Engine classifications

4.3.1 Classifications of Engines 

Engines can be classified according to different following characteristics:

• according to the type of fuel used: liquid and gaseous fuel; 
• according to the method of fuel mixing: with carburetion (carburetor engines and engines with multipoint fuel injection) and with fuel injection (diesel engines and gasoline engines with direct fuel injection); 
• according to the way the working cycle is performed: four-stroke and two-stroke; 
• according to the method of ignition of the gas-air mixture: with forced ignition (from electrical discharge) and with self-ignition (from compression); 
• according to the method of filling the cylinder: atmospheric of naturally aspirated (air enters the cylinder, which is sucked in by uncharging), and charging (air enters the cylinder with excess pressure); 
• according to the number of cylinders: engines may include from 1 to 12, or even up to 16 cylinders; 
• according to the arrangement of cylinders: in-line with vertical arrangement of the cylinder axis, V-type, VR-type, W-type, opposed - with a camber angle of 180° between the cylinders;  
• according to the cooling method: with liquid and air cooling. 

The types of engines will be discussed in more detail later, in the corresponding sections.