Why does a turbocharged car consume more fuel than a naturally aspirated car? How much more?

Turbocharged engines consume more fuel than naturally aspirated engines? This question is a bit puzzling. If it is the same displacement engine, such as 1.4T engine and 1.4L engine, it can be clearly found that the fuel consumption of 1.4T engine is higher than that of 1.4L engine. The main reason is that the engine displacement is certain, but the turbocharged engine relies on exhaust gas to drive the turbine to rotate, and the turbine drives the coaxial impeller, which makes the intake air of the engine increase exponentially. The intake air of turbocharged engine is very large, which leads to a large amount of fuel injection. So the fuel consumption of turbocharged engines is normal.

However, compared with the self-priming engine, the power characteristics of the turbocharged engine are really better than a little. Taking Volkswagen engine as an example, the maximum torque of 1.4T turbocharged engine reaches 250Nm, which is widely matched with LaVida, sagitar, Bora, Ling Du and Magotan. The torque value of Volkswagen 1.4 self-priming engine is only 132Nm, so the engine torque value is very low, and such a low torque can also match the entry-level compact car Jetta, so the vehicle power system is very fleshy. Most car owners can only be overtaken when driving this car, and they can never overtake other people's cars.

As far as the turbocharged engine is concerned, the displacement of 1.4T is equivalent to that of 2.4L engine, but the fuel consumption of the engine is equivalent to that of 1.6L self-priming engine. Moreover, at present, the speed of turbine engine is very low, and when the vehicle is at a very low speed, it can still generate a lot of energy in generate. At present, when the speed of turbocharged engine reaches 1500 rpm, the engine can reach the highest torque value. Therefore, the turbocharged engine accelerates very quickly, and the turbine intervention feeling is very small when driving at low speed. The owner will not feel the phenomenon of the turbocharged engine starting meat, and the starting smoothness is obviously improved!

Therefore, compared with self-priming engine, the fuel consumption of turbocharged engine is only based on the same displacement, but under the same power, turbocharged engine is more fuel-efficient than self-priming engine.

First of all, it is certain that 1.8T naturally aspirated engine consumes more fuel than 2.0 naturally aspirated engine under "general road conditions", but this is unreasonable. It is reasonable that 1.8T can reach the power level of 2.4L or 2.8L naturally aspirated engines, so as to compare their fuel consumption.

Outside the "general road conditions", for example, in the case of traffic jam in the city, if the vehicle speed does not reach 30km/h, then the fuel consumption of 1.8T on this section of the road may be lower than that of 2.0 naturally aspirated engine, because the turbocharger does not work until the speed reaches, which is equivalent to a naturally aspirated engine of 1.8L, and it does not work under high load.

Why do turbocharged cars consume more fuel than naturally aspirated cars? How much more fuel will be consumed?

Now there are fewer and fewer naturally aspirated engines on the market. It can be seen that the advantages of turbocharged engine are more and more obvious, and it is more and more in line with the current environmental protection requirements.

In fact, turbocharged engine is not a very advanced technology. It uses the exhaust gas of the engine to drive the turbine to increase the air intake to achieve the purpose of improving power. A supercharger can obviously improve the power of a car with the same displacement. Now the requirements of environmental protection law are more and more strict, and there are more restrictions on the displacement of cars. Therefore, major manufacturers are also trying to reduce the displacement of cars, but the power will be poor after reducing the displacement, so turbochargers are used more and more.

Although the power performance of turbocharged engine will be better, its ride comfort will be relatively poor, especially some turbocharged engines with small displacement, which have many limitations. The low-speed confrontation is obvious, and the high-speed dynamic performance is also average.

Turbocharger is driven by automobile exhaust, which will not obviously increase the fuel consumption of the automobile. In fact, the use of turbocharged engines can reduce the fuel consumption of cars. Why do you say that? Because after adding the supercharger, the speed at which the car can reach the maximum torque will be lower. For example, when driving at high speed, the speed of the turbocharged engine will be lower, so the fuel consumption of the car will be better.

Now the turbocharging technology is very mature. Personally, I think the turbocharged engine is ok. Especially in the case of high performance requirements for automobiles, turbocharged engines have more advantages. If the driving quality and ride comfort of the car are high, you can choose a naturally aspirated engine. If the engine budget is sufficient, try to choose a naturally aspirated engine with a large displacement, and the power output is smooth, which is still very good.

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There is a debate about turbocharged engines and naturally aspirated engines. Whether on the Internet or in the word-of-mouth of consumers, turbocharged engines will save more fuel than naturally aspirated engines, especially after small-displacement turbines become more and more popular, the concept of more fuel-efficient turbines is widely spread.

