A method of operating an engine assembly receiving fuel, including admitting atmospheric air at a temperature T1 through an inlet of a compressor having a pressure ratio of PRGT, compressing the air in the compressor, cooling the compressed air from the compressor through an intercooler to cool the air from a temperature TBIC to a temperature TAIC, delivering the cooled compressed air from the intercooler to an inlet of an intermittent internal combustion engine having an effective volumetric compression ratio rVC, and further compressing the air in the intermittent internal combustion engine before igniting the fuel, where ( PR GT ) a ⁢ ( r VC ) b ⁢ ( T AIC T BIC ) ⁢ ( T 1 T A )