SAFARI

100

ENGINE2.2LDICOR

Variable Turbin Technology (VTT) uses a variable

nozzle turbine (VNT) - Turbocharger

VariableNozzle Turbine Turbocharger

(Fig. 212)

Traditional turbochargers generate their maximum

boost pressure at high engine speed/load conditions.

At partial loads and at low engine speeds these

turbochargers generate limited boost. This in turn

limits the torque generated by the engine. Over-boost

is prevented with an exhaust bypass or "waste gate"

that limits the exhaust gas energy reaching the turbine

and this boost control is extremely limited.

This turbocharger enables exceptional flexibility in

matching and controlling engine air requirements over

extremely broad speed & load range by

accommodating variable exhaust flow rates.

This results in higher power and torque under all

operating conditions, resulting in excellent

acceleration & driveability under various speed & load

conditions

Higher Power

From low to high engine speeds, the turbocharger with

VTT delivers high a boost pressure with low pumping

losses resulting in higher power throughout engine

speeds.

Higher Torque and ImprovedTransient Response

At low engine speeds, the VTT turbocharger

accelerates more quickly due to lower inertia &

variable multi turbine vanes. This helps in increasing

the available high torque immediately after pressing

the accelerator pedal resulting in very good transient

response.

Lower Fuel ConsumptionandEmissions

A lower engine outlet pressure directly reduces fuel

consumption by reducing engine pumping losses.

Optimized boost pressure control by the engine

management system further improves fuel economy

and reduces emissions throughout the operating

range of the engine.

Construction and Function

The VNT Turbocharger has a set of movable vanes in

the turbine housing, and they control boost. At low

engine speeds when exhaust flow is low, the vanes

are partially closed. This increases the pressure of the

exhaust pushing against the turbine blades, making

the turbine spin faster and generating more boost. As

engine speed increases, so does exhaust flow, so the

vanes are opened to reduce turbine pressure and hold

VariableNozzle TurbineTurbocharger (VNT)

Fig. 212

VNT cross sectional view