How does the engine's temperature affect its performance?

The performance of an engine is intricately tied to its operating temperature, making the influence of temperature on power output and efficiency quite significant. When an engine reaches its optimum operating temperature, the fuel combustion process becomes more efficient. This means that the engine can extract more energy from the fuel, leading to better power output.

Moreover, a properly heated engine allows for optimal air and fuel mixture ratios, enhancing combustion efficiency. If the engine is too cold, it can lead to incomplete combustion, lower power output, and reduced fuel efficiency. Conversely, if the engine is too hot, it may cause knocking or pre-ignition, which can also harm performance.

Additionally, emissions are affected by engine temperature, as running at the correct temperature helps the catalytic converter to operate efficiently, thus reducing harmful emissions. However, the primary focus here is on how temperature affects both the overall power and efficiency of the engine, making the response that it can influence both power output and efficiency the most comprehensive and accurate.