Not much to say, let's talk about rumors first: compared with engines with the same displacement and number of cylinders, turbocharged engines are not necessarily more fuel-efficient than naturally aspirated engines, or even more fuel-efficient!

The first thing we should understand is that the original intention of designing a turbocharged engine is not to make the engine more fuel efficient.

The appearance of turbocharging technology is to make the engine give full play to its due performance and extract the maximum power output of the engine under as limited a condition as possible. Therefore, from the design purpose of turbocharging technology alone, the argument that "turbocharged engines must save fuel" can basically be taken away by half.

Of course, if we just throw out an explanation of the original design intention, we can't prove the point of view of an automobile hot review, and we need more technical data to support it.

You can't say that this statement is completely wrong, but at least there are some mistakes.

People who have this argument think that natural aspiration runs smoothly, while turbocharging is more passionate; The highest torque of natural inhalation can only be reflected at high speed, while turbocharging can output strong torque at low speed and so on. From these arguments, naturally aspirated and turbocharged seem to be really antagonistic, but if we want to draw the conclusion that naturally aspirated engines consume oil from this antagonistic argument, turbocharged engines are very one-sided.

In response to this statement, a car critic wanted to say that this is not entirely a matter of turbocharging technology, because the key points that determine whether a car saves fuel are its displacement and the thermal efficiency of the engine. To put it more directly, it is whether the engine manufacturing technology of car companies is more advanced.

For example, Volkswagen's EA2 1 1 turbocharged engine, such as Honda's 1.5T Earth Dream engine, such as Mazda's Chuangchi Blue Sky engine and so on.

Compared with their previous engines, these engines have more advanced fuel injection control technology, fuel combustion technology, gas distribution system circulation technology, cylinder compression technology and so on. These technologies can further improve the thermal efficiency of fuel, and they are the key to make turbocharged engines more fuel-efficient, rather than the car will become more fuel-efficient immediately after you install a turbocharger on a naturally aspirated engine.

Therefore, a car hot review believes that this view must be corrected, especially when buying a car, and must not be blinded by the promotion of turbocharging by merchants.

Turbocharged engine, after reaching a certain speed point, the pressure reducing valve begins to release pressure, the air compressor starts to run at full load, and a large amount of air will be forced into the engine cylinder, so the intake air of turbocharged engine will be larger. If the fuel injection quantity of the two engines is the same at this time, the content of hot air in the oil-gas concentration of the turbocharged engine will be higher, and for engine ignition, the mixture concentration of oil and gas is too thin or too high, which is not conducive to the smooth ignition of combustible gas.

Under the above assumptions, when the naturally aspirated engine successfully reaches the appropriate ignition concentration of the air-fuel mixture, the air-fuel mixture concentration of the turbocharged engine will be lean, and the thermal efficiency of the turbocharged engine will be low in this case. Then, in order to achieve better thermal efficiency, the turbocharged engine must inject more fuel, so as to make its air-fuel mixture concentration reach normal.

At this time, we can see that the thermal efficiency of turbocharged engine will be lower under the assumed conditions, and it will not save fuel.

As mentioned earlier, the key to determining whether a car saves fuel is two points: displacement and thermal efficiency.

Then the small-displacement turbocharged engine naturally has a certain fuel-saving advantage because of its small displacement, but if there is a car hot comment that the small-displacement turbocharged engine is not as fuel-efficient as you think, do you believe it?

This has to mention the working characteristics of turbocharged engines!

Of the four strokes of a four-stroke engine, only one does work, that is, the power stroke, also called the ignition stroke, but which stroke causes the combustible oil-gas mixture to produce high pressure and high temperature in the cylinder?

Yes, the compression stroke!

Friends who know about turbocharged engines should know that turbocharged engines have a bad characteristic, that is, their "knocking" problem. Due to the high ambient temperature when the turbocharged engine works, the compressed combustible mixture will be in a high temperature and high pressure state when the piston runs to the top dead center of the cylinder during the compression stroke of the engine.

If the high temperature and high pressure environment at that time is enough to ignite gasoline in a certain compression stroke, the combustible mixture will spontaneously ignite locally before the spark plug is ignited. At this time, if the spark plug starts to ignite, the ignited other mixed gases will form another ignition source. Under the superposition of shock waves of energy explosion of two ignition sources, the energy explosion of fuel will bring impact force to the cylinder wall, thus forming knocking.

