This is an article from Subiesport Magazine, April 2007 on turbo basics. As a noob I always wanted to know this. So for the people scared to ask here it is.
"The first step in improving the beast is to understand the beast. But before you understand the how, you need to know the why. And that why is more power. To make more power, an engine needs two things: fuel and air. To draw more air into cylinders, we need to either increase the size or number of cylinders. In the case of a turbocharged engine, we need to increase the volume of air being pumped into the engine by the turbo.
There are two basics types of turbocharger. One is the type found on your WRX, which uses exhaust energy into a turbine, which in turn powers a compressor. The other main type is typically called a supercharger, which uses a belt driven by the crankcase to power the compressor.
Since Subaru uses exhaust driven turbo, we will concentrate on these. There are three basic parts of a turbo: the compressor (cold side), the center cartridge (CHRA), and the turbine (hot side).
The compressor, as it name implies, compresses intake air. This is the side of the turbo that actually makes the “boost”. The turbine is what powers the turbo. It uses energy from high-pressure exhaust gas to spin at a very high speed. The compressor and the turbine are directly connected by a shaft, which passes thru the center cartridge, which houses the drive shaft bearings and oil and water passages for cooling and lubricating the turbo. The compressor, the turbine and connecting shaft and bearings called the rotating assembly or rotating group. These are the only moving parts in a turbo.
A turbo works by taking ambient air, which is at 14.5 psi (pounds per square inch; also known as “1 bar” or 1 barometric pressure) and compressing it into a denser “charge” of pressurized air. As the turbo compresses air, it also heats this air through friction. To combat this, many turbo systems utilize an intercooler.
The intercooler is a radiator for the intake charge, which brings the pressurized air down in temperature, making it denser and more resistant to knock. The intake charge then enters the intake manifold where it is mixed with fuel, and consequently the combustion chamber, where it ignites.
In turn, this ignition creates pressurized exhaust pulses, which ultimately spin the turbine. As engine load increases so does the amount of energy in the exhaust pulses, which spin the turbo faster, making more boost. It is a very simple system on the surface. Exhaust energy is turned into rotational force, which is then used to compress ambient air and thus pressurize the intake system to make more horsepower.
Simple".
"The first step in improving the beast is to understand the beast. But before you understand the how, you need to know the why. And that why is more power. To make more power, an engine needs two things: fuel and air. To draw more air into cylinders, we need to either increase the size or number of cylinders. In the case of a turbocharged engine, we need to increase the volume of air being pumped into the engine by the turbo.
There are two basics types of turbocharger. One is the type found on your WRX, which uses exhaust energy into a turbine, which in turn powers a compressor. The other main type is typically called a supercharger, which uses a belt driven by the crankcase to power the compressor.
Since Subaru uses exhaust driven turbo, we will concentrate on these. There are three basic parts of a turbo: the compressor (cold side), the center cartridge (CHRA), and the turbine (hot side).
The compressor, as it name implies, compresses intake air. This is the side of the turbo that actually makes the “boost”. The turbine is what powers the turbo. It uses energy from high-pressure exhaust gas to spin at a very high speed. The compressor and the turbine are directly connected by a shaft, which passes thru the center cartridge, which houses the drive shaft bearings and oil and water passages for cooling and lubricating the turbo. The compressor, the turbine and connecting shaft and bearings called the rotating assembly or rotating group. These are the only moving parts in a turbo.
A turbo works by taking ambient air, which is at 14.5 psi (pounds per square inch; also known as “1 bar” or 1 barometric pressure) and compressing it into a denser “charge” of pressurized air. As the turbo compresses air, it also heats this air through friction. To combat this, many turbo systems utilize an intercooler.
The intercooler is a radiator for the intake charge, which brings the pressurized air down in temperature, making it denser and more resistant to knock. The intake charge then enters the intake manifold where it is mixed with fuel, and consequently the combustion chamber, where it ignites.
In turn, this ignition creates pressurized exhaust pulses, which ultimately spin the turbine. As engine load increases so does the amount of energy in the exhaust pulses, which spin the turbo faster, making more boost. It is a very simple system on the surface. Exhaust energy is turned into rotational force, which is then used to compress ambient air and thus pressurize the intake system to make more horsepower.
Simple".
