Classification of Internal Combustion Engines

There are many different types of internal combustion engines. They can be classified by:

1. Application

Automobile, truck, locomotive, light aircraft, marine, portable power system, power generation

2. Basic engine design

Reciprocating engines (in turn subdivided by arrangement of cylinders: e.g., in-line, V, radial,

opposed), rotary engines (Wankel and other geometries)

3. Working cycle

Four-stroke cycle: naturally aspirated (admitting atmospheric air), supercharged (admitting precompressed fresh mixture), and turbo- charged (admitting fresh mixture compressed in a compressor driven by an exhaust turbine), two-stroke cycle: crankcase scavenged, supercharged, and turbocharged.

4. Valve or port design and location

Overhead (or I-head) valves, underhead (or L-head) valves, rotary valves, cross-scavenged porting (inlet and exhaust ports on opposite sides of cylinder at one end), loop-scavenged porting (inlet and exhaust ports on same side of cylinder at one end), through or uniflow scavenged (inlet and exhaust ports or valves at different ends of cylinder)

5. Fuel

Gasoline (or petrol), fuel oil (or diesel fuel), natural gas, liquid petroleum gas, alcohols (methanol, ethanol), hydrogen, dual fuel.

6. Method of mixture preparation 

Carburetion, fuel injection into the intake ports or intake manifold, fuel injection into the engine cylinder.

7. Method of ignition

Spark ignition (in conventional engines where the mixture is uniform and in stratified-charge engines where the mixture is non-uniform), compression ignition (in conventional diesels, as well as ignition in gas engines by pilot injection of fuel oil)

8. Combustion chamber design

Open chamber (many designs: e.g., disc, wedge, hemisphere, bowl-in-piston), divided chamber (small and large auxiliary chambers; many designs: e.g., swirl chambers, prechambers)

9. Method of load control

Throttling of fuel and air flow together so mixture composition is essentially unchanged, control of fuel flow alone, a combination of these.

10. Method of cooling

Water cooled, air cooled, uncooled (other than by natural convection and radiation)