Toyota Supra 1990 TurboCharger System Factory Repair PDF Manual

The turbocharger is a device which increases engine output by sending a greater amount of air-fuel mixture to the engine than under normal conditions. Engine output depends upon the amount of the airfuel mixture ignited per unit of time. Therefore, to increase engine output, the most effective method is to send a greater amount of air-fuel mixture into the cylinder. In other words, by installing a special turbocharger and providing more air-fuel mixture than usual, engine output can be increased by increasing the average combustion pressure without increasing the engine speed. Superchargers are either turbocharger type (supercharging exhaust gas to turn the turbine) or er type (using the engine crankshaft etc., to etc). For the Supra 7M-GTE mechanically the pump, engine, the turbocharger type has been adopted.

Operation of the Turbocharger
Exhaust gas acts on the turbine wheel inside the turbine housing, causing it to revolve. When the turbine revolves, the impeller wheel which is located on the same shaft also revolves, compressing the intake air which has passed through the air flow meter from the air cleaner. When expelled from the compressor housing the compressed air is supplied to the cylinders. When the engine speed increases, the exhaust gas volume increases and the turbine wheel revolutions increase (approx. 20,000 rpm – 1 10,000 rpm), thus the turbocharged air pressure grows greater and engine output increases.

Waste Gate Valve
Although on the one hand high output is achieved by turbocharging, if the turbocharged air pressure becomes too high, knocking occurs and on the contrary, a reduction in engine output is caused. If the turbocharged air pressure exceeds the prescribed air pressure, the flow of exhaust gas bypasses the turbine, controlling turbine wheel revolutions and turbocharge air pressure. This by-pass valve which controls the quantity of exhaust gas flowing to the turbine is called the waste gate valve. When the supercharged air pressure exceeds the prescribed pressure, the actuator operates, the waste gate valve opens and part of the exhaust gas by-passes the turbine. This causes a drop in the turbine revolution rate and controls the supercharged air within the prescribed limits.

Intercooler
The intercooler cools the turbocharged air (intake air) put out by the turbocharger, thereby increasing the air density. As the air intake efficiency increases, the gas temperature in the combustion chamber falls and the occurrence of knocking is suppressed giving an increases engine output.
The Supra 7M-GTE intercooler is an air cooling type located at the front of the vehicle, utilizing the vehicle windstream to cool the turbocharged air.

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