48 ICAMMME 2021 In the present study an experimental work has been conducted to characterize the fish oil biodiesel and their blends with diesel and Pyrogallol antioxidant respectively. Fish oil biodiesel (FHOBD) is blended with diesel to produce FHOBD B20. Further to study the effect of antioxidant addition to FHOBD B20, three blends with varied dosage of pyrogallol are prepared. Accordingly, FHOBD B20 is infused with 1, 2, and 3 grams of pyrogallol antioxidant per liter to produce FHOBD B20PG1, FHOBD B20PG2 and FHOBD B20PG3 respectively. Beyond 3 gm deterioration in the blend homogeneity is observed. For the CRDI engine performance evaluation only FHOBD B20PG3 is considered. Advancing the injection timing to 17 o BTDC resulted into improved CRDI engine performance powered with fish oil biodiesel. Further adding Pyrogallol antioxidant into FHOBD B20 blends higher BTE, lower emissions of smoke, HC and CO emissions were obtained for the CRDI engine respectively. Keywords: Fish oil biodiesel, pyrogallol, antioxidant, CRDI, injection timing. 1.0 Introduction D iesel engines have variety of applications due to their higher BTE and they are rougher than gasoline fuelled engines. In the present scenario the conventional fuels may deplete within a span of 10-15 years, due to larger demand of energy. Due to amplified usage of imported products of petroleum results into foreign exchange growth and put load on the economy of the country. Further, strict environmental guidelines increased the demand for partial or complete replacement of conventional fuels with the usage of biodiesels [1]. Biodiesel prepared from waste fish oil could be the very attractive and less costly alternate fuel for diesel. Fish processing industries produces large amount of fish tissue waste and other by-products. These fish waste and other by-products are either rejected or vended at low cost for compost or animal feeds [2]. A superior way to use these by-products is to transform into biodiesel for the benefit of diesel engines. India had one of the elongated coastal regions in Asia and it had outstanding potential in case of fish and by-products of fish containing fish oil and fish meal. The biodiesel produced from locally available fish oil had ability to provide sustainable supply of energy by using this fuel in diesel engines. Fish oil biodiesel also helpful in cost savings and to reduce the dependency on fossil fuels [3]. Clean combustion and easy manufacturing of fish oil methyl ester could be the potential way to reduce requirements of diesel in India [4]. The oxidation stability in case of various alternative fuels may be affected by the existence of unsaturated fatty acids and presence of unwanted impurities and absence of naturally existing antioxidants in the biodiesel feedstock [5]. Nishant et al. (2020) [6] found that, by infusing 950 ppm of pyrogallol antioxidant the biodiesel obtained from Alexandrian laurel could be gathered over extended time period. Avase et al. (2015) [7] found that, for 50% load the BTE and BSFC for the engine running with waste cooking oil biodiesel blend B20A were found to be 0.12% and 0.0295% higher than diesel. CO 2 and NO 2 emissions for B20A were found to be 3.64% and 0.31% higher, while CO and HC were 16.67% and 2.33% lower compared to diesel. Dwivedi and Sharma (2015) [8] used pyrogallol antioxidant in pongamia biodiesel as per the observation enhancement in the stability characteristics of pongamia biodiesel is reported. The optimized quantity of pyrogallol antioxidant for blend PB20 was 300 ppm. Waweru Effect of injection timing on the performance of CRDI diesel engine fuelled with fish oil biodiesel and its blends doped with pyrogallol antioxidants VINOD R N. R. BANAPURMATH BASAVARAJAPPA Y. H. P. A. HARARI V. S. YALIWAL VARUNKUMAR REDDY N and ARUN KUMAR H Messrs. Vinod R, School of Mechanical Engineering, REVA University, Bangalore 560064, VTU Research Scholar, Belagavi 590018, N. R. Banapurmath, Department of Mechanical Engineering, K.L.E. Institute of Technology, Hubballi 580027, Karnataka and Centre for Material Science, School of Mechanical Engineering, K.L.E. Technological University, Vidyanagar Hubballi 580031, Basavarajappa Y.H., Department of Mechanical Engineering, P.E.S. Institute of Technology and Management, Shimoga 577204, P.A. Harari and V.S. Yaliwal, Department of Mechanical Engineering, SDM College of Engineering and Technology Dharwad, Varunkumar Reddy N and Arun Kumar H, School of Mechanical Engineering, REVA University, Bangalore 560064. E-mail: nrbanapurmath@gmail.com / vinod.r@reva.edu.in