Mazda Speed 6. Manual — part 4

01 ENGINE

18

Air Ducts and Charge Air Cooler

Air cleaner to turbo inlet (low pressure/low temperature)

Turbo outlet to charge air cooler (high pressure/high
temperature)
Charge air cooler to throttle body/intake manifold (high
pressure/low temperature)

Air bypass valve to turbo inlet

01 ENGINE

19

Turbo

Turbochargers consist of a housing, a blade assembly, inlet ducts for low pressure
air and outlet ducts for high pressure air, an intercooler, oil inlet and return, coolant
inlet and return, and boost control circuits.

The turbine blade is on the exhaust side of the turbocharger and the compressor
blade is on the intake side of the turbocharger. The turbine blade is spun by exhaust
pressure.The compressor blade spins and pressurizes the intake air.

The hot/high pressure air coming out of the turbo is sent to the intercooler to cool it
and make it denser.

The shaft between the turbocharger’s blades rides on bearing surfaces and a thin
fi lm of oil. The turbo’s center upper housing has an oil feed line that connects to the
engines lubrication system to provide pressurized oil. On the bottom of the turbo
housing is an oil drain line to return oil back to the engines crankcase.

Compressed
air to charge
air cooler/
intercooler

Exhaust pressure
to spin turbine from
exhaust manifold

Air from air
cleaner

Out to
exhaust

01 ENGINE

20

Turbocharger Inlet and Outlet Pressures and Temperatures

Waste Gate
Solenoid

Exhaust to spin the
turbine

High pressure hot air
to intercooler

Low pressure
air from air
cleaner

Exhaust bypassing
turbine when the
waste gate opens

Compressor
blade

Turbine
blade

01 ENGINE

21

Waste Gate
The waste gate is a valve that allows exhaust pressure to bypass the turbocharger
turbine and dump directly into the exhaust. The waste gate valve actuator controls
the waste gate. When the waste gate opens, the turbine spins slower.

Waste Gate Actuator
The waste gate actuator consists of a control rod connected to the waste gate valve
and a spring and diaphragm that hold the waste gate valve closed. The actuator
pops open to allow the exhaust to bypass the turbocharger turbine and dump directly
into the exhaust.

Waste gate
valve open

Spring
and
diaphragm

Waste Gate
Actuator Rod