2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke (2024)

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Two-stroke engines and four-stroke engines are most commonly used all over the world for different applications. They are usually used in different vehicles. The main difference between a two-stroke engine and a four-stroke engine is, a two-stroke engine completes a power cycle in just two piston strokes while a four-stroke engine completes a power cycle in four piston strokes. This article mainly explains the 2-stroke engine vs the 4-stroke engine.

Difference between the 2-stroke engine and the 4-stroke engine

The two-stroke engine and four-stroke engine are different because they use different revolutions of the crankshaft and different numbers of piston strokes to complete a power cycle.

In a 2-stroke engine, all the four stages (intake, compression, power, and exhaust) of a power cycle complete in just two strokes of the piston while, in a 4-stroke engine, all the four stages (intake, compression, power, and exhaust) of a power cycle complete in four strokes of the piston.

2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke (1)

What is a Two-Stroke Engine?

  • A 2-stroke engine is a reciprocating engine that uses two strokes of the piston to complete power. In this engine, intake and compression processes are completed in the first stroke of the piston, while power and exhaust processes occur in the second stroke.
  • It completes one revolution of the crankshaft after the completion of one power cycle.
  • These have low weight.

2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke (2)

Read More: Types and Working of 2-stroke Engine

What is a Four-Stroke Engine?

  • A four-stroke engine is an IC engine that completes a power cycle after the completion of four-piston strokes. In this engine, intake, compression, power, and exhaust processes occur in different strokes.
  • This engine completes two revolutions of the crankshaft after the completion of one power cycle.
  • It has a quiet operation.

2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke (3)

Read More: Working of Four-stroke Engine

2-Stroke Engine Vs 4-Stroke Engine

The main difference between a two-stroke engine and the four-stroke engine is given below:

Two StrokesFour Stroke
This engine produces one revolution of the crankshaft after one power cycle.This engine produces two revolutions of the crankshaft after one power cycle.
It completes a working cycle in two strokes of the piston. It generates high torque.It completes a working cycle in four strokes of the piston. of the
The 2-stroke engine produces higher torque at a higher speed (rpm).The 4-stroke engine produces less torque at high speed (rpm).
It can’t produce higher torque at low speeds (rpm).This engine has the ability to produce higher torque at low speeds (rpm).
A 2-stroke engine has inlet and outlet ports for fuel suction and discharge. A 4-stroke engine has an inlet valve and outlet valve for fuel suction and discharge.
It has low thermal efficiency.It has high thermal efficiency.
This engine has a higher power-to-weight ratio. This engine has a lower power-to-weight ratio.
The 2-stroke engine produces more smoke.4-stroke engines produce less smoke.
When the oil ignites with the fuel, the engine needs more lubricating oil.This engine needs lower lubricating oil.
It has high wear & tear issues because of poor lubrication.These engines have lower wear & tear issues.
These engines have a low cost. Engines are cheaper and are simple for manufacturing.These have a high cost due to extra rotating parts.
They have a simple design.These have complex construction due to the additional parts.
These engines are not environmental-friendly.4-stroke engines are environmental-friendly.
They have low weight and small size.They have high weight and large size.
They produce high noise.They have quiet operation.
A two-stroke engine needs a small space for installation.A four-stroke engine requires a large space for installation due to its large size.
A 2-stroke engine has higher output power than a 4-stroke engine.These engines have lower output power than two-stroke engines.
It produces more heat due to that it requires higher lubrication and cooling.It produces less heat.
These have high heat losses.These have lower heat losses.
They have less volumetric efficiency.They have higher volumetric efficiency.
These engines have lower moving parts.These have higher moving parts.
Two-stroke engines are most common in light-duty applications.Four-stroke engines are most common in heavy-duty applications.
They are most commonly used in applications like ship propulsion, military tanks, scooters, and motorcycles.They are most commonly used in applications like aircraft, modern bikes, motorboats, vans, buses, and trucks.

How to choose which Engine is Right for You?

