The aim of this paper is to investigate the effects of the using of low ratio n-butanol/diesel fuel blends on the engine performance and exhaust emissions in a turbocharged automobile diesel engine. Experiments have been performed for different n-butanol/diesel blends, kept at low blending ratios, nB2 (nB2 contains 2% n-butanol and 98% diesel fuel in volume basis), nB4 and nB6, at different engine speeds and loads. The test results showed that engine characteristics and nitrogen oxides (NOx) emission improve for nB2 and nB4 at selected engine speeds and loads. However, they deteriorate for nB6. At the end, nB2 was determined as the most favorite blend for engine characteristics and NOx. Smoke reduces for nB2, nB4 and nB6 at all of the selected engine speeds. n-Butanol/diesel fuel blends provide little effect on the in-cylinder pressure and heat release rate of this engine at selected operating conditions. However, total fuel cost for used n-butanol/diesel fuel blends becomes higher than diesel fuel. (C) 2014 Elsevier Ltd. All rights reserved.