Which motor to choose two-stroke or four-stroke? Differences between a two-stroke engine and a four-stroke engine.

What can be added to the tons of material written on this topic? Another banality?

Nevertheless, having stumbled upon another forum battle within the framework of the permanent war of "sharp-pointed and blunt-pointed", I decided to speak out and give some figures.

Let's try to figure it out quickly.

Advantages

What are the advantages of 4 and 2 stroke engines?

Advantages of two-stroke outboard motors

• less weight;
• better dynamics;
• lower price;
• ease of maintenance and repair (as a result of simplicity of design);
• b O Great reliability (also as a consequence of the simplicity of the design);

Advantages of 4-stroke outboard motors

• less noise during operation (especially on low revs);
• lower fuel consumption.

Not all 2-stroke engines need to pre-mix gasoline with oil. Therefore, the absence of this procedure during the operation of 4-stroke engines, I did not write them down as an advantage. I also do not give the traditional argument about the stunning resource of 4 cycles due to the lack of both solid evidence for this statement and the irrelevance of this problem for the vast majority of water motorists.

He also did not mention anything regarding the environmental friendliness of engines. It's irrelevant for now. Whether this is good or bad, but the question is not posed point-blank, and there is no reason to think that something will change here in the foreseeable future.

Dry residue

So, to the question why do we need to overpay for four cycles, we, it turns out, can answer: “It is quiet and economical.”

And now let's decide whether this "quiet and modest girl" is worth the cost of a wedding?

It is easy to talk about "silence" to a person who is not familiar with the subject of discussion. Yes, at low, up to 1000-1200, revolutions, the four-stroke is quiet, and even almost inaudible at idle - I remember a couple of times, at first, the already working engine tried to start with the key. 🙂

However, everyone who has operated both 2-ton and 4-ton PLM will tell you that starting from 4000 rpm. the difference in noise disappears and becomes insignificant towards the upper limit of the maximum.

Yes, if it is significant (there are “tractors” among 2-stroke engines), how long do we listen to the noise of our motor? Most of the rest / departure the engine is muffled.

But low noise has never been the decisive argument of the apologists of the four cycles. Economy has always been a reinforced concrete argument in a dispute with thinkers from the opposite camp.

The economy must be economical

four stroke engines consume less gasoline - and this is an indisputable fact. Less gasoline - less loading of the boat, less cost departure.

However, 4-stroke engines of the same horsepower tend to be heavier and more expensive than their 2-stroke counterparts. Thus, whatever one may say, we must know:

1. does the fuel economy pay for the high cost of the motor itself;
2. whether the difference in the weight of the required fuel compensates for the difference in the weight of the motors.

Yamaha, as well as some other manufacturers, publish reports with the results of evaluation of the performance of their PLA. This information is freely available online at http://yamahaoutboards.com/owner-resources/performance-bulletins

To evaluate the economic effect of using a four-stroke engine, I needed data on the consumption of a pair of 2-ton and 4-ton PLA with the same number of horses. I stopped the choice on two medium power engines:

1. 2-t: Yamaha 50TLR (we know it as Yamaha 50HETOL).
2. 4-t: Yamaha F50TLR (we have Yamaha F50HETL).

Two-stroke "fifty dollars" was tested on a boat Sundance FX 17 Flicker(length 5.21 m; width 1.98 m; total weight during testing 710 kg).

Four-stroke - by boat Key West 166SK(length 4.95 m; width 1.83 m; total weight during testing 623 kg).

