Turbochargers also improve the fuel efficiency of a vehicle however there is a misconception when it comes to turbocharged vehicles and fuel efficiency. Taking a naturally aspirated engine and slapping on a turbocharger on it will not improve fuel efficiency. The way that manufacturers improve fuel efficiency though turbocharging is by down-sizing an engine and then turbocharging it. For example, take a 2.5L inline-4 cylinder naturally aspirated engine and decrease the displacement to 1.4L and then turbocharger it. The smaller, turbocharged engine would still have the same performance figures (or slightly better) but because of the smaller displacement, it would also use less fuel.
In automotive applications, "boost" refers to the amount by which intake manifold pressure exceeds atmospheric pressure at sea level. This is representative of the extra air pressure that is achieved over what would be achieved without the forced induction. The level of boost may be shown on a pressure gauge, usually in bar, psi or possibly kPa. The control of turbocharger boost has changed dramatically over the 100-plus years of their use. Modern turbochargers can use wastegates, blow-off valves and variable geometry, as discussed in later sections.
In petrol engine turbocharger applications, boost pressure is limited to keep the entire engine system, including the turbocharger, inside its thermal and mechanical design operating range. Over-boosting an engine frequently causes damage to the engine in a variety of ways including pre-ignition, overheating, and over-stressing the engine's internal hardware. For example, to avoid engine knocking (also known as detonation) and the related physical damage to the engine, the intake manifold pressure must not get too high, thus the pressure at the intake manifold of the engine must be controlled by some means. Opening the wastegate allows the excess energy destined for the turbine to bypass it and pass directly to the exhaust pipe, thus reducing boost pressure. The wastegate can be either controlled manually (frequently seen in aircraft) or by an actuator (in automotive applications, it is often controlled by the engine control unit).
Therefore, there are many kinds of turbocharger for different types of vehicles like Turbocharger for Audi, Turbocharger for Seat, Turbocharger for Skoda, Turbocharger for Volkswagen, Turbocharger for BMW, Turbocharger for Mercedes-Benz, Turbocharger for Toyota, Turbocharger for Volvo, Turbocharger for Hyundai, etc.