What is the difference between a two stroke engine and a four stroke engine. Two-stroke and four-stroke internal combustion engine

piston stroke between two dead spots is called a beat that equals a turn crankshaft 180 degrees. Accordingly, two-stroke motors are distinguished (the duty cycle occurs in one cycle) and four-stroke (a cycle in two cycles). The differences between the two types of motors are quite serious, and, as a result, this directly affects their use in various mechanisms.

Two stroke motors

In a two-stroke engine, one revolution of the crankshaft is enough to complete the work cycle. This revolution, in turn, is carried out in two stages (tact) - compression and expansion, hence the motor got its name. Two-stroke engines are distinguished by the absence of valves, the role of which is performed by the piston. In general, the value of the piston in such motors is very large: moving, it opens and closes the purge windows (both inlet and outlet). If we externally compare two-stroke and four stroke engine, then the construction of the first variant is much simpler. You can verify this by reading the definition below. four-stroke motor.

Four stroke motors

The working cycle of a four-stroke engine has four stages (cycles). In addition to compression and expansion (the second and third stages, respectively), an intake (first cycle) and an exhaust (fourth cycle) are added. At the first stage, the piston moves from one dead center to the other - from the bottom to the top. The intake valve opens, and the engine cylinder enters required amount fresh fuel air mixture. On final stage(exhaust) piston reaches top dead points, and Exhaust valve closes. After that, the working cycle of the four-stroke engine begins anew.

Four stroke engine

Comparison

The difference in the number of cycles is very important, but far from the only difference between two-stroke and four-stroke motors. There is still whole line differences that come from the advantages and disadvantages of one or another engine.

Here are the main differences:

• Two-stroke engines weigh an order of magnitude less, even if the amount of horsepower is the same. A vivid example: at fifteen horsepower two stroke engine will weigh 36 kilograms, and a four-stroke - almost ten kilograms more.
• The design of four-stroke engines is noticeably more complex, and the production process is longer. All these factors have a direct impact on the price - four-stroke engines are more expensive.
• Transportation and operation of a two-stroke engine is noticeably easier. It can be transported in almost any position, and to use it, it is enough to get it, install it and start it.
• The fuel consumption of a two-stroke engine is about one and a half times greater (for the same horsepower).
• Four-stroke engines, if you start them on full power, work a little quieter than the two-stroke version. The difference in noise is negligible, but it exists, and this is where four-stroke engines have an advantage.
• Another advantage of four strokes is less vibration and smoke. Moreover, the second difference is extremely important for engines, because most people choose a motor that produces less smoke (not so harmful to human health and less pollution for environment).

Findings site

1. Two-stroke engines weigh less.
2. Four-stroke engines are more complex and more expensive.
3. Different complexity in transportation and operation.
4. Different fuel consumption for the same amount of horsepower.
5. Four-stroke motors make less noise during operation.
6. Two-stroke engines emit more smoke during operation.

Cycle ICE operation(engine internal combustion) consists of several processes, the production product of which is the release of power (energy), and power, in turn, affects crankshaft(crankshaft) engine.

The cycle of operation of the internal combustion engine includes:

• filling the cylinder with fuel;
• compression fuel mixture;
• fuel ignition;
• expansion of gases with subsequent cleaning of the cylinder from them.

Piston movement performed in one direction (down or up) is called the engine stroke. During one revolution of the crankshaft, two strokes occur. The working stroke of the piston is the stroke at which useful work occurs as a result of the expansion of the burnt gases.

Those engines in which the duty cycle consists of two cycles (for one revolution of the crankshaft) are called two-stroke. The same engines, in which the duty cycle consists of four strokes (for two revolutions of the crankshaft), are called four-stroke . Four- and two-stroke engines can be both diesel and gasoline (carburetor). So what are the main constructive and operational features four-stroke and gasoline two-stroke internal combustion engines? Familiarization with the principle of operation of each of them will help to better understand this.