In fact, there are many solutions, such as delaying the ignition time of spark plugs and reducing the compression ratio of engines. If we carefully observe the compression ratio of turbocharged engines, they are indeed lower than naturally aspirated engines, which is why. However, these methods will weaken the dynamic performance of small-displacement turbocharged engines, so engineers have come up with another trick: using the endothermic principle of liquid in the gasification process to cool the high temperature and high pressure gas in the compression stroke.

So how did you do it?

It's actually quite simple. Before the ignition of the spark plug and the compression stroke reach the top dead center, the fuel is injected first, so that part of the fuel begins to vaporize in advance. At this time, the vaporized fuel will take away part of the heat formed in the compression stroke, which avoids the problem of spontaneous combustion of the mixture due to high temperature and also ensures the dynamic performance of the small displacement turbocharged engine.

So knowledge is power. Who said that the knowledge taught in junior high school textbooks will be useless when they grow up?

As for the data of the Ministry of Industry and Information Technology, it cannot be said that their data are inaccurate.

However, the working condition of the Ministry of Industry and Information Technology is similar to NEDC in Europe, which is a test method consisting of urban operation cycle and suburban operation cycle, while the test of the Ministry of Industry and Information Technology is closer to the fuel consumption state when driving at a constant speed in urban areas, but lacks the performance of high-speed driving, and the test conditions basically do not consider wind resistance factors.

Therefore, many of our SUVs with large wind resistance can often measure quite good fuel consumption results in the test of the Ministry of Industry and Information Technology, but after consumers actually buy them, you will find that the fuel consumption is actually not low, which is why.

To sum up, the above hot comments only demonstrate that a turbocharged engine may not be more fuel-efficient than a naturally aspirated engine under the same displacement, but a turbocharged engine will be more fuel-efficient under the same engine technology, so don't casually say that "buying a turbocharged engine will save fuel".

As for the fact that turbocharged engines are more fuel-efficient than naturally aspirated engines, I won't write much because of limited space, otherwise it will become a novel. Readers only need to remember this conclusion: "Under the same power output and the same technology as other engines, turbocharged engines will save more fuel than naturally aspirated engines."

See how to compare! Under the premise of the same power level, turbocharging is more fuel-efficient than natural inhalation; However, under the premise of the same displacement level, turbocharging consumes more oil than natural inhalation. After all, a turbine mechanism was added to increase the self-weight. More importantly, increasing the turbine back pressure will increase the pumping power and fuel consumption of the engine. Comparing the fuel consumption of self-priming and turbocharging with the same displacement, it is inevitable that turbocharging costs oil, but turbocharging with the same displacement can provide higher power output, which self-priming does not have.

Imagine: You usually eat one steamed bun every day. Today, you doubled your usual workload and ate two steamed buns at once. Turbocharging is the principle. If you eat more, you will do more. Here steamed bread is fuel consumption, and your workload is the power output of the engine.

But in reality, we generally don't compare the self-priming with the same displacement with the fuel consumption of the turbine. Because turbocharging will inevitably consume engine oil, we will compare turbocharging with natural inhalation at the same power level, that is, since everyone can output almost the same power level, whoever has low fuel consumption will definitely have an advantage. For example, the mainstream 2.0T four-cylinder power is basically at the same level as that of 3.0V6, and the performance version of 2.0T is even comparable to that of 3.5L. Obviously, the fuel consumption of 2.0T will be much lower than that of 3.0L and 3.5L (there is little difference in engine technology).

Back to the question: it is common sense that turbocharging with the same displacement consumes more oil than natural inhalation, just like 1+ 1 = 2, which is not meaningful for discussion. Of course, you should not compare the fuel consumption of 2.0L self-priming 20 years ago with that of 2.0T now. Let's just explain the problem and talk about the similar situation of additional factors (carrier technology, technical level, car company training). Those who push the bar can go out and turn right.

How much higher will the fuel consumption be? There is no way to find exactly the same engine, only the difference between supercharged and non-supercharged engines, so only reasoning+theory+practice can get a more reasonable reference. How to speculate?

At present, small inertia turbocharger is widely used in small displacement turbocharging of family cars. Considering the displacement, stability, fuel economy and other factors, the boosting intensity of small inertia turbocharger is generally 0.4-0.5bar, which is less than half atmospheric pressure. If the supercharging intensity is too large, it will adversely affect the engine hardware, fuel standard and combustion stability. Supercharging intensity is also a dynamic process with speed and load. According to the supercharging intensity with a peak value of 0.5bar, the single cylinder air intake of the engine under a certain working load can be regarded as: single cylinder displacement × 1.5. For example, the air intake of the engine in a working cycle with a supercharging intensity of 0.5bar is 1.5T, which can be simply regarded as (easy to understand, roughly estimated) 1.5 ×. The simple understanding is that thermal efficiency and mechanical loss are the same, which is equivalent to the fuel consumption of a 2.25L self-priming engine after excluding all influencing factors. Because the engine's control of air-fuel ratio has been fluctuating around the theoretical air-fuel ratio, how much air is taken in and how much oil is burned is certain. Therefore, it is a fundamental reason that the turbine with the same displacement consumes more fuel than the self-priming turbine. Because there is more air to burn, more fuel must be injected. If the fuel consumption is compared from the combustion intake, it can almost be understood as an increase of 1.5 times, which is a multiple of the turbocharging intensity.

