1. Open Combustion Chamber:
- Also known as a "cup-in-head" design.
- The combustion chamber is formed by a depression in the cylinder head, with the spark plug located centrally.
- The piston crown has a flat or slightly concave shape.
- The main advantage of this design is its simplicity and ease of manufacturing.
- However, it exhibits lower thermal efficiency compared to other types of combustion chambers.
2. Hemispherical Combustion Chamber:
- The combustion chamber has a hemispherical shape, often used in high-performance engines.
- The piston crown is also hemispherical, matching the shape of the chamber.
- The spark plug is centrally located at the center of the dome.
- This design provides good air-fuel mixing and efficient flame propagation, resulting in improved combustion and thermal efficiency.
- However, it is more complex to manufacture and requires precise cylinder head design.
3. Pentroof Combustion Chamber:
- Also known as the "wedge" or "bathtub" design.
- It combines features of both the open and hemispherical combustion chambers.
- The piston crown has a flat or slightly convex shape, while the chamber is shaped like a truncated cone or wedge.
- The spark plug is located off-center, close to the edge of the combustion chamber.
- This design provides good air-fuel mixing and flame propagation, and allows for efficient combustion.
- It offers a compromise between manufacturing simplicity and thermal efficiency compared to other designs.
The choice of combustion chamber design in SI engines depends on various factors, including performance requirements, fuel efficiency, manufacturing costs, and engine packaging constraints.
