Two-stroke diesel engine compared with the four-stroke diesel engine has the following advantages: 

(1) to improve the ability to the work of diesel engine for two cylinder diameter the same diesel engine, the piston stroke and speed, two-stroke diesel engine power should be larger than four stroke times seems to be.
But in fact, as a result of two-stroke diesel engine cylinder with open port and make the working volume has decreased, mechanical transmission of scavenging pump USES certain factors such as power, two-stroke diesel engine power can only increase 60 ~ 80%.
Obviously, if the power is the same, the two stroke diesel engines are smaller and lighter.

 (2) to improve the power performance of diesel engine because every turn 360 ° two-stroke diesel engine crankshaft, of each and every turn 720 ° four-stroke diesel engine one of each, and two stroke diesel engines than four-stroke diesel engine rotation even, can use small flywheel.
 (3) simplify the structure of the diesel engine and save the inlet valve and its transmission device.
For some two-stroke diesel engines, the exhaust valve and its transmission are omitted.
Therefore, its maintenance is simple and convenient.
Two stroke diesel engines have more advantages, but it also has its inherent drawbacks: 

(1) poor quality of ventilation, thermal efficiency is low because the two stroke diesel engines for air with a much shorter time than a four-stroke diesel engine, and sweep and exhaust almost simultaneously, so the fresh air and exhaust gas permeability in the process of scavenging mix serious, some fresh air with exhaust gas discharge, increased the air consumption, theIn order to reduce the gas quality, the fuel combustion is affected, the thermal energy is not sufficient, and the thermal efficiency is lower than that of the four-stroke diesel engine.

 (2) the higher heat load in the speed phase at the same time, two stroke machine per unit time of burning in the cylinder number is double that of four-stroke machine, therefore, two stroke machine with high temperature gas in the cylinder in contact parts heat load is higher.
The above disadvantages of two-stroke diesel engine will become more serious with the increase of rotational speed.
Therefore, large and low speed diesel engines use two strokes;
Small high-speed diesel engines use four strokes;
Medium speed machine, four stroke and two stroke are adopted, but mainly four stroke machine.
The comparison between two stroke diesel engines and four stroke diesel engines has the following characteristics in addition to the above advantages and disadvantages: 

(1) the camshaft speed of the two-stroke diesel engine is the same as that of the crankshaft;
And four stroke diesel engine camshaft speed is half of crankshaft speed, that is, 1:2.
(2) a work cycle, two-stroke diesel engine, work is downward external uplink is driven by external force, and four stroke machine except burning expansion stroke foreign work, three other stroke are consumption power strokes.

(3) the two-stroke diesel engine exhaust overlap Angle is about 80 ~ 80 ° CA, four-stroke diesel engine valve overlap Angle is small, about 25 ~ 60 ° CA.