How much do you know about engine turbocharging technology?

Advantage of original parts 1 – Enhance power and save fuel

Unlike passenger cars, the truck field does not deliberately emphasize that power is a turbocharged engine or a naturally aspirated engine, with turbocharging in almost all vehicle diesel engines. Turbocharging, which is now commonly used, was a rare configuration in the last century. Only in 1953 did Garret apply turbocharging technology to automotive diesel engines. After the 1960s, European and American automotive diesel engines began to use turbochargers extensively.

In the last century, Japanese trucks came to black on a road with naturally aspirated engines. Isuzu Truck has launched more than V8, V10 and V12 large displacement naturally aspirated engines with a maximum displacement of 22.8 litres. The enormous displacement did not allow the engine to burst into super power, with a maximum power of only 450 HP and a low torque output.

Contemporary European trucks chose a small displacement plus turbocharging route, during which European truck manufacturers such as Renault, Volvo, Duff and Iveco prided themselves on the use of turbocharging technology, identically labeled “Turbo” or “Intercooler” in prominent body positions. Iveco went even further by naming a heavy card directly TruboStar, which shows the status of turbocharging in the European minds.

With turbocharging technology, European truck engines are completely superior to Japanese naturally aspirated engines in terms of power. For example, the Volvo D12D engine with turbocharging technology has a maximum torque of 2000 Nm and a displacement of only 12.1 litres for the 420 horsepower version.

The 430 horsepower version of Mitsubishi 8M21-3 naturally aspirated engine with similar power output has a torque of only 1519Nm and a displacement of 21 litres. For the Japanese naturally aspirated engine, the old drivers have a simple and comprehensive evaluation: “doing nothing”. It means that the engine has high fuel consumption, but does not have strong power.

Larger displacement does not bring stronger power performance, which is the disadvantage of naturally aspirated engine. After entering the millennium, due to fuel consumption and emission pressure, Japanese truck engines also began to turn to turbocharging technology and gave up the development of naturally aspirated engines.

Advantages of original parts 2 – high cost performance to solve the problems of engine emissions and fuel consumption

There is no complicated classification of diesel engine supercharger for trucks, such as mechanical turbocharging and composite turbocharging. Without exception, exhaust gas turbocharging is selected, that is, the exhaust gas from the engine is used as the power source to drive the turbine to run without additional consumption of engine power.

Exhaust gas turbocharging can be subdivided into WGT and VNT. WGT is the exhaust bypass gate turbocharger,

VNT, also known as VGT, is a variable cross-section turbocharger. The early diesel engines were almost all WGT. From the working principle of exhaust gas turbocharging, it can be seen that the turbocharging effect can only be achieved when the exhaust gas discharged from the engine reaches a certain level. When the engine is at low speed, the turbine speed is also very low, and the turbocharging effect is weak. This phenomenon is called “turbine hysteresis”.

In actual use, the truck has a heavy load, the engine speed is not high when starting and climbing, and the turbine lag greatly reduces the engine power performance. Diesel engine and truck manufacturers are looking for ways to optimize turbine hysteresis and improve engine low-speed torque output performance. To be familiar, Dongfeng Tianlong’s DCI engine turbocharger is equipped with an auxiliary drive device, which introduces compressed air from the air reservoir to assist in driving the turbocharger blade rotation, and improves the supercharging effect of the turbocharger at low engine speed.

In addition to the auxiliary drive to improve the turbine hysteresis, it is also a way to fundamentally change the turbocharger structure. VNT variable cross-section technology was born to improve the pain point of turbine hysteresis. Garrett took the lead in inventing and mass producing diesel VNT variable cross-section technology more than ten years ago. Its principle is to adjust the air intake volume through a set of movable turbine guide vanes, and close it at low engine speed to increase the intake pressure of the engine and improve the response speed of the engine in low torque range.

With the improvement of emission upgrading standards, the visibility of variable cross-section turbocharging on the 6th national engine is getting higher and higher. On the one hand, it is to improve the efficiency of the engine, on the other hand, it is also related to emissions. According to Eric Fraysse, President of Garrett Ball After-sales Business, “Turbocharging itself is a cost-effective solution to emissions, fuel consumption and power performance.”

The reason is very simple. The better the effect of the supercharger, the higher the fuel economy of the engine, which helps to save energy and reduce emissions. Compared with WGT, VNT technology also has the advantage of variable flow. It can flexibly adjust the differential pressure of the engine inlet and exhaust, meet the demand for the optimal EGR rate of the engine under all operating conditions, and effectively reduce the nitrogen oxide emissions. Under regeneration conditions, VNT supercharger can also help the engine achieve thermal management, reduce fuel consumption by 2% – 3% under regeneration conditions, reduce fuel consumption and reduce the risk of oil dilution.

Post time: Feb-06-2023