Single overhead cam (SOHC) and double overhead cam (DOHC)

 Single overhead cam (SOHC) and double overhead cam (DOHC)

Single overhead cam (SOHC) and double overhead cam (DOHC) are terms used to describe the arrangement of camshafts in an internal combustion engine.

1. Single Overhead Cam (SOHC):

   • In an SOHC engine, there is only one camshaft located in the cylinder head.
   • This single camshaft is responsible for actuating both the intake and exhaust valves of all cylinders in the engine.
   • The camshaft operates the valves through either rocker arms or directly via tappets (followers).

   SOHC engines are simpler and less expensive to manufacture compared to DOHC engines. They are typically found in many everyday passenger cars and some performance-oriented vehicles.

2. Double Overhead Cam (DOHC):

   • In a DOHC engine, there are two camshafts located in the cylinder head: one for the intake valves and one for the exhaust valves.
   • Each camshaft is specifically dedicated to actuating either the intake or exhaust valves, allowing for more precise control over valve timing and lift.
   • DOHC engines often have more valves per cylinder (usually 4 valves per cylinder), which can improve engine performance and efficiency by allowing better airflow.

   DOHC engines are more complex and generally more expensive to manufacture due to the additional camshaft(s) and associated components. They are commonly found in high-performance vehicles, sports cars, and some luxury cars where engine performance and efficiency are prioritized.

In summary, the main difference lies in the number of camshafts and how they control the valves in the engine. SOHC engines have one camshaft that operates both intake and exhaust valves for all cylinders, while DOHC engines have separate camshafts for intake and exhaust valves, providing potentially better performance at the cost of increased complexity and expense.