or size of a ship. An example of this principle is when you sit in a bathtub the water level rises because your body physically displaces the water.

Engine Displacement When you talk about the size of an ATV for example you may say you have a Honda 450 or a Can Am 800. When describing a car engine you may say that it has a 350 or 5.7 liter motor. What do these numbers refer to? All these number are actually describing your particular engine’s displacement.

Engine Displacement Here the 450 and 800 is a volume given in cubic centimeters. This is a metric measurement of volume. In today’s cars the engine displacement is given in liters. Such as a 5.7 liter hemi. Before Canada switched to the metric system or if you read a brochure from an American car manufacturer they my describe an engines size using cubic inches.. Such as a 350 cu in.

Engine Displacement In simple terms we can determine an engines displacement by calculating the volume of its cylinder or cylinder(s). The formula for the volume of a cylinder is pi x r 2 x h

Engine Displacement Pi = 3.14 R = radius of the cylinder or ½ the diameter and then squared (Diameter of a cylinder referred to as its bore) H = height or full travel of the piston or a stroke.

Engine Displacement Here is an example; What is the displacement of an engine that has a piston travel of 3.250” and a cylinder bore of 1.500”? Pi x r 2 x h 3.14 x (1.500/2) 2 x 3.250” 3.14 x (0.75”) 2 x 3.250” 3.14 x ” x 3.250” 5.74 cu in

Engine Displacement Try these examples; 1) Piston travel is 2.75”, cylinder bore is 1.250” 2) Piston travel is 1.75”, cylinder bore is 1.500” 3) Piston travel is 3.25”, cylinder bore is 1.750” 4) Piston travel is 2.00”, cylinder bore is 2.25” 5) Piston travel is 5.75”, cylinder bore is 4.75”

Engine Displacement Solutions: 1) 3.37 cu. in. 2) 3.09 cu. in. 3) 7.81 cu. in. 4) 7.95 cu. in. 5) cu. in.

Engine Displacement