Validation of Road Load Characteristic of a Sub-Compact Vehicle by Engine Operation

Abstract

Vehicle efficiency relates to pollutants and cost savings in third world countries. In terms of sub-compact cars, the vehicle characteristics are governed by the engine and road load characteristics. The main objective was to evaluate the coefficients of rolling resistance and drag on a moving sub-compact car and to compare the results from engine tests on a dynamometer. Tests were conducted on a local sub-compact car to measure engine speed, throttle position and air fuel ratio while Global Positioning Systems (GPS) recorded data of the vehicle’s speed and position. Also, dynamometer testing was carried out to determine the vehicle characteristics. The results of an on the road roll down test and cruising test were combined to get the road load characteristics of the vehicle. A comparison of the road loads obtained with the actual engine dynamometer test was found to have about 5% error. The experimental errors show the validation of the tests. The tests show the dynamometer’s relation to real life road loads.