However, the actual situation is that turbocharging often adopts more efficient, more accurate and advanced high-pressure direct injection and mixed injection, as well as more fuel-efficient stratified combustion, lean combustion and other advanced technologies. Turbocharging will optimize the shape of cylinder block, cylinder, air passage, piston and cooling and lubrication system. After these columns are optimized, the fuel consumption increase of the same displacement turbocharging will be less than 50%. As for how small it is, it depends on the hardware and training technology of each OEM. However, from some technical data published by Volkswagen and Toyota, it can be seen that these optimizations will reduce the fuel consumption of the engine by about 5%-8% compared with direct injection and self-priming, and save about 10%- 15% compared with EFI and self-priming.

First, turbocharging costs oil. Although fuel consumption can be reduced through various technical optimization, fuel consumption is still higher than self-priming. However, there is another reason why major manufacturers pursue turbocharging to save fuel: turbocharging can make the engine enter the high efficiency area of the engine ahead of time or earlier, and expand the common working conditions of the engine to the high efficiency working conditions. At this time, the compression ratio of the engine increases, the resistance, mechanical and pumping losses are small, and the efficiency of converting fuel into power is high, thus achieving the purpose of saving fuel. But how much can this save? Combined with double VVT of air intake and exhaust, the fuel consumption can be saved by about 5%- 15%. If you stay in the high thermal efficiency range for a long time, the fuel saving effect will be more obvious, reaching about 20%. If the fuel-saving effects of the first point and the second point are calculated theoretically, the fuel consumption of turbocharged engine will be about 20%-40% higher than that of naturally aspirated engine with the same displacement, that is, the fuel consumption of engine in the high thermal efficiency range will be about 1.5T and 1.5L higher than that of the above example, and it will be about 15% higher in other working conditions. So you will find that in some cases (elevated roads, highways, etc. ), 1.5L can run 6 oils, and 1.5T can also run within 7 oils. Similarly, in some cases (congested road sections), 1.5 L can run 9 oils, while 1.5T can also run 1-65438.

Turbocharging increases the intake air, and the volume of each cylinder is fixed, so more fuel needs to be injected to consume the air. This situation is equivalent to increasing the intake air and increasing the engine load under the same throttle opening. Because of the characteristics of internal combustion engine under load, the engine tends to run with high efficiency. This situation is obvious under low, medium and high loads, and the fuel saving effect of the turbine is also obvious. In addition, the miniaturization advantage of turbocharging is obvious, especially compared with naturally aspirated engines of the same power level.

To sum up, turbocharging with the same displacement costs more oil than natural inhalation, and the specific cost can only be speculated. According to different working conditions, the fuel consumption is often about 20%-40% higher. In comprehensive working conditions, the fuel consumption of small inertia turbocharging will be about 30% higher than that of self-priming with the same displacement, but the power provided by turbocharging with the same displacement is rolling natural inhalation. Turbocharging has advantages and disadvantages, but generally speaking, the advantages outweigh the disadvantages, so it is also the reason why turbines are rampant today.

For the fuel consumption of turbocharged and naturally aspirated, we only need to remember two words:

Turbocharged engines with the same displacement definitely have higher fuel consumption than naturally aspirated engines, and turbocharged engines with the same power definitely have lower fuel consumption than naturally aspirated engines! Of course, the above comparison is based on the premise of similar technology. A naturally aspirated engine 30 years ago can't compare with the turbocharged engine now.