Please note that the boat on which the two-stroke is installed (Sundance FX 17) is slightly longer and wider than the other and also heavier by 83 kg. But these are the closest in terms of parameters and type of watercraft that I was able to find for this power. Okay, let's give four bars a little head start. 🙂

Test results were these:

Yamaha 50TLR				Yamaha F50TLR
rpm	speed km/h	consumption l\h	consumption l\100 km	rpm	speed km/h	consumption l\h	consumption l\100 km
1000	6,28	1,89	30,16	1000	6,44	1,51	23,52
1500	8,53	3,41	39,94	1500	7,72	2,27	29,40
2000	10,94	4,54	41,51	2000	9,17	3,79	41,27
2500	12,07	6,44	53,32	2500	11,59	4,92	42,47
3000	19,31	7,95	41,16	3000	16,74	6,81	40,71
3500	29,29	9,46	32,31	3500	28,97	6,81	23,52
4000	37,82	10,98	29,03	4000	35,89	8,71	24,26
4500	44,42	11,73	26,42	4500	42,16	10,60	25,14
5000	51,98	16,28	31,31	5000	46,99	13,25	28,19
5500	57,78	21,58	37,35	5500	51,34	17,79	34,66
5600	58,26	21,96	37,69	5950	54,88	18,93	34,49

Let's slightly transform the table so that we can operate with both absolute and relative values:

rpm	consumption, l\h Yamaha 50	consumption, l\h Yamaha F50	difference in consumption, %
1000	1,89	1,51	25,00
1500	3,41	2,27	50,00
2000	4,54	3,79	20,00
2500	6,44	4,92	30,77
3000	7,95	6,81	16,67
3500	9,46	6,81	38,89
4000	10,98	8,71	26,09
4500	11,73	10,60	10,71
5000	16,28	13,25	22,86
5500	21,58	17,79	21,28

The RPM range from planing to ~5000 is preferred by the navigator who doesn't like to drag at half throttle, but doesn't intend to spend too much either. Golden mean. And in this range, the four-stroke, as you can calculate, consumes an average of 20.27% less than its two-stroke counterpart. In absolute terms, this savings will be approximately 2.65 l/h. By this amount, the F50 will consume less gasoline, operating in the optimal speed mode.

Let's count the money now. I will make a reservation right away, I do not take into account oil for 2 tons and oil and 2 filters for F50. The introduction of these variables into the calculation will not greatly affect final result, but for F50, in this case, you will have to build a whole function graph.

So, consider gasoline. At the time of writing, the cost of the "participants" of the test was as follows: Yamaha 50HETOL - 346,000 rubles, Yamaha F50HETL - 423,000 rubles. A four-stroke costs 77,000 rubles. more expensive, but it saves gas.

So, we decide to bet on savings. Let's calculate when our "investments" will simply return to us for a start.

As already mentioned, for this pair of engines, gasoline savings are ~ 2.65 l / h in favor of the F50. The cost of the 92nd gasoline at the time of this writing is ~ 36 rubles / l. Let's convert liters into money: 2.65X36 \u003d 95.4. Thus, the average savings in rubles per hour will be 95.4 rubles.

Let's calculate how many hours we need to use the saved gasoline to return the money overpaid for a four-stroke engine:

77000:95,4=807,1.

807 engine hours! Do you feel the scope? That is how much F50 should work so that the overpayment upon purchase, in comparison with 50 2 tons, is completely returned to your pocket.

What is 807 m/h? I think you will not object that there are few people who roll more than 50 hours per season. And this is still quite optimistic - personally, I haven’t been gaining 40 lately ... We count the seasons: 807:50 = 16.14. Think about this figure: 16 years! So much time must pass for the difference in the cost of the pair of motors in question to pay off.

And it's an economical motor!?

I'll tell the truth about you such that it's worse than any lie

See what happens. We came to the store to buy a 50 hp motor. Having heard the manager's tales about a quiet, economical motor, we take "four cycles" instead of two. Those. from a light, dynamic motor, we refuse in favor of a heavier and more expensive motor. The main thing is that it consumes 20% less gasoline. Here it is, marketing in action.

Jokes, jokes, but this is how decisions are often made. The buyer of the forums read a lot, then the seller of the songs sang - and that's it, "the client is ripe."

Let's answer simple questions.

Is it more profitable for a motor manufacturer to sell which motor - simple and cheap or complex and expensive? Of course expensive!

Which motor has more parts: a simple 2-stroke or a more complex one? In difficult. Where is the most likely to break? In difficult. Is it profitable for the manufacturer to sell spare parts for repairs? Yes!

