1.3 MULTIJET 16V
(75 & 90 HP)
FIAT PUNTO TRAINING OUTLINE
Fiat Auto S.p.A.
After Sales Training
Purpose of a turboblower
The purpose of a turboblower is to achieve very high torque values and, therefore, greater
engine performance. All of this can be obtained by compressing the sucked air. Thanks to the
greater density at every intake phase, a greater amount of oxygen can be let into the engine’s
combustion chamber. The greater oxygen content improves combustion and, as a result,
increases power.
The thermal and kinetic energy of the engine’s exhaust gas is best used to actuate the
turboblower exhaust-gas turbine: the latter actuates the compressor which compresses the
sucked air by heating it. Then, the air is cooled again in the intercooler.
Operation
At low speeds, the turboblower’s distributor blades are actuated electrically and positioned (i)
by vacuum in such a way that the exhaust gas flow hits the outer edge of the turbine blades.
This causes the exhaust gas flow to be restricted and involves increasing exhaust gas flow
speed and boosting pressure. According to the principle of the lever, all of this involves a
higher torque at low speeds.
If the engine revs number increases, the exhaust gas inlet section will be increased by
displacing the distributor blades (II). Now the gas particles will not preferably hit the outer edge
of the distributor blades any longer: they will be found along the entire length of the blades.
The turboblower will operate less efficiently, which will however be compensated for by the
greater exhaust gas volume at high engine speeds.
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If, however, the engine’s maximum power is required (e.g. when overtaking), the electro-
pneumatically operated blades will be displaced to the low speed position, which will
significantly enhance the turbine performance and, as a result, the boosting pressure, thus
making the engine’s maximum power available.
