Forced Induction  Forced Induction is a term normally associated with Turbo's and Superchargers Engines. The main aim of these devices is to increase engine power, engine efficiency and some times emissions with minimal engine redesign and normally small weight gains. Normally a set amount of fuel will yield a maximum amount of power, to increase power more fuel will need to be burnt in the engine. As a engine can normally only take in a set amount of air at normal atmospheric pressure, to raise power the air intake needs to be increased. Strengths and weaknesses vary depending on the type of forced Induction application used and the desired aims and goals trying to be achieved. But essentially the aim for both of these devices is to compress the air to higher then atmospheric levels, resulting in a higher Oxygen levels. Superchargers
Superchargers can come in a number of different designs and are mechanical driven units. These can be Belt, Direct Drive, Gear Drive, Chain Drive and Electrical Drive driven systems. Essentially by using a certain amount of power to drive a compressor, gains in power can be achieved with minimum weight gains compared to increasing the size of the engine. Also adding a Supercharger is more straight forward then a Turbocharger installation due to no engineering work needed to the exhaust system. Also service maintenance for these units are less extensive.Instant throttle response and the most cost effective increase in power are achieved with these units. Also the Supercharger used will need engine power to actually run, for instants a standard 100 Bhp engine might produce 150 Bhp with a Supercharger installation. But the Supercharger might consume 25 Bhp to run, reducing in a Net 25Bhp gain.This results in higher fuel consumption and will only be effective where throttle response and power are the main considerations. Drag racing is a good example. There are two types of units used commonly in most production cars Centrifugal and Positive Displacement Superchargers. Positve Displacement Superchargers  Positive Displacement Superchargers different from Centrifugal set ups, by delivering a more broad power distribution across the entire Engine Rev range. With the majority in the lower to Mid range engine Rev range. Using engine torque generated from the rotational mass of the internal crank pulley to drive the Supercharger mechanically, in turn this is connected to a air compressor.
Due to the fact a Supercharger is directly linked to the engine, power gains can be achieved through out the usable RPM range. Positive Displacement Supercharger will yield more efficiency lower down the Rev range. Centrifugal Superchargers  Centrifugal Superchargers provide power gains by increasing volumetric air intake to more then atmospheric pressure. With more compressed air entering the combustion chamber, more fuel can be added resulting in a increase in engine power.
This type of Supercharger will result in more boost and power gains higher up in the engines Rpm range, resulting with maximum power at the top of the Rev range. Little to no power gains are likely to happen lower down the engine Rev range, so careful usage application will be required.
Fuel efficiency is not affected as much as in a Positive Displacement application, due to the fact the unit doesn't come into effect until higher in the power band. Turbochargers 
A turbocharger relies on the volume and velocity of exhaust gases to spool, or spin the turbine wheel and this is effectively more power being produced from otherwise wasted exhaust gases. The higher the gas flow, the more the air is compressed and larger power gains are achieved. Maximum Turbo power can be achieved lower down the Engine Rpm range and depending on boost pressure, huge power gains are possible, The technology has proven Motorsport application both in F1 and WRC, with origins coming from the Aeronautical Industry. In the early automotive applications, huge Turbo lag was apparent (the time it takes for the unit to start accelerating). With the use of advance ECU's and anti lag set ups, this is becoming a thing of the past. 
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