Another very interest Ask: why do most 2-stroke engines in terms of design look like awkward guests from the last century, like some kind of ugly ducklings, and all four-stroke engines are almost ultra-design? What, “kopeck pieces” cannot at least make normal caps? It's not clear, at least not clear.

Well, and finally, to the dealer and everyone he feeds, which one is more profitable for you to sell an expensive or not very expensive motor?

And who benefits from the "4-stroke" philosophy? Answer: it is beneficial for everyone in the chain from the manufacturer to the cashier, but, alas, not for you.

conclusions

The four-stroke is sometimes preferred for some uses, and sometimes is the only alternative. For example, for known types of fishing at low speeds, a 4-stroke engine is more suitable (although there is something to argue about). For constant many hours of movement on the water, whether it is a pensioner who does not care to do more in life, or a fisherman who fishes for days, from last ice to the first - these people may also find 4 measures more convenient. And, of course, we shouldn't forget about professional passenger carriers - that's who care about both resource and savings.

But what will "four strokes" give to an ordinary poor motorboat, resting on the river on a serene, quiet weekend, having a watercraft designed for engines of 30-60 hp? Nothing but a feeling of lightening the pocket from extra money. No matter how stylish and prestigious the “economical-expensive” purchase looks on the transom.

Thus, the choice of a 4-stroke outboard motor for small seasonal runs, if it is much more expensive than a 2-stroke of the same power, looks unprofitable and irrational. At least for those who count money.

In order to answer this question, you need to figure out what a 2-stroke engine is, where it is used and what are the advantages and disadvantages over a 4-stroke one.

Let's start in order. 2-stroke engine - variation piston engine, in which the work process is completed in two piston strokes. Such an engine has only 2 strokes, a compression stroke and a power stroke. Moreover, cleaning and filling the cylinder with a combustible mixture is carried out not by separate cycles, as in a 4-stroke engine, but by joint ones. In this case, the number of piston strokes in a two-stroke engine is greater.

Consider the principle of operation of a 2-stroke engine.

1. Compression stroke.

1.1 Piston movement from piston bottom dead center (BDC) to top dead piston point (TDC). In this case, the piston closes, first the inlet window, then the outlet.

1.2 After that, the compression of the working mixture begins. At the same time, a vacuum is created in the crank chamber, under the piston, under the action of which a combustible mixture enters the crank chamber through the inlet window.

2. Stroke stroke.

2.1 When the piston reaches TDC, the mixture is ignited by a spark from the spark plug.

2.2 Under the action of high pressure, the piston moves from TDC to BDC, while the expanding gases do useful work.

2.3 As the piston descends, it creates high pressure in the crank chamber, the valve closes, thus preventing combustible mixture back into the intake manifold.

2.4 When the piston passes the exhaust port, it will open and the exhaust gases will be released into the atmosphere.

2.5 With further movement, the piston opens the inlet window and the combustible mixture compressed in the crank chamber enters through the channel, filling the cylinder and purging it from exhaust gas residues.

For a more complete picture, consider a video taken from the youtube site:

Consider the main advantages and disadvantages of 2-stroke engines:

Lack of lubrication and gas distribution systems, which significantly reduces the size of the engine;

Simplicity and cheapness in production and manufacture;

Light weight and compact.

The disadvantages are:

Greater fuel consumption than 4-stroke engines;

More noise;

Less durability. But this is a moot point.

Two-stroke engines are used: garden equipment(lawn mowers, trimmers, chainsaws, etc.), also in mopeds, scooters, some motorcycles, go-karts and gasoline generators, etc.

The choice of oil for 2-stroke equipment should be approached very carefully. Like any motor oils, they must be selected according to the tolerances given by equipment manufacturers. To understand this, you need to know how these motor oils are classified.

Consider the classification by API.

Motor oils for two-stroke engines are also classified according to JASO:

From right choice oil depends on how long the equipment will last. Choose quality and reliable products. All Eurol products meet the stated standard and are thoroughly tested in the laboratory. By choosing Eurol products, you choose quality!

