Effects of atmospheric temperature and pressure on the performance of a vehicle

This paper describes the influence of the atmospheric conditions on the performance of a vehicle. Tests were carried out on the road, under different conditions of ambient temperature, pressure and humidity, measuring the acceleration time. The tested vehicle featured a gasoline-fuelled four-cylinder engine, with variable intake manifold length and multipoint fuel injection. The vehicle was tested at sea level and at an altitude of 827 m above sea level, with the ambient temperature ranging from 20 to 30 degreesC. The times required for the vehicle to go from 80 to 120 km/h, from 40 to 100 km/h and to reach distances of 400 and 1000 m leaving from an initial speed of 40 km/h at full acceleration were recorded. The results showed the vehicle performance to be more affected by changes in the atmospheric pressure than in the temperature. An average difference of 3 per cent in the time to reach 1000 m, leaving from the speed of 40 km/h at full acceleration, was found between the atmospheric pressures tested, for a fixed temperature.