Abstract: A motor assisted turbocharger comprised of a compressor rotor and a motor drive on separate aligned bearing axes, and a torque transmitting slip coupling therebetween devoid of mechanical interengagement and driving the compressor on demand, and an engine exhaust driven turbine rotor coupled to the compressor rotor with an averrunning clutch which separates the compressor mass from the turbine mass for maximized acceleration of the compressor rotor and turbine rotor by disengagemnt of the turbine rotor from the compressor rotor, and with an inertia responsive mechanism to engage and disengage said torque transmitting slip coupling.