How does an overhead cam (OHC) engine differ from a pushrod engine?

An overhead cam (OHC) engine is characterized by its camshaft being positioned above the engine's cylinders, which allows for more direct control of the intake and exhaust valves. This arrangement reduces the number of moving parts needed to operate the valve system, generally leading to increased efficiency and a more compact design compared to pushrod engines, where the camshaft is located within the engine block.

The elevated position of the camshaft in OHC engines enables the implementation of multiple valves per cylinder, improving airflow and engine performance. Additionally, the design facilitates quicker response times for the valves, which can enhance overall engine efficiency and power output.

In contrast, pushrod engines utilize a more traditional approach where the camshaft is situated in the engine block, necessitating a series of pushrods and rocker arms to transfer motion to the valves. This design can result in more complexity and additional moving parts that contribute to weight and can potentially affect overall engine efficiency.

Understanding the fundamental design differences between these two types of engines highlights why the overhead cam configuration is often preferred for modern engines, promoting innovations in performance and efficiency.