Limited fossil fuel reserves led to focus on alternatives fuels for combustion engines. Several studies reported optimal (20%) biodiesel blend for utility in compression ignition engine at constant compression ratio. Literature lacks on the study of palm-based biodiesel in blended form at varying engine compression ratios. In this study, an initiative was undertaken to study the effect of variable compression ratio (16:1, 17:1 and 18:1) on various engine characteristics by fuelling 20% palm biodiesel blending compression ignition engine. The ignition delay period decreased, whereas the peak cylinder pressure and brake thermal efficiency increased with increase in the engine compression ratio from 16:1 to 18:1. At 3.5 bar bmep, brake thermal efficiency values were observed to be 28.9, 30.8 and 33.8% at 16:1, 17:1 and 18:1 CRs, respectively in B20 fuel. Moreover, increasing compression ratio from 16:1 to 18:1, the average reduction in emissions of hydrocarbon, carbon monoxide and smoke opacity were observed to be 47.8, 41.0 and 35.7%, respectively whereas, oxides of nitrogen emissions increased by 41.1%. Thus, it is inferred that B20 fuel performed well at high engine compression ratio. (C) 2019 Elsevier Ltd. All rights reserved.