Preliminary Assessment of the Emissions-reduction Potential at Unchanged Performance of a Second-generation Biofuel in Historic Engines

The document reports an experimental investigation into the performance and emission characteristics of a second-generation biofuel when applied to a historic spark-ignition engine. The study addresses the challenge of reducing the environmental impact of vintage vehicles, which represent a significant share of the aging European vehicle fleet and typically lack modern emission-control technologies. Conventional RON 95 gasoline is compared with Coryton SUSTAIN Classic Super 80, a low-ethanol biofuel specifically formulated for compatibility with historic engines. Experimental tests were conducted on an air-cooled, four-stroke, two-cylinder Fiat 500 engine mounted on an eddy-current dynamometer. Two testing campaigns were performed: a complete speed sweep from 1000 to 5000 RPM using a fixed carburetor main jet, and a series of steady-state tests at maximum torque and maximum power using four different main jet sizes. Key measured parameters included torque, power, indicated mean effective pressure, fuel consumption, brake specific fuel consumption, air–fuel ratio (lambda), and exhaust emissions of carbon monoxide (CO) and nitrogen oxides (NOx). The results show that engine torque and power obtained with the biofuel closely match those achieved with conventional gasoline across the entire operating range, indicating no appreciable performance penalty. Fuel consumption and BSFC exhibit modest differences, largely attributable to the lower heating value of the biofuel. A significant reduction in CO emissions is observed with the biofuel, while NOx emissions increase, consistent with slightly leaner combustion conditions and higher combustion temperatures. The study concludes that second-generation biofuels such as SUSTAIN Classic Super 80 can be effectively used in historic engines without mechanical modifications, offering a practical pathway to reduce the emissions impact of legacy vehicle fleets within current European decarbonization strategies.