Turbo Fundamentals :: Subaru Impreza RB5 Owners Club
Introduction
A turbo is a high precision 'air pump', used to supply more air into the engine by harnessing on the usually wasted energy in the engine exhaust.
Principles of Turbo charging
The exhaust gases (dark red arrow) drive the turbine wheel and shaft, which is coupled to the compressor wheel. When the compressor wheel rotates, fresh air (dark blue arrow) is forced-fed at high pressure into the combustion chamber (light blue arrow).
With a high concentration of oxygen per cubic volume and optimum air-fuel ratio, combustion is now cleaner and more complete.
Benefit of Turbo charging
Increases engine output and torque
Lowers diesel fuel consumption
Reduces harmful engine emission
Uses more compact and lighter engines
What is Intercooling
Intercooling is a process whereby an air cooler, called the intercooler, reduces the temperature of the compressed air intake, making it denser with a higher concentration of oxygen per cubic air volume. Coupled with turbo charging, an even higher level of combustion is achieved, thereby releasing an additional 15% engine power.
What is a waste gate
A bypass valve (waste gate/regulator) allows the turbo system to develop peak charge-air pressure for maximum engine boost response while eliminating the chance of excessive manifold pressure (over boost) at high speed.
The waste gate is precisely calibrated and opens to direct some exhaust gas flow around the turbine wheel. This limits shaft speed which in turn control boost pressure.
