A comprehensive ignition delay time database of 3.1 million points using detailed chemistry is generated. The database includes ignition delay times for pure methane, ethane, propane and hydrogen, as well as for gas blends comprising of the mentioned gases. The database covers a broad range of gas engine applications; pressure 1-20 MPa, temperature 900-2500 K, air-fuel equivalence ratio (lambda) 0.9-2.5 and exhaust gas recirculation (EGR) 0-30 m%. For gas blends up to 60 vol% to methane, it is observed that different gas blends with the same HC-ratios/methane-numbers, show similar ignition delay times. Ignition delay time correlations for pure CH4, C2H6, C3H8, H-2 and the gas blends are suggested with mean deviation being as low as about 7%. A new blending methodology is developed to describe the C1-C3 alkanes/H-2 blends at elevated pressure and temperature conditions. Correlations describing the effect of EGR on the ignition delay time are further developed.