In this article, an investigational analysis has been conducted to explore the effect of biodiesel fuel blends on characteristics of engine and releases (CO2, CO, HCl, and NOx) of single-cylinder, four strokes at the variable biodiesel concentration. The releases of gases and the engine's characteristics were measured at six blending biofuels and six-speed conditions and constant load. The blending proportions of biodiesel with diesel fuel-based by volume were at 0% pure diesel, 5%, 10%, 15%, 20%, and 25%. This investigation aims to assess the biodiesel fuel mixture's impact on the CI engine performance in terms of its Bsfc, Ƞbth, and engine release of CO2, CO, HCl, and NOx. The investigation revealed that biodiesel remarkably minimized the release of CO2, CO, HCl, and NOx. The influence of this fuel mixture was studied between 5% to25% biodiesel concentration, and the results of this investigation could aid in understanding the Impact of utilizing biodiesel as an energy source on engine releases and performances.