Modern cars differ not only in brands and fuel used. There is also a difference in the type of engine. The proposed publication will introduce readers in detail to two-stroke and four-stroke power units.

What every motorist needs to know about the operation of the engine

It should be noted that any modern vehicle is a complex system of interconnected mechanisms. Like the human body, in which the work of all organs depends on a healthy heart, the normal functioning of the car is ensured by a serviceable engine.

To clearly understand the difference two-stroke engine from a four-stroke, first you should familiarize yourself with the principle of operation of a normally functioning mechanism. Its main purpose is to create a certain effort, forcing crankshaft make rotational movements.

The normal operating cycle of a serviceable internal combustion engine is represented by several stages:

1. The internal space of the cylinder is filled with a combustible mixture;
2. Fuel diluted with some air is compressed;
3. Certain conditions cause the mixture to ignite;
4. The heated gases expand and leave the interior of the cylinder.

In a properly functioning power unit, the piston makes translational movements going up and going down. His actions are accompanied by a full period of rotation crankshaft. The movement of the piston in one specific direction is called a stroke.

In one of them, the burnt gases expand, performing useful work. The described process is called the working stroke of the piston. Separately, it should be noted that a full revolution of the crankshaft takes place over two cycles.

Regarding the topic itself this publication, then a two-stroke power unit is called a power unit that performs a working cycle during one period of rotation of the crankshaft, consisting of two cycles.

Two full revolutions of the crankshaft, performed over four strokes, are characteristic of another type of engine called a four-stroke. To determine what the difference between the considered motors is, it is necessary to study in detail the principle of their operation.

Details on the operation of a four-stroke power unit

Let us consider in more detail the principle of operation of a four-stroke motor. In it, every second period of rotation of the crankshaft is accompanied by the ignition of the fuel-air mixture. A special camshaft, sequentially pressing on the rocker arms, alternately opens the intake and exhaust valves. A special spring returns the valve to its original position, closing it.

It is necessary to ensure sufficiently tight contact of the valves with the cylinder head. This will prevent unwanted loss of compression.

So, the principle of operation of the four-stroke power unit represented by four steps:

1. First, the piston is lowered from top position to the bottom dead center, accompanied by opening by a cam mechanism camshaft inlet valve. The inner space of the cylinder is filled with a mixture of fuel and air;
2. The piston begins to rise in the opposite direction, from the bottom position to the top. The process is accompanied by compression of the fuel with a significant increase in its temperature;
3. Performance useful work carried out by combustible gases that guide the piston to the bottom dead center. Their formation occurs as a result of combustion fuel mixture, ignited by a spark from a spark plug that occurs at the final stage of compression;
4. This is followed by the release, represented by extrusion by the piston exhaust gases from inner space cylinder, accompanied by the opening of the exhaust valve. It closes at top dead center. Then the described process is repeated.

The principle of operation of a two-stroke power unit

The supply of a mixture of air and fuel in a two-stroke engine is combined with the process of its compression, and the removal of exhaust gases occurs simultaneously with their expansion. In other words, the working cycle is represented by only two cycles and is carried out in one period of rotation of the crankshaft.

When the piston is raised in the direction from the lower point to the upper one, a special purge window is first blocked, supplying the combustible mixture to the cylinder. When the exhaust port is closed, which contributes to the release of exhaust gases, the process of compressing the fuel mixed with air begins. Due to the vacuum that occurs in the crank chamber, the next portion of the combustible mixture is supplied from the carburetor.

The gases formed after the combustion of fuel, ignited by a spark of a candle at the top dead center of the piston stroke, force it to go down. The crankshaft begins to rotate, doing useful work.

Due to the implementation of the stroke, the pressure inside the crank chamber increases. The mixture of fuel with air, delivered there at the previous stage, is subjected to compression. The piston rises up to the outlet, opening it. Exhaust gases leave the chamber, entering the muffler. The continued movement of the piston contributes to the opening of the purge window.

Thanks to high blood pressure the air-fuel mixture from the crank chamber fills the interior of the cylinder. At the same time, the remnants of exhaust gases are displaced, and the over-piston space is filled. When the piston reaches its lowest position, the cyclic process resumes.

