Four stroke vs six stroke engine

Heat engine converts thermal energy into mechanical energy. There are various types of heat engines based on different criterias. Based on working cycles heat engines are categorized into 2-stroke, 4-stroke and 6-stroke engines.

4-stroke and 6-stroke engines are types of internal combustion (i.c.) engines used to convert fuel into mechanical energy. They differ in the number of strokes or phases in their operating cycles, which are the sequences of events that occur within the engine to produce power. Here's an overview of both types.

4 Stroke Engine

4 stroke engine

In 4-stroke engine, four events take place inside engine cylinder viz. suction, compression, power and exhaust. All these events are completed in four strokes of the piston or in two revolutions of the crank shaft. Hence it is known as four-stroke engine. The four cycles are shown in the figure-1.

• Intake Stroke: The engine takes in a mixture of air and fuel through the intake valve as the piston moves downward.
• Compression Stroke: The piston moves upward, compressing the air-fuel mixture, which increases its pressure and temperature.
• Power Stroke: A spark plug ignites the compressed air-fuel mixture, causing an explosion that forces the piston down. This is the stroke where power is produced.
• Exhaust Stroke: The piston moves back up while the exhaust valve opens, allowing the burned gases to be expelled from the cylinder.

In 2-stroke engine, the whole sequence of events i.e. suction, compression, power and exhaust are completed in two strokes of piston i.e. one revolution of crankshaft.

It's the most common type of internal combustion engine and is widely used in cars, motorcycles, and many other applications.

6 Stroke Engine

6 stroke engine

It is developed by modifying 4-stroke design to improve efficiency and reduce emissions. It is type of internal combustion engine based on 4-stroke engine with additional complexity. There are two power strokes viz. one with fuel and other with steam or air.

The 6-stroke engines are categorized into single piston type and opposed piston type. The single piston uses one piston in the cylinder. Opposed piston design use two pistons per cylinder operating at different rates with detonation occurring between the pistons. Single piston designs include Griffin 6-stroke engine, Bajulaz 6-stroke engine, Crower 6-stroke engine and Velozeta 6-stroke engine etc. Opposed piston designs include Beare head, M4+2 etc. Other two piston designs are also available.

Following are the six stages in 6-stroke engine having four valves viz. suction valve, air inlet valve, exhaust valve and air exhaust valve.
• Suction• Compression• Ignition• Exhaust• Air Suction• Air Exhaust.

The first 4 strokes are same as either Otto or diesel cycle. The energy is produced in power stroke. After the end of 4 strokes, the bore will be still hot which is hot enough to expand water. Hence after the end of fourth stroke, when piston is moving towards BDC (Bottom Dead Center), water is inserted inside the cylinder, the water is expanded by the addition of heat to it. It is considered to be the fifth stroke. This stroke also produces power. Hence in a cycle, power is produced twice. After the fifth stroke, the piston is reciprocated back towards TDC (Top Dead Center), which is considered to be the sixth stroke. The figure-1 depicts the working of 6-stroke engine. As shown water is injected at the end of exhaust, so that an extra power and exhaust stroke is added.

The six stroke engine is still largely experimental and hasn't seen widespread commercial use. It aims to improve efficiency by extracting more energy from the same amount of fuel, potentially reducing emissions and fuel consumption. However, it's more complex and not as commonly used as the four stroke engine.

Difference between 4 stroke and 6 stroke engine

Following table summarizes differences between 4 stroke and 6 stroke engine types with respect to various features.

Features 4 stroke engine 6 stroke engine
Number of cycles 4 cycles, •Suction •Compression •Ignition •Exhaust 6 cycles, •Suction •Compression •Ignition •Exhaust •Air Suction •Air Exhaust.
Number of power strokes One Two
Output torque Lower Higher
Output Power Lower Higher
Efficiency Low High
Emission High Low
Air pollution Higher Lower
Fuel consumption High Low
Cooling System Good Better due to more air intake.
Complexity Simpler design with fewer moving parts More complex with additional moving parts for the extra strokes.
Practical application Widely used in various applications (e.g. cars, bike, motorcycles) Primarily experimental; not widely used in commercial applications
Development stage Mature technology with decades of refinement Experimental concept, limited practical implementation

Conclusion : The 4 stroke engines have four phases (intake, compression, power, exhaust) per cycle, with one power stroke, are widely used in various applications, and are known for their simplicity but may have lower efficiency. In contrast, 6 stroke engines feature an experimental design with six phases (intake, compression, power x2, exhaust x2) per cycle, offering the potential for higher efficiency due to two power strokes, lower emissions, and reduced fuel consumption, but they are more complex and not widely used in practical applications as they are still in the experimental stage.


what is difference between

RF and Wireless Terminologies