The right selection of an engine for a vehicle is a very important factor for the good operation of the vehicle. When you want to select a 2-stroke engine or 4-stroke engine for your vehicle, you must keep in mind the below-given factors:

  • Fuel consumption: The amount of fuel consumed by an engine or other equipment is known as fuel consumption. This consumption of fuel varies according to the engine type and speed. The quantity of the fuel consumption also specifies by the manufacturer through a performance curve. Therefore, before buying any engine, you must know the type of your engine (whether a 2-stroke or 4-stroke engine) and your engine’s fuel consumption quantity and make a purchase according to your budget.
  • Engine efficiency: The amount of fuel energy that an engine converts into useful work is known as engine efficiency. The petrol engine has efficiency from 25% to 30%. You must look at the efficiency of the engine before buying the engine because the higher the engine efficiency, the higher will be its fuel economy.
  • Emissions: The emission process in an engine occurs due to unburn gases. This is also an important factor that needs to keep in mind for the selection of an engine. In the case of a 4-stroke engine and a 2-stroke engine, the 4-stroke engine emits fewer exhaust gases than the two-stroke engine.
  • Weight: the two-stroke engine has a lower weight than a four-stroke engine. You must choose the engine according to the capability of your vehicle. It is recommended to choose a four-stroke engine for heavy-duty vehicles like buses, trucks, airplanes, vans, etc. You must choose a 2-stroke engine if you want to use your vehicle for light-duty applications like motorcycles, bikes and vans etc.

FAQ Section

Why does oil in a 2-stroke engine need to change?

In a 2-stroke engine, the oil must be changed because this oil supports cooling the cylinder and piston by their proper lubrication. If you do not properly lubricate to cylinder and piston, the metals may melt and crush each other, metals can move past each other and deform permanently, and high friction can wear parts out and clog the engine. Therefore, it is advisable to keep changing the oil to keep the engine running properly.

Why don't we have a three-stroke engine?

In order to operate the engine, four important processes must be performed:

  1. Intake
  2. Compression
  3. Power
  4. Exhaust

In the case of the three-stroke engine, you will need to select only three strokes from the above-given strokes by leaving one stroke. Such an engine is not possible because it is impossible to produce power in four operations with three strokes.

Are 2-Stroke Engines Bad for the Environment?

The 2-stroke engine is not environmental-friendly. The reason is that these engines have ports due to that waste heat leaves the cylinder and generates emissions.

Which engine is more noisy?

A 2-stroke engine generates more noise than a 4-stroke engine.

Why 2-Stroke engine is Faster?

A 2-stroke engine completes a power cycle in just two strokes instead of 4 strokes. Therefore, it completes a power cycle faster than 4-stroke engines. 2-stroke engines also have few parts and are lightweight. A good power-to-weight ratio and high engine rpm play a vital role to enhance vehicle performance.

Give some examples of a two-stroke engine.

Two-stroke engines are used in small applications such as bikes, motorcycles, boat motors, chainsaws, lawn tools, and remote-controlled cars.

Less wear and tear occurs in which type of engine?

In the 4-stroke engine, less wear and tear occurs.

Read More
  1. Working of Two-stroke Engine
  2. Working of Four-stroke Engine
  3. Types of Engines
  4. Different types of IC Engines
2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke (2024)


2-Stroke VS 4-Stroke Engine | Difference between 2-Stroke and 4-Stroke? ›

A two-stroke engine is fueled by a mixture of gas and oil and has no camshaft or valves. It fires every time the piston reaches the top. A four-stroke engine uses four separate strokes—two up and down for intake and two up and down for exhausts—and fires every other time it reaches the top.

How can you tell if an engine is a 2-stroke or a 4-stroke just by looking at it? ›

The easiest way to tell a 2-cycle engine from a 4-cycle engine is the number of fuel tank and/or oil sump fill ports. A 2-cycle engine has one fill port with a cap that has fuel pump and oil can icon.

What happens if I use 2-stroke instead of 4-stroke? ›

You cant run a 2 stroke engine long without added oil or it will seize. You can run a 4 stroke motor with fuel youve mixed for a 2 stroke. You may have oil smoke from the exhaust or foul plugs over some time, but it wont hurt the engine. You cannot run diesel fuel in a gas engine or vice versa either.

Which is more powerful, a 2-stroke or a 4-stroke engine? ›

Because combustion takes place with each revolution of the crankshaft with a 2-stroke, this format puts out more power than a 4-stroke engine and the power has more instantaneous delivery. This are some reasons why 2-stroke engines have a long history of use on many different types of motorcycles.

Do 4-stroke engines need mixed gas? ›

Two-cycle engines use a mixture of oil & gasoline in a single fuel tank. Four-cycle engines do not require mixing of oil & gasoline and have separate gasoline and oil tanks. Here are some easy ways to tell if your engine is two-cycle or four-cycle: Look at the fuel cap.

