E85 (85% Ethanol + 15% Gasoline), as an alternative fuel has been widely used in spark ignited engines used in light duty vehicles. However, they are rarely used in spark ignited heavy duty engines. In this study, we used E85 in a 5.8 litre, multi cylinder, turbocharged, multi point - port injected, spark ignited heavy duty engine, to analyze the performance capability. As E85 has higher octane rating, the compression ratio was increased to 11.5:1. Experimental investigation of In-cylinder pressure was done and the engine’s ignition timing and injection duration was calibrated to operate the engine below peak firing pressure limits, without knocking. The experimental results showed that exhaust gas recirculation resulted in lower peak firing pressure and rate of heat release.The results of the engine test showed that E85 can be used in heavy duty spark ignited engines. The scope for future work is on addressing the higher BSFC and cold start from subzero temperature levels.