  We compute the evolution of a quasi-spherical, slowly rotating accretion flow
around a black hole, whose mass and spin evolve adequately to the mass-energy
transfer through the horizon. Our model is relevant for the central engine
driving a long gamma ray burst, that originates from the collapse of a massive
star. Our results show how much mass and spin a newly formed black hole should
possess during collapsar to launch long GRB.
