Pump boost is the pressure boost given by the pump to the propellants and reactants. The pump boost in typical rocket engines is about sixty atmospheres, the pump boost in the space shuttle main engines is about two hundred atmospheres.

The greater the pump boost, the greater the exhaust velocity; but, pumps are expensive so the pump boost generally ranges between fifty and two hundred atmospheres. Given combustion ratio, exhaust molecular, fuel mass ratio, fuel molecular, oxidizer mass ratio, oxidizer molecular, propellant mass ratio, propellant molecular, propellant usage, pump efficiency, pump need, reactant propellant usage and working temperature pump boost can be calculated which is in turn used to calculate the chamber pressure.

propellant energy = propellant usage * pump efficiency * working temperature * 8,314 J * K / kmol / 0.2

combustion exhaust = combustion ratio / exhaust molecular

uncombustion = 1.0 - combustion ratio

pump energy = propellant energy * propellant mass ratio / propellant molecular + propellant energy * reactant propellant usage * ( fuel mass ratio * ( uncombustion / fuel molecular + combustion exhaust ) + oxidizer mass ratio * ( uncombustion / oxidizer molecular + combustion exhaust ) )

pump boost = pump energy / pump need
 

chamber pressure = injector efficiency * ( pump boost + tank pressure )
 
 

This is used in pumped rocket and rocket cost.
 
  Rocket