Indicated Power Calculator Equation

Indicated Horsepower Equation:

\[ IHP = \frac{P \times L \times A \times N}{33000} \]

Mean Effective Pressure (P):

psi

Stroke (L):

Area (A):

in²

RPM (N):

RPM

Indicated Horsepower (IHP):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Indicated Horsepower Equation?

The Indicated Horsepower (IHP) equation calculates the power developed in the cylinders of an engine. It represents the theoretical power output before accounting for mechanical losses. The formula is derived from the work done during the engine cycle.

2. How Does the Calculator Work?

The calculator uses the IHP equation:

\[ IHP = \frac{P \times L \times A \times N}{33000} \]

Where:

\( P \) — Mean effective pressure (psi)
\( L \) — Length of stroke (ft)
\( A \) — Area of piston (in²)
\( N \) — Number of power strokes per minute (RPM)
33000 — Conversion factor (ft-lb/min to horsepower)

Explanation: The equation multiplies the mean effective pressure by the displacement volume and speed, then converts to horsepower units.

3. Importance of IHP Calculation

Details: Calculating indicated horsepower is essential for engine design, performance analysis, and efficiency calculations. It helps engineers understand the theoretical maximum power an engine can produce.

4. Using the Calculator

Tips: Enter mean effective pressure in psi, stroke length in feet, piston area in square inches, and RPM. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between IHP and BHP?
A: Indicated Horsepower (IHP) is the theoretical power developed in the cylinders, while Brake Horsepower (BHP) is the actual power available at the output shaft after accounting for mechanical losses.

Q2: Why is the conversion factor 33000?
A: 33000 comes from the definition of 1 horsepower, which equals 33000 foot-pounds of work per minute (550 ft-lb/sec × 60 sec/min).

Q3: How is mean effective pressure determined?
A: Mean effective pressure is typically calculated from indicator diagrams or pressure-volume curves that show the pressure variations during the engine cycle.

Q4: Does this equation work for all engine types?
A: The basic principle applies to reciprocating engines, but specific modifications may be needed for different engine configurations (2-stroke vs 4-stroke, etc.).

Q5: What are typical IHP values for engines?
A: IHP values vary widely based on engine size and type, from a few horsepower for small engines to thousands for large industrial or marine engines.