DIFFERENCE BETWEEN TWO-STROKE AND FOUR-STROKE CYCLE DIESEL ENGINES

TWO-STROKE CYCLE DIESEL ENGINE DIAGRAM

FOUR-STROKE CYCLE DIESEL ENGINE DIAGRAM

DIFFERENCE BETWEEN TWO-STROKE AND FOUR-STROKE CYCLE DIESEL ENGINES

A brief but critical comparison of the merits and limitations of the two-stroke-cycle diesel engine compared with the four-stroke power unit is made below.

• Theoretically, almost twice the power can be developed with a two-stroke engine compared with a four-stroke engine.
• A comparison between a typical 12 lt four-stroke engine and a 7 liter two-stroke engine having the same speed range would show that they would develop similar torque and power ratings. The ratio of engine capacities for equivalent performance for these four-stroke and two-stroke engines would be 1.7:1.
• In a four-stroke engine, the same parts generate power and empty and fill the cylinders. With the two-stroke engine, the emptying and filling can be carried out by light rotary components.
• With a two-stroke engine, 40–50% more air consumption is necessary for the same power output; therefore the air-pumping work done will be proportionally greater.
• About 10–20% of the upward stroke of a two-stroke engine must be sacrificed to emptying and filling the cylinder.
• The time available for emptying and filling a cylinder is considerably less in a two-stroke-cycle engine something like 33% of the completed cycle as compared to 50% in a four-stroke engine. Therefore more power will be needed to force a greater mass of air into the cylinder in a shorter time.
• Compared with a two-stroke engine, more power is needed by the piston for emptying and filling the cylinder in a four-stroke engine, due to pumping and friction losses at low speeds. At higher engine speeds the situation is reversed, and the two- stroke’s Roots blower will consume proportionally more engine power – this could be up to 15% of the developed power at maximum speed.
• With reduced engine load for a given speed, a two- stroke engine blower will consume proportionally more of the power developed by the engine.
• A two-stroke engine runs smoother and relatively quietly, due to the absence of reversals of loading on bearings as compared with a four-stroke engine.

RELATED TOPICS

• DIFFERENCE BETWEEN TWO-STROKE AND FOUR-STROKE CYCLE PETROL ENGINES
• WHAT ARE THE PRINCIPAL PARTS OF AN I.C. ENGINE?

• AUTOMOBILE ENGINEERING PROJECTS REPORTS, TOPIC, IDEAS: Get Automobile Engineering projects topics and ideas for study and research. we provide the widest list of Automobile engineering project reports to help students, researchers, & engineers in their RD.

Reference: AUTOMOTIVE ENGINEERING BY DAVID A. CROLLA