I think where the lbf measurements came from were different sources From the Pratt  Whitney F article I can already see that the stats come to  kN for the engine while the High Performance engine the General ElectricRollsRoyce F is also  kN for the entire system There is a minor change in lbf but I am not sure these are accurate I dont know why the secondary engine is labelled High Performance anyway if I cant find credible sources then I will remove this   Yes I know Im not signed in but I am Theexile