Question

The ratio of the indicated thermal efficiency to the air standard efficiency is known as ______________

(a) mechanical efficiency

(b) overall efficiency

(c) relative efficiency

(d) volumetric efficiency

The question was asked during an interview.

Asked question is from Engine Efficiencies in portion Measurements and Testing/Performance Parameters and Characteristics of IC Engine

Answer 1

The correct answer is:

(c) relative efficiency

Relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency. It indicates how well the actual engine performs compared to the theoretical maximum efficiency based on ideal thermodynamic cycles (like the Otto or Diesel cycle). This measure helps assess the real-world performance of an engine in relation to its theoretical potential.