What is the main difference between a 2 stroke and 4-stroke engine? ›

The main difference between a 4-stroke engine and a 2-stroke engine is that a 4-stroke engine goes through four stages, or two complete revolutions, to complete one power stroke, while a 2-stroke engine goes through 2 stages, or one complete revolution, to complete one power stroke.

How do I know if I need 2 stroke or 4-stroke? ›

Typically, a 2-stroke engine creates more torque at a higher RPM, while a 4-stroke engine creates a higher torque at a lower RPM. The 4-stroke engine is also much quieter, a 2-stoke engine is significantly louder and has a distinctive, high-pitched “buzzing” sound.

Can I use 4-stroke engine oil in a 2-stroke engine? ›

Using a 4-stroke oil in a 2-stroke engine can therefore disrupt combustion and cause smoke formation and engine degradation.

What is the difference between 2-stroke and 4-stroke engine oil? ›

Unlike 2-stroke engine oils, 4-stroke ones do not burn with the fuel. Instead, they go around the engine. While circulating, the oil lubricates the moving engine parts, disperses heat, and eliminates impurities. Therefore, it contains different ingredients than two-stroke oils.

Why choose 4-stroke over 2-stroke? ›

Two-stroke engines are also easier to start in cold temperatures, making them ideal for use in snowmobiles. However, four-stroke engines produce more torque at lower rpm, generally have better durability than high-revving two-stroke engines and also provide improved fuel efficiency and lower emissions.

Why is 2-stroke called 2T? ›

What does 2T mean in 2 stroke oil engines? - Quora. The T stands for "Temps" It's a French thing... And you'll see a T used after 4 in some placea ita nothing but strokes in french... 2T or 2-stroke oil or Petroil is a special type of oil made for use in crankcase compression two stroke engines.

Do 6 stroke engines exist? ›

Subsequently, other six-stroke engine designs were explored, such as Dyer, Bajulaz, Velozeta, NIYKADO, Crower, and various two-piston designs (Gupta et al. 2018; Nimsiriwangso et al. 2019). These designs aimed to improve fuel consumption, increase power output, reduce pollution, and offer fuel versatility.

What are the disadvantages of a 4-stroke engine? ›

Disadvantages of a 4-Stroke Engine

Costlier repairs and maintenance because of higher complexity and larger number of parts. Generates less power than an equivalent 2-stroke engine. Has gears, timing belt or timing chains that might cause complications during maintenance. Needs regular maintenance.

What happens if I put 2-stroke fuel in a 4-stroke engine? ›

Two stroke fuel in a four stroke engine tends to run hot due to running lean, the jets are setup for all fuel and some of that area is taken up by oil so the fuel mixture is lean.

Can I use any 4 stroke oil in my lawn mower? ›

Automotive oil is perfectly acceptable and SAE-30, 10W-30, or 10W-40 function well in practically any 4-cycle lawnmower engine. Change it annually (one of the big shortfalls in lawnmower maintenance is not bothering to change it at all). Avoid using the low viscosity oils such as 0W-20 / 5W20.

Is it bad to run a 4 stroke out of gas? ›

If it's a carburetted four stroke, you can pretty easily run it out of fuel at the end of the day just as a precaution, although it's not a 'must do' if you're using the boat again regularly.

How can I identify a two-stroke engine? ›

Explanation: The two-stroke engine is identified by the absence of valves. Almost all two-stroke engines do not have valves. This makes the two-stroke engine easy to produce and maintain.

How to identify a 4-stroke engine? ›

Look for stickers labeling the equipment (e.g., "Four Cycle" or "No Fuel Mixing"). Look for an engine oil fill cap. Only four-cycle engines have a separate engine oil reservoir on the back or side, with another cap (usually yellow) for checking & filling the oil reservoir.

How do you know if a 2 stroke is 4 stroking? ›

Four-stroking is a condition of two-stroke engines where combustion occurs every four strokes or more, rather than every two.

How do you determine engine stroke? ›

If piston of the engine cylinder travels from TDC to BDC, then it's said to be one stroke. TDC is top dead Centre and piston is at the upper most position in the cylinder. BDC is bottom dead center when piston is at lower most position in engine cylinder. Stroke length is the distance between TDC and BDC.

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