A method of operating a hybrid powertrain having an internal combustion engine monitors a throttle intake pressure and calculates a first torque capacity from a pressure model using the throttle intake pressure as an input. The method determines a maximum expected air mass from the monitored throttle intake pressure and calculates a second torque capacity from an air mass model using the maximum expected air mass volume as an input. The method calculates a final torque capacity as a function of the first torque capacity and the second torque capacity, and sends the final torque capacity to the hybrid control processor. An engine control module receives a torque request calculated as a function of the final torque capacity. A manifold pressure request is calculated as a function of the torque request, and a throttle is actuated as a function of the manifold pressure request.