China's J-11B jets are equipped with indigenous Chinese WS-10A engines. The Chinese WS-10A silver engine nozzle is very different from the Russian AL-31F black nozzle. In the video below, the Chinese J-11B with WS-10A engines flies around with NO SMOKE exhaust. The Chinese WS-10A engine has complete combustion. All of the jet fuel is converted into thrust. There is no smoke. In contrast, Russian jet engines are smoky, because of incomplete combustion.