The principle of operation of a four-stroke engine

Work in a four-stroke engine is completed in 4 cycles: fuel injection, fuel liquid compression, liquid ignition and expansion of the stroke, combustion products release.

The piston moves from TDC (top dead center) to BDC (bottom dead center) when fuel is injected. This stroke also opens the intake valve using the camshaft cam ( camshaft). Through this valve fuel mixture enters the engine cylinder.

When the piston reverses (from BDC to TDC), the fuel mixture is compressed and its temperature rises rapidly.

A spark forms between the electrodes of the spark plug (a fraction of a second before the end of compression). The fuel mixture is ignited and in the process of combustion emits combustible gases, which, under the action of high pressure push down the piston. This is called the power stroke of the engine. All useful work is done in this cycle.

When the piston returns from bottom dead center, the intake valve will open and the moving piston will be able to push combustion products (exhaust gases) out of the cylinder. After the release occurs, the valve closes at TDC and the cycle repeats again.

The working process of a two-stroke engine includes two cycles: fuel compression and expansion (ICE stroke). During expansion and contraction in a two-stroke engine, combustion products (exhaust gases) are released and fuel liquid is injected. This is the main difference two-stroke internal combustion engine from four stroke.

The piston moves from BDC to TDC during compression. However, first the purge window must close (through it the fuel mixture enters the cylinder), and then the exhaust window (through it exhaust gases are emitted). When all conditions are met, the mixture of gasoline and air will be compressed (air-gasoline mixture). Parallel to this process, a vacuum occurs in the crank chamber, which sucks the next portion of gasoline from the carburetor. As soon as the piston reaches TDC, the mixture will ignite from the spark that is generated from the candle. Then the piston moves down under the action of the formed gases, and at the same time produces useful work by rotating the crankshaft.

During the working stroke, pressure increases in the crank chamber, which compresses the fuel that has entered it during the previous cycle. As soon as the upper surface of the piston (its O-ring) reaches the exhaust port, it will open and exit into the exhaust silencer. Moving on, the piston will open the purge window and the fuel mixture, which was previously in the crank chamber under pressure, will enter the cylinder. During the intake process, the mixture will displace all residues of combustion products and carry out the so-called purge, filling the entire over-piston space. The work cycle will repeat again as soon as the piston reaches BDC.

Design and operational differences

The main difference between these complex devices is that they differ in the mechanisms of gas exchange, that is, the mechanisms for the release of exhaust gases and the supply of a fuel-air mixture. In a four-stroke engine, there is a special gas distribution mechanism that closes and opens the exhaust and intake valves at a certain time. With its help, the cylinder is filled and cleaned.

In a two stroke engine there is no such mechanism, and all cleaning and filling processes are performed in parallel with the expansion and compression cycles. The piston all this time is near the BDC. For these processes, two holes are located in the walls of the cylinder: a purge and an inlet. The purge hole is responsible for the release of combustion products, and the inlet is responsible for supplying fuel to the cylinder. The gas distribution mechanism, as we have already said, is absent in such an engine, and therefore there is no complex valve system. This makes the two-stroke engine significantly lighter and simpler.

Liter power. In a four-stroke engine, the entire power stroke is completed when the crankshaft makes two revolutions, and in a two-stroke engine, each revolution of the crankshaft represents a power stroke. Theoretically, a two-stroke engine should have a greater (2 times) liter capacity of an internal combustion engine than a four-stroke one. Liter power is usually called the ratio of engine power to its displacement.

However, practice shows that this is not always the case. As a rule, this ratio is in the range from 1.5 to 1.8. This happens for a number of reasons: the piston does not fully use its stroke due to expansion, the mechanism for releasing exhaust gases in the cylinder is inferior to the mechanism of a four-stroke engine, part of the power is spent on scavenging the cylinder and other features of gas exchange in a two-stroke engine.

