What indicated power is
Indicated power is the power developed inside the cylinders, calculated from the indicator diagram. Shaft power is lower because of friction. The old imperial formula is IHP = PLAN / 33,000. This page uses SI units and returns kilowatts.
How this calculator works
Area = π/4 × bore². Indicated power (kW) = MIP (bar) × Area (m²) × Stroke (m) × RPM × cylinders × 100 / 6. That is the same as force × stroke × revolutions per second × number of cylinders. For a two-stroke main engine use the engine RPM as given. For a four-stroke engine the number of working cycles is RPM / 2 — this tool assumes one working cycle per revolution (typical two-stroke main engine). Mechanical efficiency is not included.
Who should use it
Useful for engineers checking an indicator card. Compare with the shop-test figures in the engine manual.