Design differences

From the principle of operation of the two types of engines discussed above, it can be determined how a two-stroke and a four-stroke power unit differ. The main difference lies in design features mechanisms.

The fundamental difference is in the gas exchange system, which supplies the engine with an air-fuel mixture and is responsible for removing exhaust gases from the interior of the cylinders.

Carries out the process due to a special gas distribution device, supplemented by a special valve mechanism. Feeding and discharging are carried out during separate cycles. This somewhat complicates the design of the power unit.

Two-stroke engines are much simpler. In them, the compression and expansion strokes are combined with the filling and emptying of the cylinders. The valve system has been replaced by two special holes in the walls, through which the fuel-air mixture is supplied to the chamber and exhaust gases are removed. The absence of a gas distribution mechanism not only greatly simplifies the design of the power unit, but also significantly reduces its weight.

Comparative analysis of two-stroke and four-stroke motors

To better understand how the types of power units under consideration differ, you should familiarize yourself with their main characteristics, presented in the form of a table.

Four stroke engine	Two stroke engine
The number of piston strokes per full revolution of the crankshaft
2	1
Work balance
Compensate for vibrations caused by uneven torque distribution with a heavy flywheel	The motor runs fairly evenly, allowing a much lighter flywheel to be used.
Engine weight
Heavy due to additional equipment	Much easier
Design
Quite complicated due to the need to use a gas distribution device with a valve mechanism	Simplified due to the absence of a valve system
Price
high	Lower than four stroke
Mechanical efficiency
Reduced due to the large number of rubbing parts	High by reducing the number of moving parts subject to friction
Performance
High, explained by the complete replacement of exhaust gases with a fresh fuel-air mixture	Slightly lower due to the mixing of exhaust gases with a new portion of the combustible mixture
Working temperature
Low	Higher
Cooling
liquid	Air
Fuel consumption
Downgraded by complete combustion	Overestimated due to new injection mixing with exhaust gas residues
Dimensions
Such an engine has big sizes	Two-stroke motors tend to be smaller
Lubrication system
Complex	Simplified
Sound characteristics
Relatively quiet operation	More noisy
Lubricant consumption
Low	Increased
Thermal efficiency
high	Reduced
susceptibility to wear
Friction parts wear out less, which extends the life of the power unit	Faster wear of moving parts contributes to a reduction in the life of the motor

Some positions of the given table require detailed consideration.

The lubrication system of the considered engine models

The principle of lubrication is another significant difference that characterizes the operation of two-stroke and four-stroke models of power units. The first of these involves mixing a certain amount engine oil with gasoline. There are established proportions of such a mixture.

Most often, one part of oil accounts for 25 to 50 parts of gasoline. When a combustible mixture ignites, the lubricant, presented in the form of the smallest atomized particles, burns together with the fuel. Substances resulting from combustion are removed together with the exhaust gases.

There are two ways to obtain an oil-gasoline mixture:

• conventional mechanical mixing with direct fuel supply to the fuel tank;
• All necessary components supplied separately to the system. A special pipe is designed to obtain the required fuel-oil mixture. The part is located in the space separating the cylinder from the carburetor.

For a four-stroke engine, only separate supply of gasoline and oil is used. The fuel does not mix with the lubricant, independently performing the prescribed functions. Therefore, the design of the engine is somewhat complicated due to the need for a separate system that supplies the power unit with the required amount of oil. Additional equipment for lubrication is an oil tank, filter, pump, valves and pipeline.

The requirements for the oil used for two-stroke engines are being tightened due to its complete combustion. A prerequisite is the minimum amount of combustion products in the form of soot and soot.

The lubrication of a four-stroke engine is required to provide stable performance over a long period of operation.

Scope of application

Separately, it should be noted that in terms of efficiency, a four-stroke engine is somewhat more profitable than a two-stroke engine. This is due to reduced fuel consumption, which is important at the current cost of fuel. Despite this, significant dimensions make it possible to use such equipment only for large equipment, like trucks and cars, buses, etc.

