The engine power of an excavator is one of the core factors determining its operating efficiency, directly influencing key indicators such as digging speed, load capacity, and continuous operation capability. Specifically, the relationship between engine power and operating efficiency can be analyzed from the following aspects:

I. Core Role of Engine Power

Engine power (usually measured in kilowatts (kW) or horsepower (HP)) is an indicator of the energy output by the engine. The greater the power, the stronger the driving force for the hydraulic system and mechanical structures (such as the boom, arm, and bucket). All movements of the excavator (digging, lifting, rotating, traveling) rely on the engine to drive the hydraulic pump to generate pressure. Therefore, power directly determines the speed, strength, and stability of these movements.

II. Specific Impact on Operating Efficiency

1. Digging Speed and Operation Cycle Time
   A higher power means a higher output flow of the hydraulic pump, resulting in faster movements of the boom, arm, and bucket (e.g., shorter time for bucket penetration, lifting, and unloading).

   The operation cycle ("digging → rotating → unloading → returning") is shortened, increasing the number of operations per unit time. For example, the cycle time of a 20-ton excavator (with a power of approximately 110kW) may be 20%-30% shorter than that of a 10-ton excavator (with a power of approximately 70kW), significantly increasing the daily earthwork volume.

2. Load Capacity and Adaptability to Hard Rock/Heavy Load Conditions
   A high-power engine can provide higher hydraulic system pressure, enabling the bucket to withstand greater digging resistance, making it suitable for excavating hard materials such as hard soil, gravel, and rocks.

   A low-power engine may experience "stalling" (a sudden drop in engine speed) under heavy loads, causing digging interruptions. In contrast, a high-power engine can maintain stable output, avoiding efficiency losses. For example, large mining excavators (with a power of over 500kW) can easily crush hard rocks, while small excavators (≤100kW) have extremely low efficiency in such working conditions.

3. Coordination of Compound Movements
   Excavator operations often require multiple movements to be performed simultaneously (e.g., "boom lifting + arm retracting + rotating"), which requires the engine to drive multiple hydraulic circuits at the same time.

   A high-power engine can ensure sufficient power for all components during compound movements, with no jamming or delay, reducing wasted operation time.

   A low-power engine may suffer from insufficient power distribution during compound movements, resulting in slower movements or "prioritizing one movement" (e.g., reduced lifting speed during rotation), lowering overall efficiency.

 4.Continuous Operation and Adaptability to Harsh Environments
High-power engines typically have stronger heat dissipation systems, making them less likely to shut down due to overheating in harsh environments such as high temperatures and high altitudes, ensuring continuous operation.

Low-power engines are prone to overheating during high-load, long-term operations and require frequent shutdowns for cooling, indirectly reducing efficiency.

III. "Non-linear Relationship" Between Power and Efficiency

It should be noted that the relationship between engine power and operating efficiency is not a simple proportional one; there is a "diminishing marginal benefit":

When the power is increased to match the design limit of the model (e.g., a 20-ton model with 120kW vs. 140kW), the efficiency improvement may only be 5%-10% (limited by other factors such as the hydraulic system and structural strength).

Blindly pursuing high power will lead to a surge in fuel consumption (a 30% increase in power may result in a 40% or more increase in fuel consumption), which instead increases operating costs. Therefore, it is necessary to select a model with "power adaptation" according to the working conditions (e.g., earthwork operations do not require top-level power, while hard rock operations need high power for support).

IV. Comparison of Practical Cases

Conclusion: Engine power directly determines the operating efficiency of an excavator by affecting movement speed, load capacity, coordination of compound movements, and continuous operation capability. However, it is necessary to select the appropriate power based on specific working conditions (material hardness, operation intensity) to avoid cost waste caused by "excessive power".