The air-fuel ratio of an engine is the ratio of air to fuel. Under normal circumstances, the ratio is 14.7: 1, which means that it is necessary to inhale 14.7 grams of air and match 1 gram of gasoline. Of course, this ratio is only an ideal air-fuel ratio. In fact, the air-fuel ratio is not constant, generally it will be between 12- 18: 1. Today's engines are all EFI systems. When air enters the combustion chamber from the intake manifold, a certain proportion of gasoline needs to be injected into the fuel nozzle. The EFI system will detect the oxygen content in the engine exhaust through the oxygen sensor. The principle is simple. Too much oxygen means that the mixture is too rich, and too low oxygen means that the mixture is too thin. The ECU of the driving computer of the engine dynamically controls the fuel injection quantity according to the detection value of the oxygen sensor. So as to keep the air-fuel ratio within the correct proportional range. (Engine closed-loop control)

When EFI engine is in cold start, low water temperature and heavy load, the fuel injection quantity cannot be controlled by oxygen sensor. At this time, it is necessary to use the solidified air flow ratio in the driving computer to control the fuel injection quantity (engine open-loop control).

Whether closed-loop control or open-loop control, the main purpose is to maintain the correct air-fuel ratio.

The turbocharger is equivalent to a blower, which mainly plays the role of continuously injecting air into the combustion chamber. When the air pressure increases, the air density will increase. By injecting the same amount of fuel through the EFI system, the purpose of increasing fuel combustion without changing the displacement is achieved, so as to improve the output power of the engine. And increasing power output will naturally consume more oil. In other words, a turbocharged engine with the same displacement will consume more fuel than a naturally aspirated engine. The turbocharging value of a general family car is about 1.5Bar, and the fuel consumption of a turbocharged engine with the same displacement is about 20-40% higher than that of a naturally aspirated engine, and the power will also be increased by 20-40%.

According to the above explanation, we know that the miniaturization of turbocharged engine can achieve small displacement and high power output, that is to say, for the same power output, naturally aspirated engine needs 2.0L displacement, while turbocharged engine only needs1.5l. Due to the miniaturization of engine, the pumping loss and friction resistance of engine are relatively small, which naturally saves fuel consumption.

A prominent feature of turbocharged engine is low torque. According to the conversion formula of power and torque: power P= torque X speed, when the power is constant, the greater the torque, the lower the speed. That is to say, with the same power output, turbocharging may only need 2000 revolutions, while naturally aspirated engines may need at least 3000 revolutions to obtain the same power.

After the engine is supercharged, the optimal power output range can be greatly reduced, and then the engine speed can be controlled at a relatively low speed through the matching of the gearbox. The reduction of speed and the improvement of combustion efficiency will naturally save fuel. According to the universal characteristic curve of the engine, the optimal power output range of the turbocharged engine shifts to a lower speed range, which will naturally save fuel. Generally speaking, the fuel consumption of turbocharged engines with the same power is about 10% lower than that of naturally aspirated engines.

First of all, it is certain that 1.8T naturally aspirated engine consumes more fuel than 2.0 naturally aspirated engine under "general road conditions", but this is unreasonable. It is reasonable that 1.8T can reach the power level of 2.4L or 2.8L naturally aspirated engines, so as to compare their fuel consumption. Outside the "general road conditions", for example, in the case of traffic jam in the city, if the vehicle speed does not reach 30km/h, then the fuel consumption of 1.8T on this section of the road may be lower than that of 2.0 naturally aspirated engine, because the turbocharger does not work until the speed reaches, which is equivalent to a naturally aspirated engine of 1.8L, and it does not work under high load. If you are a dealer, you want to tell your customers that 1.8T consumes more fuel than 2.0. It's unreasonable, but it's true. Generally, if the road is not too congested, it is manual. If 1.8T is above 9L/ 100km, the natural inhalation of 2.0 is 8.7-9L/ 100km, and the difference will not be great. If you buy a car, don't compare the two, first look at what kind of personality you belong to before choosing. Personally, 1.8T is more suitable for energetic and trendy people, with good motivation and high technical content. If it is usually congested, it will save fuel, but it should be noted that the maintenance cost behind it will be high. If the personality is very stable, choose 2.0 to inhale naturally. In the eyes of ordinary people, the displacement is large and the maintenance cost is relatively low.

If the engine displacement is the same, turbocharging is basically more expensive than natural aspiration. But turbocharging with the same displacement in power is much better than natural inhalation! After all, the exhaust gas uses compressed air to make the engine inhale more gas to achieve stronger power, and in order to make the air-fuel ratio normal, it will also inject more fuel. So turbocharging will consume more fuel.

For example, for a 2.0-displacement engine, the fuel consumption of turbocharging is about10-1200 kilometers per liter. Inhale naturally for 7-900 kilometers without rising.

I want you to understand the fuel consumption of the same car, 2.0T and 2.0 self-priming turbines! But 2.0T power is comparable to 3.0 self-priming fuel consumption and 3.0 self-priming fuel consumption! The starting point of car companies is to use 2.0T instead of 3.0 or more displacement to save fuel! I don't want you to misunderstand me.