How to calculate power of Main Engine (2 stroke engine)?

Calculations

Area of the indicator diagram = a [mm²]
Average height of the diagram = a [mm²] / l [mm]
Average mean indicator pressure = a [mm²] / l [mm] x k [bar / mm]

or P_m = ( a / l ) x k [bar]

where k = spring scale in bar per mm

Work done in one cycle = Mean Indicated Pressure x Area of the Piston x Length of stroke = [P_m] x [A] x [L]

To obtain the power of this unit, it is necessary to determine the rate at which work is done,
i.e. multiply work by number of power strokes in one second.

Now, Indicated Power of Unit [i_p] = Mean Indicated Pressure [P_m] x Area of Piston [A] x Length of Stroke [L] x Number of Power Strokes per Second [N]