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2 Stroke vs. 4 Stroke: Which One Is Best for You?


When to choose a two-stroke or four-stroke engine.

Gasoline-powered combustion engines produce energy that powers a machine. These machines use either a 2-stroke or 4-stroke engine design application, two similar but different engines. The 2-stroke is mostly used in small appliances, while the 4-stroke is used in bigger machines, including vehicles. 

Two-stroke engines are generally more powerful and cost less. However, four-stroke engines have less repair issues. For power needs where a high RPM is essential, 2-strokes offer the best option. For consistent, steady work performance, a 4-stroke engine is usually the best choice.

This article explores what the 2-stroke and 4-stroke engines are, how they work, and each engine’s pros to help you choose which of them is the most efficient. Read on to find out which engine is the best for you. 

2-Stroke Engine

The 2-stroke engine powers most small appliances such as blowers, scooters, mopeds, remote-controlled cars, boat motors, and chainsaws. The engine has unique features that influence how they function. 

2-cycle engines are lightweight engines that perform only two-piston strikes to complete a combustion cycle. As compared to 4-stroke engines, they weigh up to 50% lower. 

A combustion cycle involves at least four steps: 

  • The intake where air and fuel enter the engines, 
  • Compression where the fuel and air become a mixture, 
  • The power stroke where a spark is ignited to begin the burning process
  • The exhaust stroke where the gasses are released

These engines perform all these functions simultaneously in one crankshaft revolution. It takes them two strokes to complete the combustion cycle. Stroke is the number of times the piston shifts from the bottom dead center, BDC, to the top dead center, TDC, or the other way round (source). The main difference between these two engines is the number of strokes.

The 2-stroke engine runs on a mixture of oil and fuel in one compartment to make its performance a success. However, the engine doesn’t burn all of the oil, releasing some of it alongside the exhaust gasses. That’s the main reason why these appliances tend to have a lot of emissions and smoke.

Also, there isn’t a standard measure for the oil to fuel ratio. Various manufacturers recommend different values. You must consider this and get the right measurements. If you don’t know how to measure, buy smaller containers of gasoline that are already measured. Put the oil in a clean container, then add a gallon of gasoline and shake it well. 

Another significant difference between 2-cycle and 4-cycle engines is the sound produced when they run. 2-cycle engines are much louder, as witnessed in the ‘buzzing’ sound by chainsaws and mowers. 

Most appliances that use 2-stroke engines to operate are hand-held because of the higher power-to-weight ratio. Because they rev up faster, the amount of power output per round is higher.

In terms of cost, 2-cycle engines are cheaper to manufacture. Because they do not require valves, the cost isn’t as expensive as the 4-cycle ones. Besides, their design is simple; thus, fixing them is not as complicated and costly.

To use a 2-cycle successfully, you need to maintain it well; otherwise, you’ll have to deal with constant repairs. Not only will these depreciate them, but you’ll also be spending more money by repairing them every now and then. Monitor all parts to ensure that they are all functioning well. Take preventative actions before it’s too late and help your engine have a longer lifespan.

These types of engines are very powerful. Perhaps this is the one feature that gives them an edge over 4-cycle engines. A two-stroke and a four-stroke engine of the same size have different power outputs. Besides, two-stroke engines have a uniform torque and also operate at high speeds. They take up less space and are not as complicated in design as the 4-cycle stroke engines.

However, because of losses, the two-stroke falls short. Its spark plug frequently fouls, because of the oil present in the mixture with gasoline, meaning you’ll have to replace it more often. This will result in more costs. In addition, these engines consume more fuel, nearly half as much as the 4-stroke engines. Heat loss also makes it unattractive to use. 

Luckily, with the advancements in technology, improved versions of the 2-stroke engines are available. They try to reduce the limitations of these gasoline-powered combustion engines by filling the gaps. Most of those in the market today have fewer emissions and consume less fuel. 

Pros 

  • It is a powerful engine that runs a fast combustion revolution.
  • It is flexible enough to work in machines like chainsaws.
  • It is easy to fix and repair.
  • It is cheaper to manufacture.
  • It has low maintenance costs.

4-Stroke Engine

The 4-stroke engine gets its name from the number of times the piston strikes in upwards and downward movements during the combustion process. The piston makes four strokes in the cylinder as it moves from the top to bottom dead centers. This engine is mostly used for big machinery because they last longer and provide the best performance.

Initially, 4-stroke engines were used on big appliances such as dirt bikes, buses, trucks, tractors, lawnmowers, and go-karts. Nowadays, they are used in small appliances as well. It is not uncommon to find small engine tools with this type of gasoline-powered combustion engine.

Its crankcase has a reservoir which lubricates the engine. Here, oil doesn’t mix with gasoline. 4-strokes don’t need prior mixing of oil and fuel because the oil is kept in a separate compartment.

As compared to 2-stroke engines:

  • The main difference is in performance and maintenance. When it comes to efficiency point of view, 4-stroke engines are much better. 
  • They consume less fuel, only once in those four strokes. 
  • Another aspect not to ignore is durability. 4-cycle engines are more durable because they require less constant repairs. 
  • Additionally, they run at a lower RPM (Rotation Per Minute)
  • They are environmentally friendly as they do not pollute the environment. The injected fuel burns completely. 
  • It’s also easy to control the combustion process to help reduce the emission of toxic compounds. If you dislike noisy things, then this is the right engine for you.

Overall, 4-stroke engines are better in terms of thermal losses, mechanical friction, fuel economy, emissions, and performance. 

However, cost-wise, these engines are a little more expensive as they consist of more parts, including valves. On the other hand, 2-stroke engines only rely on two ports: the intake and exhaust ports. 

Pros

  • Quiet operation; the 4-stroke engine does not produce buzzing sounds.
  • Saves fuel as this engine consumes fuel once the 4-strokes are complete.
  • They do not require the mixing of both fuel and oil in the same compartment.
  • Environmental friendly; does not emit burnt oil and gases into the atmosphere.

Conclusion

Both engines are great depending on which angle you look at it. If you care about durability and efficiency, and then 4-stroke engines win. However, 2-stroke engines are more powerful and less costly, making them a great choice. All engine designs use the same maintenance procedures.

Your engines’ effectiveness will be determined by how you take care of them or handle the repairs. Use oils to lubricate these engines for increased efficiency and high performance.

Selecting the best engine out of the two is a personal choice. It comes down to why you need the engine and its purpose at the end of the day. Both engines are good, depending on where they are applied. If intending to use it for small capacities, a 2-stroke engine is the better choice. 

Teddy Henderson

Teddy is always fiddling with small engines, picking up thrown-out string trimmers or tearing apart dirt bikes. He shares what he learns along the way. Hopefully, you'll have less headaches than he has had by learning from his mistakes.

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