Fuel consumption. Although a two-stroke engine outperforms a four-stroke engine in terms of specific and liter power, it is significantly inferior to it in terms of economy. Coming from the crank chambers in a cylinder fuel liquid, mixed with air, displaces exhaust gases. Therefore, some part of the fuel is removed with the exhaust gases, getting into the exhaust ducts, and, accordingly, the engine loses some of its useful work.

Lubricant. Two-stroke engines differ in the principles of engine lubrication from four-stroke ones. To lubricate a 2-stroke model, it is necessary to create a special mixture of gasoline and engine oil (5:1, as a rule). This mixture of gasoline, air and oil perfectly lubricates all engine elements: cylinder mirror, crankshaft and connecting rod bearings, because it circulates not only in the crank, but also in the piston chamber. When the mixture ignites, the oil that is on this moment has the appearance of small droplets, burns as quickly as gasoline. All combustion products will be removed with exhaust gases.

How to properly lubricate

In order to mix gasoline with oil, two methods can be used. A simple one is to mix the oil with fuel before pouring into the tank, and a complex one involves a separate supply of fuel and oil. In the latter case, the oil-fuel mixture will form in the intake pipe located between the cylinder and the carburetor.

Also in the second case the diesel or petrol engine must have an oil reservoir and a pipeline that must be connected together with the plunger pump. Such a pump will supply oil in the right amount (depending on the amount of gasoline and air). The position of the "gas" supply knob directly affects the performance of the pump. How less fuel is supplied, the less oil will flow and vice versa.

Engine manufacturers claim that such a lubrication system is more correct and perfect. It reduces oil consumption, reduces the amount of smoke, reduces the formation of carbon deposits, since at low loads the ratio of gasoline to oil reaches only 200: 1. Such a system is actively used by manufacturers of two-stroke scooters or motorcycles of small cubic capacity.

On 4 stroke models oil is supplied separately from gasoline and does not mix with it. For this, it is used classical system grease, which consists of: filter, valves, oil pump and pipeline. Instead of an oil barrel, there may be a crankcase ("wet" lubrication system) or a separate reservoir ("dry" lubrication system).

Almost all engines have oil filters that clean the fluid from wear products. various parts. To cool the oil (it tends to heat up during operation), you can install a cooling radiator.

Since two-stroke engines during operation, the oil tends to burn out (unlike four-stroke ones), then it must have special properties. For example, oil for two-stroke models should not leave a lot of carbon deposits, in the form of soot and ash, while oil used in four-stroke engines should provide stability for as long as possible.

Parameter comparison

Thanks to its light weight, easy maintenance and high power density two-stroke models have a wide range of applications. In many petrol devices(mowers, chainsaws) there is not even a question about which ICE model use. However, two-stroke ones are losing ground due to high taxi and noise. Therefore, it is considered that each model has its pros and cons and it is better to choose which engine is best to use in a particular case, according to the circumstances.

Piston engines have taken a leading position in human economic activity. The attempt to make a 4-stroke engine run more efficiently has led to all sorts of possible and improbable engine designs and how they work. One of this variety of piston schemes with a modified work process turned out to be viable and was widely introduced into technology.

Depending on the number of cycles of the working ICE cycle are divided into two main groups: two-stroke and four-stroke engines. In two-stroke motors, there are only two of them: the compression stroke and the expansion stroke or power stroke. Four strokes have four: intake, compression, expansion or stroke, and exhaust. At first glance, it may seem that the first option is more advantageous, because the duty cycle is repeated with each revolution of the crankshaft and the energy is generated twice as intensively, but in fact this is not entirely true, as is directly evidenced by the limited use of two-stroke engines, especially in large machines, installations and units with high level fuel consumption. In order to understand the causes of energy loss during the operating cycle, one must consider the operation of the engine.

