Royal Mechanical Engineering

Variable geometry turbocharger s ( VGT s) are a family of turbochargers, usually designed to allow the effective aspect ratio (sometimes called A/R Ratio) of the turbo to be altered as conditions change. This is done because optimum aspect ratio at low engine speeds is very different from that at high engine speeds. If the aspect ratio is too large, the turbo will fail to create boost at low speeds; if the aspect ratio is too small, the turbo will choke the engine at high speeds, leading to high exhaust manifold pressures, high pumping losses, and ultimately lower power output. By altering the geometry of the turbine housing as the engine accelerates, the turbo’s aspect ratio can be maintained at its optimum. Because of this, VGTs have a minimal amount of lag, have a low boost threshold, and are very efficient at higher engine speeds. VGTs do not require a waste gate. Most common designs The two most common implementations include a ring of aero...

  A turbocharger is actually a type of supercharger. Originally, the turbocharger was called a "turbo super charger." Obviously, the name was shortened out of convenience. A turbocharger’s purpose is to compress the oxygen entering a car’s engine, increasing the amount of oxygen that enters and thereby increasing the power output. Unlike the belt-driven supercharger that is normally thought of when one hears the word "supercharger," the turbocharger is powered by the car’s own exhaust gases. In other words, a turbocharger takes a by-product of the engine that would otherwise be useless, and uses it to increase the car’s horsepower. Cars without a turbocharger or supercharger are called normally aspirated . Normally aspirated cars draw air into the engine through an air filter; the air then passes through a meter, which monitors and regulates the amount of air that enters the system. The air is then delivered to the engine’s comb...