  The Collapsar model, in which a massive star (greater than 20 solar masses)
fails to produce a SN and forms a BH, provides the main framework for
understanding long Gamma-Ray Bursts (GRB) and the accompanying hypernovae (HN).
However, single massive-star models that explain the population of pulsars,
predict cores that rotate too slowly to produce GRBs/HNe. We present a model of
binary evolution that allows the formation of Kerr black holes (BH) where the
spin of the BH can be estimated from the pre-collapse orbit, and use the
Blandford-Znajek (BZ) mechanism to estimate the available energy for a GRB/HN.
A population synthesis study shows that this model can account for both, the
long GRB and the subluminous GRB populations.
