What is the engine load rate?
2 Answers
Load rate is a relative percentage concept of torque at a specific engine speed. Its strict definition refers to the ratio of the torque produced at partial throttle opening to the maximum torque produced at wide-open throttle under the same engine speed. Extended information about engine load rate is as follows: 1. When the engine experiences low cylinder pressure: The intake air volume at idle will be higher than normal, the fuel injection volume will also increase accordingly, and the engine load data will rise. When poor engine ignition causes a decrease in engine power, the ECU will compensate by increasing the intake air volume, at which point the engine load data will also show an increasing trend. 2. When there is a vacuum leak downstream of the throttle: It can also lead to an increase in engine load, even though the actual engine load hasn't changed. During vehicle operation, if the power transmission system encounters increased resistance, the additional load will also cause the engine load to rise. For example, when an automatic transmission vehicle experiences a fault with internal stator slippage in the torque converter, since the stator's torque multiplication effect cannot function normally, it will invisibly increase the engine's load, resulting in higher engine load.
Engine load rate refers to the proportion of the engine's actual output power to its maximum possible power, simply put, how hard it's working. For example, when you floor the accelerator to climb a hill, the load rate might soar above 80%, with the engine nearly at full capacity; whereas during steady cruising on flat roads, it's around 40%, relatively relaxed. I often remind friends that this directly impacts fuel efficiency and engine longevity. Too high a load rate, say consistently above 90%, increases wear, leading to overheating or noise; too low, like below 30% in stop-and-go city traffic, wastes fuel and worsens emissions. It's typically measured via sensors that read RPM and torque for calculation, and daily driving can monitor it in real-time with OBD tools. Properly managing the load rate can extend engine durability—I recommend using cruise control on highways to maintain moderate loads.
