AbstractAn experimental investigation and Taguchi optimization analysis were carried out to optimize Jatropha biodiesel engine parameters for lower fuel consumption and exhaust emissions. The engine parameters considered for optimization were injection timing, injector opening pressure, nozzle configuration, nozzle tip protrusion, percentage of exhaust gas recirculation, fuel type, brake mean effective pressure (BMEP), and speed. Taguchi’s signal-to-noise ratio approach was applied to obtain an optimal level setting of these parameters. From the experimental results and further analysis it is concluded that under 95% confidence interval a nozzle configuration of 5×0.18, tip protrusion of 3.5 mm, exhaust gas recirculation of 0%, BMEP of 3.2 bar, and speed of 1,800 rpm with Jatropha biodiesel fuel gave the minimum carbon monoxide (CO) and unburned hydrocarbon (HC) emissions, whereas the lowest nitric oxide (NO) emissions were obtained with an injection timing of 350 crank angle degrees (CAD), nozzle configu...