The small dimensions, supplemented by the reduced weight of the unit, allow the use of two-stroke engines for mopeds, scooters, motorcycles and other small-sized devices. This motor model is also used in lawn mowers, motor boats etc.

Conclusion

The study made it possible to determine the advantages and disadvantages of the two types of engines. Despite the undeniable advantages of the two stroke motors, they still lose somewhat to four-strokes due to exhaust toxicity and extremely noisy operation.

However, enterprising manufacturers have found a way to offset these annoying shortcomings. Slightly more complex design additional equipment, they suggest using clean air to purge the motor. This innovation will significantly increase the efficiency of a two-stroke power unit along with environmental friendliness.

When choosing power equipment, it is necessary to pay attention to Special attention engine type. There are two types of engines internal combustion: 2-stroke and 4-stroke.

The principle of operation of an internal combustion engine is based on the use of such properties of gases as expansion when heated, which is carried out due to the forced ignition of a combustible mixture injected into the air space of the cylinder.

You can often hear that a 4-stroke engine is better, but to understand why, you need to take a closer look at the principles of operation of each.

The main parts of an internal combustion engine, regardless of its type, are the crank and gas distribution mechanisms, as well as systems responsible for cooling, power, ignition and lubrication of parts.

The transfer of useful work of the expanding gas is carried out through crank mechanism, and the gas distribution mechanism is responsible for the timely injection of the fuel mixture into the cylinder.

Four-stroke engines - Honda's choice

Four-stroke engines are economical, while their work is accompanied by more low level noise, and the exhaust does not contain a combustible mixture and is much more environmentally friendly than a two-stroke engine. That is why Honda company in the manufacture of power equipment uses only four-stroke engines. Honda has been introducing its four-stroke engines to the power market for many years and has achieved highest results, while their quality and reliability have never been questioned. But still, let's look at the principle of operation of 2 and 4 stroke engines.

The principle of operation of a two-stroke engine

The duty cycle of a 2-stroke engine consists of two stages: compression and power stroke.

Compression. The main piston positions are top dead center (TDC) and bottom dead center (BDC). Moving from BDC to TDC, the piston alternately closes first the purge and then the exhaust port, after which the gas in the cylinder begins to compress. At the same time, a fresh combustible mixture enters the crank chamber through the inlet window, which will be used in subsequent compression.

working stroke. After the combustible mixture is compressed as much as possible, it is ignited by an electric spark generated by a candle. At the same time, the temperature of the gas mixture rises sharply and the volume of the gas grows rapidly, exerting a pressure at which the piston begins to move towards the BDC. As the piston descends, it opens the exhaust port, while the combustion products of the combustible mixture are released into the atmosphere. Further movement The piston compresses the fresh combustible mixture and opens the purge port through which the combustible mixture enters the combustion chamber.

The main disadvantage of a two-stroke engine is high flow fuel, and part of the fuel does not have time to benefit. This is due to the presence of a moment at which the purge and outlet openings are simultaneously open, which leads to a partial release of the combustible mixture into the atmosphere. There is also a constant oil consumption, since 2-stroke engines run on a mixture of gasoline and oil. Another inconvenience is the need to constantly prepare the fuel mixture. The main advantages of a two-stroke engine remain its smaller size and weight compared to a 4-stroke counterpart, but the size of power equipment allows you to use 4-stroke engines on them and experience much less hassle during operation. So the lot of 2-stroke engines is left to various modeling, in particular, aircraft modeling, where even an extra 100g matters.

The principle of operation of a four-stroke engine

The operation of a four-stroke engine is significantly different from that of a two-stroke engine. The working cycle of a four-stroke engine consists of four stages: intake, compression, power stroke and exhaust, which is made possible by the use of a valve system.

During the entry stage piston moves down inlet valve, and a combustible mixture enters the cylinder cavity, which, when mixed with the remnants of the used mixture, forms a working mixture.

