ISRO Vikas family of hypergolic liquid-rocket engines used across PSLV and GSLV stages. ISRO’s GSLV Mk II page identifies a newer higher-chamber-pressure Vikas for GS2 with 846 kN nominal thrust and 150 s burn, plus four Vikas-powered L40 liquid strap-ons; exact submodel boundaries remain at the vehicle-configuration layer.