Effects of Gasoline Octane Number on Fuel Consumption and Emissions in Two Vehicles Equipped with GDI and PFI Spark-Ignition Engine

Abstract

The fuel octane number affects the fuel consumption and emission characteristics of vehicles powered by spark-ignition engines. An investigation on the effects of commercial types of gasoline with different research octane numbers (RON) on a vehicle’s performance can provide valuable insights and guidelines for the further improvement of the engine and fuel design. In this work, three commercial-types of gasoline with RON values of 92, 95, and 98 were tested in two compact passenger vehicles. One vehicle is equipped with a gasoline direct injection (GDI) engine with a 1.4-L displacement and a turbocharging system, and the other one is equipped with a port fuel injection (PFI) naturally-aspired engine with a 1.6-L displacement. The new European drive cycle (NEDC) was used to test the effects of three gasoline fuels on both vehicles. The experimental results show that for the vehicle equipped with the GDI engine, with the increase of the RON number, the fuel consumption, carbon dioxide (CO2), and carbon monoxide (CO) emissions increase first and then decrease. The total hydrocarbon (THC) and particulate matter (PM) emissions decrease first and then increase, while the NOx emissions increase gradually; the differences between the maximum and minimum values in the fuel consumptions and the emissions of NOx, CO, THC, CO2, and PM are 0.1 L/100 km (1.7%), 57.54 mg/km (4.5%), 119.26 mg/km (3.3%), 21.73 mg/km (2.3%), 2.55 g/km (2.0%), and 0.24 mg/km (20.6%), respectively. For the vehicle with the PFI engine, with the increase of the RON number, the fuel consumption decreases, the CO2 and THC emissions decrease first and then increase, and the CO emission increases first and then decreases, while the NOx and PM emissions increase gradually; the differences between the maximum and minimum values of the fuel consumptions and the emissions of NOx, CO, THC, CO2, and PM are 0.18 L/100 km, 18.19 mg/km (1.1%), 84.82 mg/km (1.6%), 21.06 mg/km (3.1%), 1.36 g/km (0.9%), and 0.47 mg/km (50.9%), respectively. It can be seen that different RONs lead to the variation in fuel consumption and emissions in an NEDC test. In terms of acceleration performance, the impact of different fuels is considered to be only marginal because the variation in the acceleration time due to fuel effects is less than 2%.