What Is A Turbocharger?
Very simply, a turbocharger is a kind of air pump taking air at ambient pressures (atmospheric pressure), compressing to a higher pressure and passing the compressed air into the engine via the inlet valves. At the present time, turbos are used mainly on diesel engines, but there is now a move towards the turbo charging of production petrol engines.
As all engines are dependent on air and fuel we know that increase in either of these elements within set limits will increase power from the engine but if we increase the fuel we must be capable of burning off all of it. In order to meet our requirements for power, this requires air; putting in more air presents far more problems than putting in more fuel. Air is around us all the time and is under pressure, (at sea level this pressure is about 15 p.s.i.) It is this pressure that forces air into the cylinders. To increase the air flow, an air pump (turbocharger) is fitted and compressed air is blown into the engine.
This air mixes with the injected fuel allowing the fuel to burn more efficiently so increasing the power output of the engine. One other side of turbocharging, which may be of interest, is an engine which works regularly at high altitudes, where the air is less dense and where turbocharging will restore most of the lost power caused by the drop in air pressure. An engine's power at 8,000 feet is only 75% of its power at sea level.
How Does A Turbocharger Work?
The waste exhaust gases of the engine are utilised to drive a turbine wheel, which is connected to a compressor wheel by a shaft. The compressor or air wheel sucks in air through the air filters and passes this into the engine. As the waste gases are expelled from the engine, they are directed to the turbine or hot wheel of the turbo and so completes the cycle.
Instead of escaping through the exhaust pipe, hot gases produced during combustion flow to the turbocharger. The cylinders inside an internal combustion engine fire in sequence (not all at once), so exhaust exits the combustion chamber in irregular pulses. Conventional single-scroll turbochargers route those irregular pulses of exhaust into the turbine in a way that causes them to collide and interfere with one another, reducing the strength of the flow. In contrast, a twin-scroll turbocharger gathers exhaust from pairs of cylinders in alternating sequence.
The exhaust strikes the turbine blades, spinning them at up to 150,000 rpm. The alternating pulses of exhaust help eliminate turbo lag.
Having served their purpose, exhaust gases flow through an outlet to the catalytic converter, where they are scrubbed of
carbon monoxide, nitrous oxides and other pollutants before exiting through the tailpipe.
Meanwhile, the turbine powers an air compressor, which gathers cold, clean air from a vent and compresses it to 30 percent above atmospheric pressure, or nearly 19 pounds per square inch. Dense, oxygen-rich air flows to the combustion chamber. The additional oxygen makes it possible for the engine to burn gasoline more completely, generating more performance from a smaller engine. As a result, the TwinPower engine generates 30 percent more power than a non-turbocharged one of the same size.
For more info on how a turbo works, you can read more detail in these other pages below.
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