Over time, Wright refined the R-760, using suffix letters to indicate successive versions. The original R-760 (or J-6-7) was rated for 225 hp (168 kW),[2] while the R-760E of 1931 could do 250 hp (186 kW) thanks to an improved cylinder head design.[3][4][5] Wright later added another suffix to show different power levels. The R-760E-1, introduced the same year as the R-760E, had a takeoff power rating of 300 hp (224 kW) thanks to higher-compression pistons and a greater RPM limit.[3][6][7] The even more powerful R-760E-2 of 1935 could reach 350 hp (261 kW) for takeoff due to increased supercharging and an even higher RPM limit.[3][8][9] On the other hand, the R-760E-T, designed for trainer aircraft, had the R-760E-1's high-compression pistons, but the supercharger was removed, thus giving just 235 hp (175 kW).[3][10][11]