Necessity of Turbocharger and Supercharger

The turbocharger and supercharger are devices that force air into the cylinders creating a pressure that is greater than the atmospheric pressure in order to increase engine output.
Generally, the engine output is determined by the amount of the air-fuel mixture, burned over a specified period of time, and becomes greater as the amount of the air-fuel mixture increases.
That means in order to increase the engine output, either the engine displacement or engine speed must be increased.
The problem is that as engine displacement increases, engine weight also increases and factors such as friction loss, vibration and noise of moving parts limit the increase of the engine speed. The super charger meets the opposing requirements of increasing engine output while keeping it compact and lightweight by supplying greater volumes of air and fuel without changing engine size.
The devices are driven by two methods: The turbocharger is driven by exhaust gas and the supercharger is driven by the engine. Toyota adopted the turbocharger in 1980, and the supercharger in 1985 in Japan. Presently in 2002, only the turbocharger is used in overseas models.

Features of Turbocharger and Supercharger

Both the turbocharger and supercharger are a kind of air pump, which force the air into the cylinder to increase the mass of the intake air. The conventional engine draws air in, using the vacuum generated when the piston goes down.
The pressure inside the intake manifold becomes higher because the turbocharger or supercharger force the intake air into the cylinders at a pressure (boost pressure) higher than atmospheric pressure. Thus, the mass of the intake air into the cylinder is increased.

Description

The turbocharger is a device which uses the energy of the exhaust gas to rotate the turbine wheel at high speeds. There is a compressor wheel on the same shaft as the turbine wheel which compresses air into the cylinders when it is rotated.
In this way, engine output is increased.

The waste gate valve and actuator prevent the boost pressure from rising too high. Some models are equipped with an intercooler to lower the temperature of the compressed intake air and improve the charging efficiency ratio. NOTICE:
Caution is necessary for handling vehicles because the turbocharger becomes extremely hot due to the exhaust gases.
Also, it is necessary to faithfully replace the engine oil at the determined replacement interval.
Refer to the “Precautions for Turbocharger” for more information.