A Guide to Variable Geometry Turbocharger

A Guide to Variable Geometry Turbocharger

Variable geometry turbocharger, also known as variable nozzle turbine is a type of motor device that increases the air pressure by compressing it. Regular usage and a detailed study have identified that variable geometry turbocharger has a very minimum or less lags and also has a minimum boost threshold, which helps the engine to perform better. These are generally used in medium-duty and heavy-duty truck engines. The heavy-duty engines and the medium-duty engines are combined with electronically controlled variable geometry turbochargers. These are much better than the older waste gate or the fixed geometry because it provides a much better and smooth engine performance, better braking system, a better and a quick shifting of gears and most importantly, the lesser fuel consumption. It is also widely used in smaller engines to increase the torque rating and for a better horsepower. One of the most important factors is what A/R ratio it has. It is a geometric term and A is an abbreviation for the compressor or the turbine and R is an abbreviation for the radius of the area covered by A. The overall flow capacity hugely relies on how much is the A/R ratio and has a great bearing on the all-around performance of these turbochargers. Here are some tips to maintain such turbochargers.

Understanding the A/R ratio: A much smaller ratio can actually increase the rate of the exhaust gas and when it gets to enter the turbine wheel, it makes the compressor much faster and it provides a rapid increase in the air boost. The only disadvantage of this ratio is that the exhaust gas flows tangent towards the direction of the turbine wheel and decreases the turbocharger’s flow capacity and thus the capacity of the engine to exchange gas decreases.

On the other hand, a larger ratio can drastically increase the turbocharger's flow capacity at very high speeds and also the backpressure in the exhaust gets considerably reduced. Therefore, the capacity of the engine to breathe or exchange gas increases. One main disadvantage of it is that at intermediate and low speeds, the velocity of exhaust gas gets lower so the air boost for intake gets slower as well. Therefore, a well-experienced professional who knows and understands the effect of A/R ratio should handle this sort of cases and situations.

Inspecting and checking: Variable geometry turbochargers can be maintained by properly inspecting and examining the variable geometry actuator and identifying a proper way of the mechanism for the operation. We must do a close inspection and check the axial movement of the shaft and wheels of turbochargers. In addition, we must properly check the radiated movement of the shafts and wheels of the turbocharger

Regular servicing: One thing we must always keep in mind that machines tend to break down after a certain period of time and can give financial issues to the company or its owner. Therefore, proper servicing at regular intervals helps them to run properly and prevents them from getting damaged. Like in the case of VGT, we must always check regularly that the engine oil is changed and the coolant is flushed regularly. We must always do a proper inspection and check whether the exhausts have any sort of leakage or not. In addition, the leakage of air inside the intake system should be thoroughly checked and examined.


Variable Geometry Turbocharger is designed especially for the heavy-duty trucks and lorries. In this busy and fast-moving world, VGT has actually eased down the pressure on the mechanics and has significantly gained everyone's attention.

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