Engine operation process

The duty cycle of a 2-stroke engine includes the following sequence of actions:
On the compression stroke, the piston in the cylinder moves from bottom dead center (BDC) to top dead center (TDC). Through the purge window, the fuel charge enters the over-piston space - the combustion chamber, after which the piston closes this window. Rising higher, it gradually covers the outlet window through which combustion products are removed. In this case, a vacuum is formed in the space under the piston (crank chamber), and it is filled with a new portion of fuel. When the piston reaches TDC, the compressed fuel charge ignites;
- on the expansion stroke, the gases formed during the combustion of the fuel put pressure on the piston, it goes down, opening first the exhaust window, and then the purge. Through the first window, the expanded gases enter the muffler and are discharged outside. At the same time, when the piston moves down, the pressure in the crank chamber filled with fuel increases. Fuel is pushed up into the cylinder, filling the space above the piston and pushing out the remaining exhaust gases. Then the cycle repeats.

This principle of operation allows two-stroke engines to do without the gas distribution system characteristic of four-stroke engines, which controls the intake and exhaust valves. On the one hand, this simplifies the design and reduces weight, but on the other hand, gas exchange in the combustion chamber is far from ideal. In a two-stroke mode of operation, when the cylinder is purged, along with the exhaust gases, a certain amount of unburned fuel enters the muffler, which leads to its overspending and increases toxicity. exhaust gases.

Types of gas distribution system

Since the purge windows in the cylinder are sometimes located at the same level, gas exchange inside the cylinder is difficult, not the entire volume of the cylinder is purged with a fresh portion of the air mixture, and part of the exhaust gases remain in the cylinder. In order to change the exhaust gases to a fresh portion of air more efficiently and quickly, there are design features of the piston and the location of the purge windows in the cylinder. There are several options for purging cylinders:

Loop purge

Loop purge, in turn, is divided into loopback, deflector and high-rise. All these species have one significant disadvantage: Fuel overrun due to removal of unburned fuel charge during purge.

U- or L-shaped purge

U- or L-shaped scavenging is more efficient in terms of fuel economy, but the temperature near the exhaust port increases significantly. The design feature is that for its implementation, a two-cylinder version of the motor is required. One pair of cylinder-piston acts as inlet gases, and the other pair acts as exhaust gases.

Valve or valve-slot purge

Valve or valve-slot purge, unlike other types, requires a timing belt, which is controlled by valves. The valve can be used both to supply a charge and to remove combustion products. When valve-slot purge through the valve in the cylinder head, exhaust gases are removed, and through the windows (slots) fresh charge. This reduces fuel consumption and reduces the toxicity of exhaust gases, but complicates the design of the engine and can disrupt normal mode charge combustion due to elevated temperature.

Direct-flow purge

Direct-flow scavenging is used in engines with two pistons located opposite each other in a horizontal position. In this case, each piston in the course of its movement opens and closes its “own” valve: one piston is responsible for the charge inlet, and the second for the removal of gases. The combustion chamber in this case is the space between the pistons. This option provides for a more complex KShM, and heat inside the cylinders requires additional cooling and more durable items. At the same time, this is the most effective method purge, which ensures complete removal of exhaust gases with minimal loss of fuel charge.

Features of two-stroke engines

A feature of two-stroke engines is the absence of a lubrication system. Oil for lubricating the working surfaces of rubbing parts is delivered to them directly with the fuel mixture. There are two options for obtaining such a mixture: initially pour a pre-prepared “cocktail” of fuel and engine oil into the tank, or mix them in the inlet pipe, where they enter separately. The ratio of fuel and oil is in the range from 1:25 to 1:50. Engine oil, like fuel, burns out during the working cycle, and the products of its combustion are removed along with the exhaust gases.

In terms of power, two-stroke engines are indeed more powerful than their four-stroke competitors. Ideally, their power with the same displacement should be 2:1, respectively, but in reality, due to poor-quality gas exchange in the cylinders, this ratio is 1.5:1. The specific power or power-to-weight ratio of the engine is also higher for two-stroke engines, because their weight is much lighter, and the design is simpler.

But fuel consumption in two-stroke engines is higher than that of four-stroke ones. Due to an imperfect cylinder scavenging system, part of the fuel mixture literally flies into the pipe. For this reason, such engines are practically not used in cars, heavy equipment or powerful power plants consumed by a large number of fuel.

