The automotive sector has come a long way since the start, and combustion engines have been an important part of this evolution. Most of you familiar with combustion engines must be aware that they come in either two-stroke or four-stroke engines.
While you must have heard at least one of these terms before understanding the difference between these engines, it is important. While these engines do share many similarities, there remain some notable differences between 2-stroke and 4-stroke engines.
In this blog, we will look at these differences and help you choose between 2-stroke and 4-stroke engines. So, let’s get started!
Understanding Combustion Engines
Even the best car mechanic Adelaide won’t be able to explain the difference between you-stroke and four-stroke engines unless you understand how these engines work. Each of these engines has something known as its combustion cycle. This cycle is the up-and-down movement of the piston within the cylinder.
When the piston is nearer to the valves, it will be considered at the top dead centre (TDC) position. On the other hand, when the piston is furthest from the valve, the position is called bottom dead centre (BDC).
As your car’s piston moves from one of these positions to the other and vice versa, it completes a combustion cycle or revolution. This is the process where the engine will suck fuel and air into the piston, ignite it with the spark plug, and naturally expel gas from the exhaust.
Now, let’s understand the process in a sequential manner:
- Intake: Everything starts with the piston moving down the cylinder, allowing air and fuel to enter the combustion chamber.
- Compression: This is when the piston will move back up and automatically close the intake valve for proper gas compression within.
- Combustion: This is where the magic happens with the spark from the spark plug igniting the gas.
- Exhaust: This is the final stage, where the piston backs up the cylinder and opens the exhaust valve.
Difference Between 2-Stroke and 4-Stroke Engines
The crux of the 2-stroke and 4-stroke engine difference is how long it takes to complete a single combustion cycle, which we discussed earlier. This means the number of times the piston moves up and down to complete a single combustion cycle.
What is a 2-stroke Engine?
Every combustion engine where a combustion cycle only needs one piston stroke is called a 2-stroke engine. This means a single stroke of the piston will start compression and trigger the explosion of the compressed fuel.
When the piston makes its return stroke, it opens the exhaust valve to let air out and make way for fresh fuel mixture into the cylinder. The spark plug will then spring into action and fire every single revolution to produce power once every two-stroke of the engine. With these engines, people will pre-mix the oil with the fuel beforehand.
What is a 4-stroke Engine?
In the case of a 4-stroke engine, the piston is designed to complete two strokes during each revolution. The process starts with the compression stroke and one exhaust stroke, with a following return stroke.
This is where the spark plug comes into the picture to fire only once every revolution. This allows the engine to produce power with every four piston strokes. The catch is that 4-stroke engines have a separate oil compartment; you do not need to pre-mix the fuel.
Differences in 2-Stroke Vs 4-Stroke Engines
| Four-Stroke Engine |
Two-Stroke Engine |
| Four-stroke engines do not burn oil and recycle it back into the engine. |
Two-stroke engines require you to pre-mix oil with the fuel beforehand. |
| You can lubricate these engines by oil in an oil sump. |
You cannot lubricate these engines with oil in the oil sump. |
| These engines have valve-train, cams, timing gears, and even pushrods. |
These engines do not have any of that. |
| 4-stroke engines have a relatively complex design but are better for the environment. |
2-stroke engines are smaller in terms of size and design. |
| A four-stroke engine completes two crankshaft revolutions during one combustion cycle. |
Two-stroke engines complete one crankshaft revolution for one combustion cycle. |
| These engines produce relatively lower torque. |
These engines offer better torque. |
| Higher thermal efficiency |
Lower thermal efficiency |
| Leverages the valve for the inlet of the mixture to air and fuel while the outlet for the exhaust. |
This engine uses a port for the inlet of the fuel mixture and an outlet for the exhaust. |
| Relatively expensive since manufacturing is complex and intricate. |
Relatively affordable since the manufacturing process is quite simple. |
| Complicated water-cooling systems increase the cost and complexity of maintenance. |
Simple cooling system making maintenance much easier. |
Which is Better, a 2-stroke or a 4-stroke for Cars?
With a better grip on the 2-stroke vs 4-stroke debate, it is finally time to reach a feasible conclusion as to which is better. But before you get excited, let’s clarify that there is no perfect conclusion. The type of engine that would be the best for you depends on a wide range of factors, including your preferences.
Since both 2 and 4-stroke engines have advantages and disadvantages, you must consider some considerations to reach a feasible conclusion here. So, let’s check out some of the considerations for choosing between a 2-stroke and 4-stroke engine:
1. Emissions and Fuel Efficiency: As fuel prices continue to rise and emissions become a major concern, these are the first things you must consider. Most of the experts in mobile mechanics Adelaide will recommend a 4-stroke engine for better fuel efficiency with lower emissions.
2. Performance and Weight: The weight of your car naturally affects the overall performance potential of the engine. On this front, it is a two-stroke engine that ticks all the right boxes with lighter weight and better performance.
3. Torque: Another important 2 and 4-stroke difference is torque, with the 2-stroke one offering better torque. However, 4-stroke engines are not far behind in this race, especially when performing at lower RPM levels.
4. Vibration and Noise: Whenever you do the two-stroke vs four-stroke comparison, never forget the noise and vibration. In most cases, you will find four-strokes smoother and quieter than the alternative.
5. Durability: Durability is a major factor when choosing between these two engines. Most of the reliable mechanics in Adelaide recommend 4-stroke for better durability and an extended lifespan.
6. Maintenance: You cannot choose between two engines without understanding, which requires more maintenance from a mechanic at the doorstep. Unsurprisingly, the two-stroke engine requires more regular maintenance compared to alternatives.
Also read: Top Tips on How to Increase Diesel Engine Efficiency
Wrapping Up
The auto industry is already on the way to another revolution, with hybrid and electric cars taking centre stage. But this is no reason to be sad for enthusiasts who prefer manual cars that rev like a beast. Down the line, even these cars will improve, and your mobile mechanic can help you choose between a 4-stroke and 2-stroke engine.
You must remember that two- and four-stroke engines have served us well for about a century. So, when it comes to choosing between them, make sure to count your blessings and that you still get to make this choice despite the growing popularity of EVs. If you need assistance with your combustion engine, reach us, and we will send our expert car mechanic at your doorstep.
