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Ways of letting an engine get
more air for combustion of the fuel
The more air you can get into an engine, the more fuel can be combusted at each pisto cycle and the greater work can the engine do.
Cool air intake systems and air shielding
One principle of achieving a higher air density is to let the air that goes from the outside far away from the motor so that it can be so cold as possible. Cold air contains more mass of oxygen than warm air in each volume unit, so the engine gets more oxygen this way. Usually cool air intake systems let the air in under the grill.
By letting the cold air intake be heading frontwards pointing in the direction the car moves, the speed of the car will also press the air inside with force and compress it, which means that this effect also increae the supply of air to the motor
By shielding the air hoses with an outer coverage you can also hinder the air of getting hot before the entering the motor. Normally a cool intake system will have shields too, but sucj can also be puchased separately.
Multi-valve systems and other ways of widening the air intake to the cylinders
Another principle is to let the air intake be as wide as possible. Thereby the air going into the engine do not get as easily thinned out by resistance and the air pressure is not getting so easily reduced. Also this effect increases the amount of oxygen the motor gets.
But all of the path of the air into the motor most get wider, including the air intake, hoses, manifolds, filters and valve system. Having greater capacity in just one part, while others are narrow, will only gain just a little.
By letting the motor have many or wide valves, the last hinderance for the air to enter the motor is alleviated, allowing more air to get inside.
Also the air intake must be kept clean to secure optimal motor performance. Filters must be cleaned or shifted regularly, and also the whole of the intake system must regularly be rinsed.
Turbochargers and compressors
A third principle is to press the air into the motor by some compressor device, of which the most usual are turbochargers and superchargers (compressors).
Therefore it is possible to inject more fuel for each piston stroke and get the injected fuel more totally consumed. Because of this you can get more power out of the motor or you can drive more economically when you take out a more average power.
Here are some articles that explaining more about devices to get more air into the mortor.
Intercoolers
An intercooler is a heat exchanger mounted after the turbocharger or compressor to take away heat that the compression has produced, which make the air entering into the motor more dense and containing more oxygen per volume unit.
This gives the motor more power, but also protects the motor from overheating.
The intercooler contains several parallel tubes the air goes through, and between the tubes cold air or water is circulated to take away the heat and deliver it to the outside.
One will somtimes use a double compressor with the intercooler mounted in the air flow between the compressors, and another fater the second compressor.
Sometimes one will also use an extra intercooler to cool down air let out from the motor that shall be used to drive a turbocharger.
About turbochargers and compressors (superchargers)
These are units that actively press air into the motor so that compressed air enters the cylinders. Compressed air have a greater pressure and contain more oxygen mass per volume unit. Thereby the motor is able to burn more fuel at each stroke cycle and thereby deliver more work. Turbochargers also enable the moror to work effectively at very high revolution speeds.
Turbochargers and compressors difer in the way they are driven.
A turbocharger is a double turbine unit coupled together. The exhaused from the motor goes through the first turbine and drives this round and thereby also the common pivot of the two turbine units. Th air from the outside goes through the other turbine unit, the compressor, before it enters the motor. This unit presses the air further into the motor.
A turbine that is driven by a fluid is only effective when the pressure from the fluid has a certain lower limit, and a turbin used to pump a fluid is only effective when speed of the rotation is over a certain limit. Therefore a turbocharger tend to have no effect at lower speeds and then the effect sets in quite abruptly when the car reaches a certain speed.
The pressure of the air must however not be too high, because that results in detonation of the blending of fuel and air. By detonation all the blending is combusted abruptly without the flame propagating smoothle inside teh belending.
The working rotational units inside the two turbines are usually radial fans.
To avoid this a wastegate regultes some of the exhaust around the compressor when the speed of the turbocharger reaches a certain limit.
A compressor or supercharger is a turbine driven directly by the rotation of the motor using mechanical couplings like gears and pivots, chains or belts. The air goes through the turbine that presses the air into the motor.
A charger increases the effect of the engine, but it consumes energy to drive the charger. Therefore engines with chargers uses more fuel than without any device to compress the air.