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14.7 Boost control
This auxiliary output configuration allows the driving of a boost pressure control
solenoid. FuelTech recommends using a 3-way N75 solenoid, found in the original 4 and 5-
cylinder VW/Audi Turbo models, which can be directly switched through the auxiliary output.
Such solenoid valve controls the pressure on the top and bottom parts of the
wastegate valve, changing the engine manifold pressure with which the latter opens.
FuelTech does not recommend the use of this solenoid when reaching pressure levels above
36psi, as leakage may occur.
Wastegate
at the exhaust manifold
This type of valve is used on most cars with adapted turbo, in
competitions, etc. With it, the longest connection from the N75 valve is left in open
air, and the upper one is connected to the pressurization. The shortest side
When the N75 is off, it
allows the flow of pressure from
the pressurization to the
Being so, the maximum
pressure allowed by the
wastegate is limited by its
spring.
When activated, the
air, which completely closes the communication between the exhaust
manifold and the wastegate output, and allows the turbine to generate
its maximum pressure, i.e., total pressure. The higher the counter
pressure generated by the turbine at the exhaust manifold, the lower its maximum pressure is.
Wastegate
integrated to the turbine
This valve has a different operation system, as it relieves the boost pressure when pressure is put on its top part, which
is the opposite of what happens to the wastegate installed at the exhaust manifold.
When the N75 is off, the top part of the wastegate receives pressure coming
directly from the pressurization, therefore
letting the turbine generate only as much
pressure as the wastegate spring allows.
When activated, the solenoid alters the
course of the pressure coming from the
pressurization to open air, relieving the
pressure put on the top part of the wastegate,
which completely closes the passage of exhaust
gases and makes the turbine generate
maximum pressure.
Important Note: be very CAUTIOUS when using this resource. When values close to 100% boost have been
programmed, the turbine may generate full pressure, which may cause engine damage if it has not been properly
prepared to support the pressure levels reached.
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