Home History How it Works Physics Multimedia Bibliography
Physics
There is a lot of physics involved in a turbocharger.
moment of Inertia = mass x (radius x radius)
Turbochargers have a significant effect on the acceleration of the car. But the turbo does not compress air right away because it takes time to spin up the turbine, compress the air, and send it to the intake. There is a big lag of power, when the car is accelerating. Inertia plays a big role in this. If the turbo is smaller then it has lower radius and thus lower moment of inertia. Smaller turbos speed up faster and compress the air faster. This reduces the lag and the turbo boosts quicker at lower speeds. A larger turbo has a higher radius of the turbine. This increases the moment of inertia which increases the lag. Even though the there is a lag at low speeds, there is more boost at high speeds. Mass is also important. Some turbos have ceramic turbines to reduce mass and thus reducing the moment of inertia.
Some cars are equipped with two turbochargers, a smaller and a large one. This has a great advantage, because at low speeds the smaller turbo boosts and at higher speeds the larger turbo boosts.
Air pressure
An average turbo boosts about 1.5 kg/cm^2 meaning that at sea level the air pressure going into the engine is about 2.5333 kg/cm^2. The air is less dense when the elevation increases. Regular cars experience loss in power when there altitude increases because the air is less dense. When there is less air then there is less fuel. The mixture entering the combustion chamber has low fuel, therefore less total power. A turbocharged car has better performance in higher elevation. The turbo boosts up the air pressure at high elevations and makes it seem that power is not lost. If the car is driving on roads below sea level the air pressure is very high and with a turbocharger, the car experiences great performance.
Air temperature
When air is cool, there are more oxygen atoms for a given volume. The turbo coolers are designed to cool the air before it gets to the intake. Air being compressed and cool gives the most boost to the power of the car. Many modified cars have a custom air filters that are exposed to colder air. This gets more cold air to the intake. Many turbocharged cars also have a custom air filter that helps preserve more oxygen atoms for the engine. The cold air that enters the air filter is then compressed by the turbo which heats up, is then moved through the turbo cooler and to the engine intake.
Friction
The shaft that runs the turbine and compressor has fluid bearings. Fluid bearings can be replaced by a special type of ball bearings. These ball bearings are "super-precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers." Lower friction helps the shaft rotate with less resistance and decreasing the force to start spinning the shaft.
There is a lot of physics involved in a turbocharger.
moment of Inertia = mass x (radius x radius)
Turbochargers have a significant effect on the acceleration of the car. But the turbo does not compress air right away because it takes time to spin up the turbine, compress the air, and send it to the intake. There is a big lag of power, when the car is accelerating. Inertia plays a big role in this. If the turbo is smaller then it has lower radius and thus lower moment of inertia. Smaller turbos speed up faster and compress the air faster. This reduces the lag and the turbo boosts quicker at lower speeds. A larger turbo has a higher radius of the turbine. This increases the moment of inertia which increases the lag. Even though the there is a lag at low speeds, there is more boost at high speeds. Mass is also important. Some turbos have ceramic turbines to reduce mass and thus reducing the moment of inertia.
Some cars are equipped with two turbochargers, a smaller and a large one. This has a great advantage, because at low speeds the smaller turbo boosts and at higher speeds the larger turbo boosts.
Air pressure
An average turbo boosts about 1.5 kg/cm^2 meaning that at sea level the air pressure going into the engine is about 2.5333 kg/cm^2. The air is less dense when the elevation increases. Regular cars experience loss in power when there altitude increases because the air is less dense. When there is less air then there is less fuel. The mixture entering the combustion chamber has low fuel, therefore less total power. A turbocharged car has better performance in higher elevation. The turbo boosts up the air pressure at high elevations and makes it seem that power is not lost. If the car is driving on roads below sea level the air pressure is very high and with a turbocharger, the car experiences great performance.
Air temperature
When air is cool, there are more oxygen atoms for a given volume. The turbo coolers are designed to cool the air before it gets to the intake. Air being compressed and cool gives the most boost to the power of the car. Many modified cars have a custom air filters that are exposed to colder air. This gets more cold air to the intake. Many turbocharged cars also have a custom air filter that helps preserve more oxygen atoms for the engine. The cold air that enters the air filter is then compressed by the turbo which heats up, is then moved through the turbo cooler and to the engine intake.
Friction
The shaft that runs the turbine and compressor has fluid bearings. Fluid bearings can be replaced by a special type of ball bearings. These ball bearings are "super-precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers." Lower friction helps the shaft rotate with less resistance and decreasing the force to start spinning the shaft.