The effect of injector configuration on the combustion and emissions of a compression ignition engine, fuelled on ethanol as the main fuel and dimethyl ether as ignition promoter, were investigated. Baseline constant speed tests were initially performed on diesel fuel using the recommended three-hole configuration. The tests were repeated with the recommended three-hole injector and then with a four-hole injector with ethanol as the main fuel. All other aspects of the engine remained unmodified. The four-hole injector resulted in the combustion of ethanol occurring closer to top dead centre, producing marginally more power and higher fuel conversion efficiency. In the case of the four-hole injector, emissions of both THC and NOX were found to be lower than those produced by the three-hole injector. They were, however, in both cases lower than levels achieved with diesel fuelling. (C) 2009 Elsevier B.V. All rights reserved.