AbstractThe manuscript addressed experimental work related to microalgae‐based biodiesel blend B20, that is, 20% algae biodiesel and 80% diesel, as an alternative fuel as a possible source to power diesel engines. The physiochemical characteristics of this B20 blend were almost in line with diesel fuel as per American Society for Testing and Material standards. Coupled experimentation related to variations in compression ratio (CR) 17, 19, and 21 and fuel injection timing (IT) of 21°, 23°, and 25° before top dead center (bTDC) with load variations noted on diesel engines. We observed that, at full load, CR21 and 23° bTDC fuel IT, the brake thermal efficiency parameters rose significantly, whereas brake‐specific fuel consumption, and combusted flue gas temperatures also plummeted. The CO, HC, and smoke opacity emission for the B20 blend at CR21 and FIT23 has decreased by 30.52%, 33.33%, and 32.96%, respectively. At full load conditions, NOx emission for B20 biodiesel at CR21 was increased compared with the standard setting and compared with diesel it was increased by 6.46%.