This document summarizes the testing and performance of diesel and petrol engines. It describes the key components and operating principles of diesel and petrol engines. It then discusses various performance characteristics of internal combustion engines that are used to evaluate engine performance, such as brake thermal efficiency, indicated thermal efficiency, specific fuel consumption, mechanical efficiency, volumetric efficiency, air fuel ratio, and mean effective pressure. The performance of engines is tested by measuring fuel consumption, brake power, and specific power output using various types of dynamometers.