A four stroke cycle engine is an internal combustion engine that utilizes four distinct piston strokes (intake, compression, power and exhaust) to complete. The piston makes two complete passes in the cylinder to complete one operating cycle. An operating cycle requires two revolutions (720 °) of the crankshaft. The four stroke cycle engine is the most common type of small engine. A four stroke cycle engine in one operating cycle consists of, including intake, compression, ignition, power, and exhaust strokes.
To release the chemical energy in diesel effectively, an atomized form of the fuel is made to contact with high temperature and high pressure air. A diesel engine usually operates by repeating a cycle of four-stage or strokes combustion principle, also known as the otto cycle. The chemical energy release (combustion) is effectively transferred as mechanical rotational energy. The operation of a diesel engine is all about producing high temperature and high pressure air continuously.
There have been different opinions across industry experts over what makes a good diesel engine. It could probably be due to different requirements that each individual has over the use of their engines. However here are some of the common factors that came up regularly while speaking to industry experts, and most use them to evaluate what makes a good engine.
Efficiency & Power performance are two of the most asked questions when comparing between a diesel and petrol engine. The fundamentals of both engines are similar and the type of fuel burned by either power plant doesn’t change anything in relation to the engine’s general markeup. (e.g. a crankshaft spinning, connecting rods and pistons moving up and down, air being pumped in and exhaust being routed out.) Thus the basic architecture is very much the same. However what goes on in-cylinder in a diesel is vastly different from what you’ll find in its petrol-powered counterpart. The easiest way to explain the difference between petrol and diesel engines is with “air” and “fuel”. In a petrol engine, airflow is everything, you’re throttling air. A diesel mill is the polar opposite. It works on the premise of throttling the amount of fuel being injected – the air simply follows suit.