Another point that distinguishes a two-stroke engine from a four-stroke one is the process of fuel combustion. Since the outlet window opens almost immediately after the charge has been ignited, it is necessary to allow sufficient time for it to complete combustion. In a four-stroke engine, a whole work cycle is given for the combustion process, but here it is only a fraction of a second. To achieve maximum efficiency, in gasoline engines it is necessary to accurately determine the ignition timing, and in diesel engines - to control the time of fuel supply. IN modern models this is achieved through the use of electronics.

Two-stroke engines can be either gasoline (carburetor or injection) or diesel. The difference in the principle of their operation lies in the fact that in the first case, a fuel charge (a mixture of air with fuel) is immediately supplied to the cylinders, and in the second, first air, and at the end of the first cycle, fuel that ignites upon contact with hot air. Gasoline engines widely used in motorcycles, small cars, as well as in lawn mowers, chainsaws and other units with internal combustion engines. Diesel engines have found application in shipbuilding; earlier they were also used on diesel locomotives, tanks and were successfully used in aviation on Junkers bombers. Now shipbuilding is almost the only area of ​​their application, where their slow speed and power, not exceeding 100 thousand hp, came in handy. Unlike four stroke two-stroke diesels do not have separate combustion chambers, which would further complicate their design, so that diesel fuel is supplied and mixed with air directly in the combustion chamber.

So, two-stroke engines have a number of advantages:
— simple design;
- light weight;
- lower loads on structural elements;
— lack of lubrication and timing system;
- more liter power compared to four-stroke.

At the same time, two-stroke motors have disadvantages:
— increased consumption fuel;
— toxicity of exhaust gases;
- a smaller resource in comparison with a four-stroke;
- noise during operation;
- the need to prepare a fuel-oil mixture, which not only complicates the fuel supply system, but also increases oil consumption.

conclusions

From the foregoing, we can conclude that two-stroke engines can be used in cases where fuel consumption does not matter, but such characteristics as low weight and simplicity of design are important. These are ideal options for portable units, small cars as well as motorcycles and mopeds. Compact dimensions two-stroke engines allowed them to thoroughly take a place in a field that would seem completely far from the field for which internal combustion engines were created - in modeling.

Recently, two-stroke engines have become increasingly popular due to the use of electronic systems in their design. This allows you to reduce the toxicity of exhaust gases, regulate the processes of supply and combustion of fuel, which makes the engines more environmentally friendly. So in the near future their scope may expand significantly. As early as the beginning of the 20th century, the development of diesel two-stroke engines began. One of the most successful schemes was developed by Hugo Junkers, and in the 60s of the 20th century, Soviet engine builders also produced an example of an engineering miracle - an opposed 2-stroke diesel engine 5TDF with 700 hp

The design of two-stroke engines has huge reserves in terms of power and efficiency. But due to design features, they could not be implemented in mechanical. Quite possible electronic systems will help "two-stroke" to take a leading position among internal combustion engines in the near future.

Dear friend, today we will talk about what a four-stroke engine means. About the history of its invention, the principle of operation, features, technical specifications and areas of application.

Of course, if you have driver's license, then you at least heard this term when you studied at a driving school. But it is unlikely that then they began to delve into all the subtleties, so now is the time to figure out what is happening there under the hood of your iron horse.

There were already engines in the 19th century, but they were mostly large machines powered by steam. Of course, they partially provided for the developing industry, but had many shortcomings.

They were heavy, had low efficiency, large dimensions, it took a long time to start and stop, skilled workers were needed for operation.

The industrialists needed new unit without these shortcomings, they already understood what a four-stroke engine means. And how, under certain conditions, it can be used to increase profits.

It was developed by the inventor Eugene-Alphonse Beau de Rocha, and in 1867 Nikolaus August Otto embodied it in metal.

At the time, it was a marvel of technology. The internal combustion engine was characterized by low operating costs, small size and did not require the constant presence of maintenance personnel.

