Exhaust Turbocharging

Because it increases the mass of air inducted, exhaust turbocharging boosts a Diesel engine's power output significantly over that with natural aspiration, with little increase in dimensions, weight and rotational speed. At the same time, the brake horsepower can be increased corresponding to the increase in air mass. In addition, specific fuel consumption can often be decreased.
With an exhaust turbocharger, the engine's exhaust is not simply released to the atmosphere. Its energy is utilized to drive the turbocharger's turbine at rotational speeds up to 100,000 rpm. In turn, by means of a shaft, the turbine drives a compressor, which draws in air, compresses it, and delivers it to the engine under pressure. Not just the pressure, but also the temperature of the air is raised; if the temperature increase is too great, some form of intercooling between turbocharger and engine intake is needed.