ABSTRACT The present experimental work describes the performance of a variable compression ratio diesel engine with hibiscus cocos nucifera biodiesel. The Taguchi method is used to optimise engine performance parameters. Compression ratios from 15:1 to 18:1, loads of 6, 9, and 12 kg, and blends B05, B10, B15, B20, B25, and diesel are the input parameters. Brake power, brake thermal efficiency, and mechanical efficiency were chosen as performance parameters. The optimum values are 23.7250% brake thermal efficiency, 3.41667 kW of brake power, and 70.0600% mechanical efficiency with a load of 12 kg, a compression ratio of 16:1, and blend B20. The CO emissions of blend B25 were reduced by 36.36% at a compression ratio of 18:1 when compared to diesel at full load. NOx emissions were increased with an increase in compression ratio and blend ratio. The mass fraction burned is higher for B20 and B25 with an 18:1 compression ratio.