engine terminology

The following are some of the technical terms that are used to describe features of the engine:

Engine capacity – the total, combined, displaced volume of all engine cylinders as a single value stated in units of cubic capacity. This is generally
given in cubic centimetres (cm3) or litres. In America, engine capacity is normally stated in cubic inches (in3).

Swept volume – the volume of a cylinder bore between the TDC and BDC piston positions, excluding the volume above the piston at TDC

Clearance volume – the volume above the piston at TDC. Note that it is the volume of the combustion chamber itself

Bore – the diameter of the engine cylinder.

Stroke – the total linear distance travelled by the piston in the bore between TDC and BDC positions. Note that it is twice the crankshaft throw.

Compression ratio – the total volume of the cylinder at BDC (swept + clearance volume), expressed as a ratio of the volume of the cylinder
at TDC (clearance volume).

The information on cylinder dimension can generally be found in workshop or manufacturer manuals. In addition, these values can be measured directly or derived via calculations

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.