1.5L REVOTORQ ENGINE 77 COMPONENTS A. Exhaust Manifold The exhaust manifold is mounted on the cylinder head. The exhaust gases are trapped out from the engine through the exhaust manifold. B. Turbocharger (VGT) Compared to traditional turbochargers a Variable Geometry Turbocharger (VGT) has better performance at low engine speeds and a low boost threshold. The geometry of a VGT keeps varying with engine speed to provide optimum boost. Hence even at low engine speeds it is able to produce the required boost. The actuation for geometry change is controlled by the EMS ECU instantaneously and progressively. This gives smooth and better drive ability. The boost control over the entire speed/load is adjusted such that it reduces the vehicle emission. CONSTRUCTION AND FUNCTION The VGT has a set of movable vanes in the turbine housing, and they control the boost. At low engine speeds when exhaust flow is low, the vanes are partially closed. This increases the pressure of the exhaust gases pushing against the turbine blades, making the turbine spin faster and generating more boost. As engine speed increases, so does the exhaust flow, so the vanes are opened to reduce turbine pressure and hold boost steady or reduce it as needed. By reading the manifold pressure sensor, the ECU can adjust turbine inlet pressure (by varying the Geometry of Vanes) instantaneously to control the boost at any speed/ load and to limit boost at full load. ADVANTAGES / FEATURES Good low end torque. Good transient response. Good fuel economy. Increased useful engine operating range. It provides more matching level of pressure boost even to a slow spinning turbine without providing too much of a boost at higher speed. VGT is electronically controlled and pneumatically actuated. Low engine noise. Lower emission. SYSTEM FLOW For system flow schematic refer exhaust system schematic layout. The exhaust gases are made to pass through the turbocharger turbine which will rotate the compressor mounted on the same shaft on the air inlet side. The air from the air filter is sucked by VGT compressor. The compressed air then flows through an intercooler and then to the intake manifold. For more information refer Air intake system. PRECAUTIONS Avoid Lifting the turbocharger by holding the actuator. Avoid Lifting turbocharger holding the rod end. Avoid Lifting turbocharger holding the compressor side. Hold the turbo-charger at the turbine housing /center housing.
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