When compressed the piston moves from BDC to TDC, both valves are closed. The higher the piston rises, the higher the pressure and temperature working mixture.

working stroke four-stroke engine is forced movement piston from TDC to BDC due to the action of a sharply expanding working mixture, ignited by a spark from a candle. As soon as the piston reaches BDC, it opens Exhaust valve.

During graduation The combustion products displaced by the piston moving from BDC to TDC are released into the atmosphere through the exhaust valve.

Due to the use of a valve system, four-stroke internal combustion engines are more economical and environmentally friendly - after all, the emission of unused fuel mixture is eliminated. In operation, they are much quieter than 2-stroke counterparts, and much easier to operate, because they work on a regular AI-92, which you fill your car with. There is no need for constant preparation of a mixture of oil and gasoline, because the oil in these engines is poured separately into oil sump which greatly reduces its consumption. That is why Honda only produces 4-stroke engines and has achieved tremendous success in their production.

The internal combustion engine operates according to a long-studied principle. Worth a closer look at the work piston motor, since rotary and other unusual devices that convert combustion energy into kinetic energy are less common. What is the main difference between a 2-stroke engine and a 4-stroke engine? The most important difference lies in the mode of ignition of the combustible mixture, which can be easily understood by the reproduction of sounds. A two-stroke motor in most cases reproduces a piercing, and also quite loud noise, while in the four-bar there is a more calm and measured sound.

The principle of operation of a 2-stroke engine

1. Most often, the difference is also mainly in the purpose of the device and its overall fuel efficiency. In the engine push-pull type the ignition process is reproduced with each revolution of the crankshaft, it is for this reason that in terms of power they are several times superior to four-stroke ones, in which there are special blend, going mainly through revolutions.
2. Four stroke motors much harder and spend nai large quantity energy. In most cases, they are used on cars and special equipment, while on other equipment such as scooters, lawn mowers, and light varieties of boats, in most cases, you can see more compact two-stroke varieties of devices.
3. And here gasoline generator, for example, you can easily find both two-stroke and four-stroke varieties. The engine in a scooter can also contain absolutely any engine. The principle of operation of such equipment mainly includes the same processes, the difference will be only in the method and efficiency of the overall energy conversion.

What does tact mean?

The process of fuel processing in both models of engines can occur by sequentially performing all four varieties processes, which are otherwise called cycles. The speed at which it is made main job engine passes through three cycles - this is exactly what the main difference between a two-stroke engine and a four-stroke engine is.

The first stroke is the injection. At this time, the piston begins to make a movement following the example of a cylinder, and the intake valve begins to open to let in air-fuel mixture and deliver it to the combustion chamber itself. After that, the combustion process will take place. At this time, the exhaust valve closes back, and the piston continues to move up the cylinder, compressing all the gases that are inside. The stroke of the working stroke occurs when the entire mixture is ignited.

At this time, the spark from the candle begins to replenish all the gases compressed in itself, which provokes an explosion, the energy of which pushes the piston down to its initial position. The last stroke will be considered the release: the piston will reach top point cylinder, and the exhaust valve to open again, allowing all exhaust gases exit the common combustion chamber so that the process can be carried out again. Reciprocating movements in the piston rotate the crankshaft, the torque at this time is transmitted to the working parts in the equipment. This is how the process of converting the energy of fuel combustion into translational motion can take place.

The working process of a four-stroke engine

In a conventional four-stroke device, the ignition of the mixture begins with every second revolution of the shaft. The process of rotating the shaft can result in more complex shaped mechanisms that will help the user achieve successive strokes.

Opening both intake and exhaust valves can occur due to the camshaft, which over and over again presses the rocker arms. The process of returning the valve to the closed initial position is carried out under the influence of a spring. In order not to lose compression, it is worth making sure that the valve begins to fit as tightly as possible to the cylinder head.

How is the process of functioning of a two-stroke device

Now it is worth considering in more detail the process of operation of a two-stroke engine, as well as distinguishing its features from a four-stroke one. In a two-stroke engine, all four actions occur in one revolution of the shaft, during the piston stroke from the top dead center to the bottom, and then up again. The release of excess gases (i.e. purge) and fuel injection are integrated into one cycle, ultimately this process ignites the entire mixture, and the energy received produces a push of the piston down. This arrangement eliminates the particular need for valves in the device itself.

