Dynamics of a Turbocharger

.....Turbochargers, increase engine power output due to the turbo's ability to compress air that goes into the engine combustion chambers. A turbo’s internal components do not have a mechanical connection with the engine. Hot exhaust gases exiting the cylinders cause the turbine blade to spin. Since exhaust gases are a waste product, the energy produced by the turbo is said to be free. Below are the typical components of a turbocharger.

1. Turbine-Hot
2. Compressor-Cold
3. Waste gate (valve)
4. Cartridge (CHRA) Contains compressor seal assembly, turbine seal assembly, bearings, shaft, oil or coolant passages.
5. Actuator (to control waste gate)

.....Typically a turbo is located on the exhaust manifold, but some are placed further down the exhaust stream. When hot exhaust gases enter the turbine housing they are expelled out of the turbo by means of an exhaust pipe, commonly referred to as a downpipe. On the other side of the turbocharger (cold side) is a compressor wheel that draws in air through a pipe which is usually connected to your air filter which compresses the atmospheric gases. Inside the turbo, the turbine wheel is connected to a shaft that is attached via the compressor wheel. The turbine wheel and compressor wheel are contained in a spiral shaped housing that directs exhaust flow from one side, and compressed air on the other side. The shaft that connects the two wheels rides on bearings to prevent seizing.

.....A turbo's ability to compress air can begin as low as 1600 rpm. The turbine wheel begins to spin when the force of the hot exhaust gases are directed through the exhaust housing side of the turbo. As these gases come into contact with the turbine wheel, the fins (think of a pin wheel) direct gases towards the center of the housing. This action is referred to as vortex flow. Since the compressor wheel is connected to the turbine wheel, it also begins to spin. This action causes air to be drawn into the compressor wheel and housing. From the compressor housing, the air exits under pressure into the cylinders. Now that the intake stream is pressurized, the cylinders are being compressed with air instead of atmospheric pressure filling the vacuum the pistons create. For example - sea level atmospheric pressure is 14.7 psi (pounds per square inch), and the turbo is developing 15 psi. As a result air is being fed into the cylinders at 29.7 psi. As every motorhead knows, more air, more fuel, more POWER.

Happy Boostin'
Court Shanken

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