The device worked according to a special algorithm, which is now called the "Otto cycle". 8 years later, after the launch of the first instance, the Otto company has already produced more than 600 power plants a year.

Very quickly, due to autonomy and compactness, internal combustion engines became widespread.

What is the engine made of?

To understand the principle of operation, let's get acquainted with the main components of the engine:

• (includes crankshaft, pistons, connecting rods) - it is necessary to convert the reciprocating movements of the piston into rotational movement of the crankshaft;
• the head of the block along with the gas distribution mechanism, which opens the intake and exhaust valves in order for the working mixture to enter and the exhaust gases to exit. The timing may include one or more camshafts, which consist of cams for pushing the valves, the valves themselves, and valve springs. For stable operation four-stroke engine, there are a number of auxiliary systems:
• ignition system - for igniting the combustible mixture in the cylinders;
• intake system - for supplying air and working mixture to the cylinder;
• fuel system - for continuous supply of fuel, obtaining a mixture of air and fuel;
• lubrication system - for lubrication of rubbing parts, as well as the simultaneous removal of wear products;
• exhaust system - to remove exhaust gases from the cylinders, reduce exhaust toxicity;
• cooling system - to maintain the optimum temperature of the engine.

What does a four-stroke engine mean and why four strokes

1. Now that you have more or less an idea of ​​​​the design of a four-stroke engine, you can consider the workflow.
   It consists of the following stages: inlet - the piston moves down, the cylinder is filled combustible mixture from the carburetor through inlet valve, which are opened by the camshaft cam. When the piston moves down, a negative pressure is created in the cylinder, thereby sucking in the working mixture, namely air with fuel vapor. The intake continues until the piston reaches BDC (bottom dead center). At this point, the intake valve closes;
2. compression or compression - after the BDC is reached, it begins to move up to the TDC (top dead center). When the piston moves up, compression occurs, the working fuel-air mixture compresses, the pressure inside the cylinder increases. Inlet and outlet valve closed;
3. power stroke or expansion - at the end of the compression cycle (at TDC), the working mixture is ignited by a spark in the spark plug. The piston from the microexplosion rushes to the BDC. During the movement of the piston from the TDC to the BDC, the mixture burns out, and the gases increasing in volume push the piston, performing useful work. It is for this reason that the movement of the piston in this cycle is called the working stroke. Inlet and outlet valve closed;
4. exhaust gas release - in the final fourth stroke, the exhaust valve opens, the piston rises in top point and pushes the products of combustion out of the cylinder exhaust system passing through the muffler, they enter the atmosphere. After the piston reaches TDC, the exhaust valve closes, then the cycle repeats. These four cycles represent the duty cycle of the motor. The stroke is also called the movement of the piston up or down. One revolution of the crankshaft corresponds to two strokes, and two revolutions to 4 strokes. Hence the name of the four-stroke engine.

What determines the power of a four-stroke internal combustion engine

Everything seems to be clear here - power piston engine basically defined:

1. cylinder volume;
2. the degree of compression of the working mixture;
3. rotation frequency.

You can also increase the power of a four-stroke engine by increasing throughput intake and exhaust strokes by increasing the diameter of the valves (especially intake).

Also maximum power is obtained with the maximum filling of the cylinders; for this, turbines are used for forced air pumping into the cylinder. As a result, the pressure in the cylinder increases and, accordingly, Engine efficiency increases significantly.

Current Application

Four-stroke engines are either petrol or diesel. These engines are used in transport or stationary power plants. It is recommended to use such an engine in cases where it is possible to adjust the ratio of speed, power and torque.

For example, if the engine is paired with an electric generator, then you need to maintain the desired speed range. And when using intermediate gears, a four-stroke engine can be adapted to loads within a fairly wide range. That is to use in cars.

Let's go back to the origins of its creation. A very talented engineer Gottlieb Daimler worked in the group of the inventor Otto, he understood what a four-stroke engine means, its development prospects, and proposed to build a car based on a four-stroke engine. But the chief did not consider it necessary to change something in the engine, and Daimler, carried away by his idea, left the master.