In place of the valves, you can find several openings of the combustion chamber at once. At that moment, when the piston is moved to its lowest point by means of the combustion movement, the exhaust valve will open, allowing all the exhaust gases to be eliminated, by this action the chamber will become completely empty again. During the downward movement, a vacuum is formed in the cylinder, with the help of which a certain mixture of air, as well as additional air, is drawn in through the exhaust valve located in the lower region.

During the upward movement of the piston, it begins to block all channels and is able to compress the gases inside the cylinder. At this time, the spark plug is fired, and after that the whole process described above occurs in a new way. It is important to note that in engines of this format, the process of ignition of the mixture can occur during each subsequent revolution. Which helps to extract more power from them, at least for a certain period of time.

The difference between a two-stroke engine and a four-stroke

Two-stroke motors will be best used in applications that need quick and sharp bursts of all energy, rather than a steady process of operation for a long time. For example, a jet ski accelerates much faster than a simple four-stroke truck. But at the same time needed for short trips, while the truck itself is capable of traveling a distance equal to hundreds of kilometers before it needs to rest.

Short duration of operation push-pull mechanism will be compensated by its low weight to power ratio: these types of engines in most cases weigh much less, it is for this reason that they can start faster and reach the highest indicator of their efficiency, and can also reach the maximum operating temperature. To carry out their movement to another point, a much smaller value of energy is also expended.

What type of motor should you buy?

In most cases four-stroke engines can only work in one position. This may be due to the complexity of the moving mechanisms, as well as the designs of the oil pan.

This type of sump, which provides further lubrication of the engine, is most often found only in four-stroke devices and has the highest importance score for the workflow. A two-stroke engine most often does not have any additional pan, it is for this reason that they can be use in almost any position without the possibility of splashing oily liquid or interruption of equipment lubrication processes. For types of equipment such as chainsaws, circular saws, and other personal tools, this flexibility is considered quite important.

Fuel efficiency as well as value for environment. In most cases, it becomes clear that compact, as well as fast engines in devices pollute the environment much faster and consume a large amount of fuel. At the bottom of the piston movement, when the combustion chamber is completely filled with a combustible mixture, a certain amount of fuel is completely lost, falling into an empty channel.

This can be easily seen if we consider the hanging outboard motor. You can see multi-colored oil stains around it. It is for this reason that engines of this type are considered not very efficient and pollute the surrounding air. And although four-stroke models are heavy and slow in performance, but at the same time they burn fuel completely..

How much does it cost to repair equipment and replace components?

Smaller devices in most cases are considered the cheapest, both in terms of the initial purchase, and in the future. maintenance. But at the same time, they are calculated for a longer operating time. Although there are some out-of-bounds, but most often they are not intended for long service life for more than two hours and are designed for a very short period of use.

The lack of a separated lubrication system can also lead to this. That even in the highest quality motor of this type, wear will occur very quickly, and then it will become unusable due to damage to the moving part.

Partly due to the lack of lubrication in gasoline, which is needed to fill a two-stroke scooter engine, for example, it is worth adding some specialized oil. This can lead to additional costs of time and money, as well as can cause equipment failure(if you ever forget to add a new portion of oil). A four-stroke type motor most often requires minimal care and maintenance from the consumer.

Which motor should you choose

Four-stroke engine main features:

Two stroke engine features:

1. One stroke of the power stroke convenes on every revolution of the crankshaft.
2. A light mechanic should be used and the engine will begin to function quite balanced and measured, since at this time the torque will be distributed much more evenly due to the fact that the ignition process in the combustible mixture will take place during each revolution.
3. The weight of the engine will be much higher.
4. The structure of the engine is presented more simply, due to the absence of a valve mechanism in it.
5. The cost of a two-stroke is noticeably lower.
6. High rate mechanical efficiency due to reduced friction due to the number of parts.
7. Air cooling.
8. High working range.