在不同的节气门开度、转速、空气燃料比、点火提前角等运转条件下，对改装的 ４９２ＱＣ天然气发动机和原发动机（燃用汽油）的扭矩、功率、天然气消耗量（或燃油消耗量）、空气消耗量等进行了测量．实验结果表明，当发动机由燃烧汽油时的工作状态直接变换为燃烧天燃气时，发动机的扭矩或功率下降非常大，在最大扭矩点约为燃烧汽油时的１７％；发动机燃用天然气时，与浓混合气条件相比稀混合气条件的扭矩在高速时较大，低速时较小，并且最大扭矩对应的转速较高；增大点火提前角，可使发动机燃烧天然气时的动力性得到改善，但这种改善是有限的． The torque, power, natural gas consumption (or fuel consumption) of the modified 492QC natural gas engine and the original engine (gasoline) under different operation conditions of throttle opening, speed, air-fuel ratio and ignition advance angle, , Air consumption, etc. were measured. The experimental results show that when the engine is directly converted to combustion natural gas by the combustion of gasoline, the engine torque or power loss is very large, about 17% of the maximum torque when burning gasoline; when the engine is burning natural gas, Compared with lean condition, the torque of rich mixture is larger at high speed and smaller at low speed, and the rotation speed corresponding to the maximum torque is higher. Increasing the ignition advance angle can improve the dynamic performance of natural gas combustion engine, However, this improvement is limited.