What is a turbocharger?
Understanding turbochargers starts with the basic principles of engines themselves. Air and fuel with introduced into a closed chamber or cylinder. The mixture is ignited resulting in combustion, which drives a piston connected to a crankshaft— used to deliver rotational force to the wheels that propel the vehicle.
Turbochargers use the exhaust gasses to spin a turbine, powering a compressor fan that forces more air into engine intake. The additional air allows more fuel to be introduced, resulting in bigger combustion.
In Technical Terms:
A turbocharger is a turbine-driven, forced-induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber. This improvement over a naturally aspirated engine’s power output is due to the fact that the compressor can force more air — and proportionately more fuel — into the combustion chamber than atmospheric pressure alone.
Turbochargers introduce two connected air fans into both the engine’s air intake and exhaust systems. Both fans are mounted to common metal shaft, called the CENTER HUB ROTATING ASSEMBLY, so that they both spin together.
On the exhaust side, the fan is called the TURBINE. As the cylinders eject hot gas during the 4th stroke, the flow passes over the turbine causing it to spin. It’s a simple reuse of the energy already produced during combustion, rather than discharging it directly to the atmosphere.
On the intake side, the fan is called the COMPRESSOR. Since it’s connected to the turbine fan on the center hub rotating assembly, it spins with the turbine. The compressor fan is used to force additional air into the engine to produce higher power by allowing for more fuel to be combusted.
A HEAT EXCHANGER is used to cool the compressed air, a byproduct of the process itself.
It’s easy to mistake how turbochargers create more power. The exhaust energy isn’t directly reclaimed to add more power. The additional power comes from the forced air result that the turbocharger delivers. In reality, the exhaust is used to power the turbocharger component only, which isn’t connected to the engine drivetrain at all.