<p>The use of alternative fuels is widely recognized as an effective way to reduce emissions from internal combustion engines. While biodiesel has been widely studied in naturally aspirated engines, limited research addresses its impact on modern turbocharged configurations. To address this gap, the present study compares the performance and emission characteristics of naturally aspirated and turbocharged engines operating with various biodiesel blends produced from waste oil. Results demonstrate that turbocharging, when combined with a B20 biodiesel blend, substantially reduces emissions while maintaining performance levels comparable to conventional diesel. Turbocharging decreased fuel consumption by up to 20% and enhanced brake torque by as much as 75%, while B20 delivered performance nearly identical to petroleum diesel. Moreover, unburned hydrocarbons were reduced by approximately 6% under boosted conditions. These findings contribute to a deeper understanding of biodiesel utilization in advanced engine technologies and support the development of cleaner, more efficient propulsion systems for diverse applications.</p>