HIGH OCTANE UNLEADED AVIATION GASOLINE

An unleaded aviation fuel composition having a MON of at least 99.6, sulfur content of less than 0.05wt%, CHN content of at least 98wt%, less than 2 wt% of oxygen content, an adjusted heat of combustion of at least 43.5 MJ/kg, a vapor pressure in the range of 38 to 49 kPa, comprising a blend comprising: from 5 vol.% to 25 vol.% of toluene having a MON of at least 107; from 0.5 vol.% to 4 vol.% of aniline;from 30 vol% to 70 vol% of at least one alkylate or alkyate blend having an initial boiling range of from 32°C to 60°C and a final boiling range of from 105°C to 140°C, having T40 of less than 99°C, T50 of less than 100°C, T90 of less than 110°C, the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, 3-20vol% of C5 isoparaffins, 3-15vol% of C7 isoparaffins, and 60-90 vol% of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol% of C10+, based on the alkylate or alkylate blend; from 0.1 vol.% to 10 vol.% of branched alkyl acetate; at least 8 vol% of isopentane, isobutane, or mixture thereof in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa; from 2 vol.% to 10 vol.% of mesitylene; wherein the fuel composition contains less than 1 vol% of C8 aromatics. As well as meeting the requirements of the ASTM D910 specification, the unleaded aviation fuel compositions of the present invention exhibit reduced bladder delamination, improved materials compatibility such as reduced elastomer swelling and reduced paint staining, and improved engine endurance.