Definition of brake power (BP) Brake power is defined as the mechanical power available where in an internal combustion engine?

Introduction / Context:Several power terms describe engine performance: indicated power (developed in-cylinder), brake power (delivered at the shaft), and friction power (the difference). Correctly distinguishing these terms is essential for testing and analysis.

Given Data / Assumptions:

• Steady operation on a dynamometer.
• Mechanical losses include friction, pumping, and accessory drives.
• Power measured at the output shaft.

Concept / Approach:Indicated power is derived from the pressure-volume work inside the cylinder. Mechanical losses reduce the available output. The net mechanical power at the crankshaft flange is brake power, typically determined by torque and speed measurements on a brake or dynamometer: BP = 2 * pi * N * T (with consistent units).

Step-by-Step Solution:Measure torque at the output shaft using a brake/dyno load cell.Measure rotational speed N.Compute BP from BP = torque * angular speed.Recognize that BP excludes in-engine losses already accounted for by the difference from indicated power.

Verification / Alternative check:Brake specific fuel consumption uses BP as the denominator; test standards explicitly define BP at the engine crankshaft or test rig output coupling.

Why Other Options Are Wrong:Option (a) describes indicated power. Option (c) is not a standard measurement point and still suffers bearing losses; BP is defined at the output. Option (d) contradicts standard definitions.

Common Pitfalls:Confusing indicated and brake power or mixing units when calculating BP from torque and RPM.

Final Answer:At the crankshaft output