How to use 2D look up table when input has changing dimention?

Hello All,

I am trying to estimate the fuel consumption of an engine by using a look-up table. I have a fuel consumption map which X axes is speed and Y axes is the power. Since engine speed and power is changing at each step, how can I define Breakpoints 1 and two in block parameter?

Please pay attention that here for illustration purpose speed (rpm1) and power(p1) are called from workspace but in my model, they will come directly from an engine model.

Thanks, Babak