And after some time, together with another enthusiast Karl Benz in 1889, they created a car that was driven precisely by the gasoline four-stroke internal combustion engine of the inventor Otto.

This technology is still successfully used today. In cases where power point works on transient modes or modes with partial power removal - it is indispensable, as it ensures stable stability of the process.

Now, dear friend, are you in in general terms know what a four-stroke engine means, where it is used. Now you are head and shoulders above. But do not be stingy with the information received, share it with your friends. Social media buttons are at your service.

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Which outboard motor choose? (comparison of two and four-stroke motors.)

The age-old dispute, which motor is better than a two-stroke or four, now and then flares up again and again on different fishing resources. Foaming water motors alone prove that a two-stroke is “just what the doctor ordered!” Others, on the contrary, argue that it cannot be better than a four-stroke!

I will say right away that both types of motors have their advantages and disadvantages, and when buying a PLA, you need to proceed from what you need for your conditions of use. That is, after comparing 2 and 4-strokes, the choice should be yours. And I, in turn, will try to give strong arguments "for" and "against" both designs.

Environmental friendliness.

A two-stroke outboard motor is designed in such a way that the oil that lubricates the crankshaft inevitably enters the combustion chamber. Ideally, it should burn there along with gasoline and burnt out as exhaust gas. But, as they say, there is nothing perfect in the world, and designers are also people, so in reality everything is a little different. The new fuel enters the combustion chamber at almost the same time as the exhaust gases are expelled. This then leads to the entry into the exhaust gas of a working or incompletely burned mixture, which ultimately ends up in a reservoir.

Regarding the norms of the law in the United States and the countries of the European Union, it seems that the sale and use of two-stroke engines is prohibited due to increased environmental pollution standards. So if you buy a motor and want to go all over Europe under it, then definitely take a four-stroke. In Russia, there are no prerequisites for the adoption of such norms and laws yet, our government is more interested in winter - summer time and any other crap, ecology and a ban on the sale of networks are not included in their plans, like many other aspects of improving the environment and raising the standard of living of the population. It follows that we can safely walk with two-stroke engines. There is one more important point left, if you are an ardent environmentalist, then you have already received the answer which motor is better.

Motor weight

In four-stroke engines, every fourth stroke is a working one. For two-stroke engines, accordingly, every second will be a worker. Ideally, it should be that two-stroke engines are twice as powerful as four-stroke ones (with the same volumes of combustion chambers). In fact, everything is a little different. Design flaws, such as, for example, getting into working mixture spent and fresh mixture into the exhaust, lowers this figure by about 1.7 times. But, one way or another, it turns out that in order to achieve the same power on the shaft (namely, we are interested in it), we need a smaller two-stroke engine than a four-stroke one. And if the size is smaller, then the motor is lighter. That is, if the main criterion when choosing a motor is its weight, then you should be inclined to buy a two-stroke motor. Where is the weight really important? In the event that your boat is at the boat station or in the garage on a trailer in the assembled state, and you hung the motor on the transom, forgetting about it until the time of service or repair ... In this case, does the weight of the motor matter? I think no!

But if you inflate the boat every time on the shore, each time installing the motor on the transom, and take it off after fishing or walking, and even store the kit on the balcony ... then, I think everyone will agree that weight matters.

The shorter the boat, the greater the role of weight at the stern, in which case you will have to constantly load the bow in order to safely approach the engine or get into planing mode.

If you use a large PVC boat and you have to assemble - disassemble it on the shore, and at the same time hang 15 mares on the transom, then a thirty-kilogram (two-stroke) motor can still be picked up alone, and it will not be easy to screw a 50kg (four-stroke) one without assistance, unless you are a bodybuilder or a heavyweight weightlifter.

Saving

For the same power, four-stroke outboard motors are more expensive than their two-stroke counterparts. The price difference can be up to 50%. All this is due design features four stroke.

