Glushko exotic N2O4/Pentaborane rocket engine. In 1962-1970 Glushko studied use of Pentaborane 'zip' propellants in his monster RD-270 engine. Created immense toxicity problems but increased specific impulse of the engine by 42 seconds.
AKA: 8D420M. Status: Study 1962-1970. Date: 1962-70. Thrust: 7,159.00 kN (1,609,407 lbf). Specific impulse: 365 s. Specific impulse sea level: 340 s.