Torque and power control in a powertrain

A method of controlling the input power to a transmission in a powertrain having an engine with a power output comprised of engine speed and engine torque, said method comprising the steps of:

• determining a first engine torque limit in accordance with a given transmission input torque limit;
• determining a second engine torque limit in accordance with a given transmission turbine torque limit;
• determining a third engine torque limit in accordance with a given limit of torque converter slip;
• controlling the output of the engine within an envelope of engine speed and engine torque defined by first line exhibiting a constant engine torque equal to the first engine torque limit determination and extending from zero engine speed, a second line extending from an engine peak torque point on said first line to a first point established by said second engine torque limit determination, and a third line extending from said first point to a second point established by said third engine torque limit determination.