Fuel

It is no secret that the efficiency of a four-stroke engine is higher, it eats less gasoline and oil. Again, it's all about the design of the motors. How important it is for you, decide for yourself. If you go to the pond a couple of times a month, then perhaps your grandchildren will pay off the price difference, but if you go out on the water every day and the engine rests only during the freeze-up period, then the fuel costs will be tangible and then you need to think about which engine is better.

There is an opinion that a four-stroke engine has a much longer resource than a two-stroke competitor. In fact, these statements are solid theory. Let's assume that the motor resource of the engine is declared in 2000 m.ch. To establish this in practice, it is necessary to walk around the pond back and forth throughout the entire season of “liquid water”, moreover, around the clock. Despite the rest and weather. Or ride three seasons, every day, eight hours a day. For completeness of the data, it is necessary to use several outboard motors. What will be the cost of such a check, it is even difficult to imagine. In fact, if there were any tests, they are too conditional, since they were most likely sponsored by the manufacturer of the PLM, which means it is difficult to judge the reliability of the data. So it is difficult to judge the motor resource of outboard motors, since they were most likely calculated only on a computer or paper. In this regard, it is very problematic to say with certainty which motor is better.

Maintenance and repair

Any mechanism needs repair over time. And here I think it is clear that the greater the cost of the motor, the more expensive the spare parts for it. If your hands grow from where you need to, and you are able to understand the mechanisms yourself, maintain and repair the engine, then it is preferable to stop at buying a two-stroke engine. These motors are simple, there are more specialists on them, they are longer taken out of production. There are craftsmen who can perfectly tune two-strokes right on the water.

Other nuances

Motor noise. The noise level of two-stroke engines is higher than that of their four-stroke counterparts. This is especially noticeable at full and very low speed. Therefore, if you are going to trolling, then a four-stroke motor will be preferable. The two-stroke also smokes more, due to the presence of oil in the mixture, which turns trolling with a tailwind into an uncomfortable pastime. Here you will quickly decide on the choice of outboard motor, if weight is not of key importance.

Oil. A two-stroke engine uses a mixture of gasoline and oil, while a four-stroke engine runs on pure gasoline. And some, when choosing a motor, see some great difficulties in mixing oil with gasoline. To break in the PLM, the proportions are 1 to 25, and after the break-in is 1 to 50. Who has problems with arithmetic so much that they cannot divide a liter by 25 or 50. Many immediately pour the required amount of oil into the canister at the gas station, and until they get to reservoir, gasoline and oil are mixed, and when moving through the reservoir, the mixture continues to slosh. And now those oils that are produced for two-stroke engines are self-mixing.

Transportation. Four-stroke motors must be transported in a certain position, while two-stroke engines can be transported as your heart desires, even upside down. This is due to the fact that in four-stroke engines there is oil in the crankcase and, if transported incorrectly, it can leak out. Many two-stroke supporters mention this fact as very significant when choosing a motor, although in fact it does not affect the speed or power of the motor, and I don’t remember at all who was so inconvenienced by transporting a four-stroke motor that it was worth focusing on this .

Planing. To get on the glide, you need the “right boat”, designed not for quiet walks in displacement mode. Trying to bring such a boat into planing mode will not lead to anything good.

Also, the output to the planing mode depends on the weight of the boat with all its contents and the number of horses under the hood. The calculation is approximately such that 25-30 kg of weight should fall on one mare. Since the weight of the motor is also taken into account when calculating the exit to planing mode, the smaller its weight, the more likely it is to go on planing. The other side of the coin is that the less weight, the less horses. Approximately, you can say this - if you have a small PVC boat with a transom, then it is better to take a five in 2 cycles, with it it is more likely to go on a gliding than with a 4-stroke. If we are talking about ten mares or fifteen, then in this case the weight does not play a big role, and if in other respects the weight is not important to you, then there is no point in bothering.

I hope the article turned out to be useful to you and many questions about choosing a PLM have disappeared.

Sincerely, Mamba!