What does OHC stand for when discussing a type of engine?

OHC stands for Overhead Cam, which refers to a design feature in an engine where the camshaft is located above the cylinder head. This architecture allows for a more direct connection between the camshaft and the valves, which can result in more precise timing and better performance compared to overhead valve (OHV) designs or other configurations.

In an overhead cam engine, the placement of the camshaft contributes to improved airflow, efficiency, and therefore, power output. This setup can also reduce the number of moving parts needed for valve operation, which can lead to lighter engine designs and increased reliability.

The other options do not accurately define OHC in the context of engine types. "Outer crankcase" and "open circuit" do not pertain to engine mechanics, while "operational combustion" lacks a specific meaning directly relating to engine design or performance. Understanding OHC is crucial for comprehending modern engine design and how they can impact performance and efficiency in small engines.