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Find videos and animations on the Cummins Turbo Technologies YouTube Channel, which show how a turbocharger works

Critical to the Operation of Diesel Engines

An engine is designed to burn a fuel-air mixture to produce mechanical energy. The mechanical energy then moves pistons up and down to create the rotary motion that turns the wheels of a vehicle. The more mechanical energy, the more power the engine can produce. A significant difference between a turbocharged diesel engine and a traditional naturally aspirated gasoline engine is that the air entering a diesel engine is compressed before the fuel is injected. This is where the turbocharger is critical to the power output and efficiency of the diesel engine. It is the job of the turbocharger to compress more air flowing into the engine’s cylinder. When air is compressed the oxygen molecules are packed closer together. This increase in air means that more fuel can be added for the same size naturally aspirated engine. This generates increased mechanical power and overall efficiency improvement of the combustion process. Therefore, the engine size can be reduced for a turbocharged engine leading to better packaging, weight saving benefits and overall improved fuel economy. Although turbocharging is a relatively simple concept, the turbocharger is critical to the operation of the diesel engine and therefore requires a highly engineered component. Our extensive experience in turbocharging technology and knowledge of engines combines for world-class design and manufacture of Holset Turbochargers, renowned for their durability, high standard of safety, and reliable performance that engines demand.

How does a turbocharger work?

A turbocharger is made up of two main sections: the turbine and the compressor. The turbine consists of the (1) turbine wheel and the (2) turbine housing. It is the job of the turbine housing to guide the (3) exhaust gas into the turbine wheel. The energy from the exhaust gas turns the turbine wheel, and the gas then exits the turbine housing through an (4) exhaust outlet area.

(1) The turbine wheel
(2) The turbine housing
(3) Exhaust gas
(4) Exhaust outlet area
(5) The compressor wheel
(6) The compressor housing
(7) Forged steel shaft
(8) Compressed air

The compressor also consists of two parts: the (5) compressor wheel and the (6) compressor housing. The compressor’s mode of action is opposite that of the turbine. The compressor wheel is attached to the turbine by a (7) forged steel shaft, and as the turbine turns the compressor wheel, the high-velocity spinning draws in air and compresses it. The compressor housing then converts the high-velocity, low-pressure air stream into a high-pressure, low-velocity air stream through a process called diffusion. The (8) compressed air is pushed into the engine, allowing the engine to burn more fuel to produce more power.

Did you know? The exhaust gas passing through the turbine can be up to760°C /1400°F. For ovens that would be Gas Mark 46! The compressor can compress the air to a pressure 50 times higher than you can generate with your lungs. The turbocharger's shaft can transmit around 100 horsepower, enough to power a small family car, despite being only 1cm in diameter. The turbocharger has to survive high vibration forces on the engine. It can survive acceleration forces up to 20g (4 times higher than a rollercoaster). Our small turbochargers can operate at 200,000rpm – they go round more than three times every millisecond!