Effect of fuel composition and ignition timing on combustion parameters of spark ignition (SI) port fuel injection (PFI) engine had been studied experimentally. The engine was fuelled with an ethanol and ethanol-gasoline blend E85. The engine was operated at steady speed at 1,500 min-1 and four load points have been used. Minimal ignition timing advance for maximal brake torque (MBT) at stoichiometric air/ fuel ratio for the tested fuels were found. The fuels were tested at their respective MBT timing and gasoline MBT timing. MBT timing was retarded by 8–11% for ethanol and 5–10% for E85 fuel, comparing to gasoline MBT timing. Indicated mean effective pressure (IMEP) was not affected by ignition timing in tested conditions. Maximal cylinder pressure was increased and flame development phase was extended, when gasoline MBT was used with fuels with high ethanol content at tested conditions. © 2017, Eesti Pollumajandusulikool. All rights reserved.