Ratios and proportions are always fertile ground for confusion, because there are so many ways to interpret them especially if they are stated as word problems rather than a math formula.
Lets put some numers on this and see what comes out, based on how I am reading this.
Assume:
1300 cc engine displacement, and 6 - 9 psi boost with an assumed VE of about .90. Just to pick an operation point lets say 8000 rpm.
That would give a swept engine volume of about 213 CFM at .90 VE or 192 CFM of air at a manifold absolute pressure of 23.7 psi ( pressure ratio of 1.61) for a true air flow of about 310 CFM or about 21.7 lbs of air/min.
(sorry guys I grew up with imperial units
)
At a 12.5:1 air fuel ratio (by mass) you would need 1.736 lb/min of fuel, if the WI rate is at 22% of fuel,(the max recommedation) then you have 0.38 lb/min of injectant.
Your total "fluids to air ratio" becomes 21.7 : (1.736 + .38) or 10.255:1.
At least that is how I am inerpreting the recommendation from the RBR calculator.
Larry