How Do Turbochargers Work?

When it comes to your engine, more power is usually better. There are a few ways to increase the speed of your vehicle, such as adding more cylinders to your engine, using a mechanically driven supercharger, or installing a turbocharger. With the aid of a turbocharger, your engine receives an extra kick thanks to the heat energy from your exhaust gases, reducing the amount of waste and enabling your car to go faster than it normally would.


The Turbocharger


If you want to achieve higher speeds, a turbocharger is generally as awesome as the name implies. Essentially, a turbocharger is an air compressor that is driven by the pressure and energy from your engine’s exhaust gases to burn more fuel faster and increase the power of your engine. It consists of two small air fans – the turbine and the compressor – attached to opposite ends of a metal shaft known as the CHRA (centre hub rotating assembly), often with a cooling system situated between them.

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What It Does


A common misconception is that the turbocharger itself is providing the additional power somehow. In fact, the source of that increased strength is your vehicle’s own fuel supply, as the turbocharger simply enables a larger amount of fuel to be burned per second in order to give your engine an extra boost.

Although the names are similar, a turbocharger functions differently than a supercharger. Whereas the supercharger draws its power from the crankshaft, the turbocharger runs off a turbine that is driven by the waste energy from exhaust gases. Rather than emitting the excess gases in a thick cloud of exhaust fumes as you’re barreling down the road, this enhancement uses that waste energy in a more environmentally friendly manner to help deliver greater power to the engine.


How It Works


When expanded exhaust gases are expelled from the engine cylinders, they drive the turbine wheel as heat energy. Since the turbine and the compressor are connected to same metal shaft, both wheels spin at the same time. As the gases continue their journey, the exhaust gases are expelled out the exhaust pipe and fresh air is drawn from the air cleaner by the compressor wheel, into the compressor housing. The resulting compressed, pressurized air is sent to the charge air cooler, where it is cooled additionally before entering the intake manifold to create boost pressure, allowing the engine to consume more fuel at a rapid pace.


Welcome to the Wastegate


In order to control the turbocharger’s maximum boost pressure and speed, a wastegate can be installed internally or externally to restrict the flow of exhaust gases passing through the device. The pressure actuator ensures that the set level of boost pressure is consistently maintained by automatically opening the wastegate to release excess exhaust gases when the spring value is exceeded. Since the turbine wheel can’t spin any faster, over-boosting is avoided and, ultimately, the engine is prevented from excessive pressure. This also means that boost is increased in the lower range of RPMs.


Troubleshooting a Turbocharger


Although there are many advantages to using turbochargers on your engine, they add an extra layer of complexity to an already complex mechanism. As such, they require maintenance and troubleshooting to determine the proper course of action if a problem does arise. When correctly installed, turbochargers should not leak oil, but if it happens, you cannot fix the leak by simply replacing the seals, which are generally in a piston ring style. Oil leaks have many different possible causes with many different possible remedies, so it is important to have a professional look at it to determine the cause and the right repairs needed.


Replace or Repair


If you are experiencing a loss of power, turn off the engine and perform the appropriate troubleshooting steps to determine if the turbocharger can be repaired or needs to be replaced. Make sure that nothing is impeding the spinning of the shaft and wheel assembly and that neither the turbine wheel nor the compressor wheel is touching the housing. If it is stiff to turn or the shaft and bearings are not floating on the surface of the oil, you may need a new turbocharger.


Another potential source of turbocharger trouble is the air filter. Keep an eye on it because the engine cannot get enough air if the filter becomes clogged. The exhaust manifold, which is the piping that feeds the turbocharger, should also be examined closely in case it is allowing exhaust gases to escape. If so, this will prevent the turbocharger from achieving its maximum speed, resulting in a low rate of boost to the engine.


Be Preventive and Attentive


To avoid minor issues turning into major headaches, take a proactive approach with a scheduled maintenance program for your engine and turbocharger. There are a variety of reasons these devices fail prematurely, and most of them can be prevented if you pay attention and practice preventive maintenance on a regular basis. For instance, make sure the turbocharger is receiving sufficient lubrication – if not, the rotation of the wheel and shaft assembly becomes unstable and the wheels will make contact with the housing. With repeated rubbing over time, turbocharger failure can occur.


Clear away any debris or other items and objects that could interfere with the operation of the high-speed blades of the compressor and turbine wheels. If the wheels become unbalanced, the instability of the rotation can place extra stress on the bearings and contribute to eventual failure of the turbocharger. Likewise, lubricants containing contaminants can wreak their fair share of havoc when used regularly. These harmful lubricants can cause heavy leakage by damaging the seals, blocking the oil passages, and scoring the shaft’s bearings and journals.


Take Charge of Your Turbocharger


At the same time that it makes your vehicle go faster, the turbocharger may require up to 10 percent less fuel and produce less air pollution because the fuel is being burned with more oxygen than a traditional non-turbo engine. As long as it is carefully installed, correctly operated, and properly maintained, your turbocharger should give you countless hours of fast-paced fun.


Tom Zelinka has been an Alberta Journeyman Automotive Mechanic and Interprovincial Red Seal since 1978. In 1981 he then received his Alberta Journeyman Heavy Duty Mechanic Certificate and Interprovincial Red Seal. He has received Certificates for:  Cummins engine certification on N855/N14/M11 Engines, Cummins B/C/ ISB Series Engines, Cummins B/C/ISB Series Engine Fuel Systems, and Cummins B/C/ISB Series Electronic Engine Controls. Interprovincial CFC/HCFC/HFC certification, Alberta Liquid Petroleum Gas Certification, Alberta Certified Advanced Mobile Hydraulics, Alberta Certified Diesel Engine Control Systems. As the technology and models change, Tom continues to stay on top of the industry to be sure that you are receiving superior service for your Dodge Cummins diesel truck.