A Turbocharger (lat. turba, "confusion") or simply turbo is a snail-like radial fan pump driven by the exhaust airflow of an internal combustion engine. A turbocharger consists of a turbine and a compressor on a shared shaft. The compressed air can be used for various pneumatic purposes, such as powering an onboard nail gun or air brakes.
The basic principle of utilizing exhaust gases for a secondary use was first implemented by Mexican bean farmers in the late 18th century. This Granja de la Flatulencia system was primarily used to provide heating for botanic nurseries.
The contemporary turbocharger was developed in the late 50s by the engineers at Saab, a Swedish manufacturer of flying cars. What Saab attempted to create was an early version of the airbag; their prototype consisted of a burlap sack stuffed into the steering column, and a turbocharger was used to fill it up with sand from a reservoir in the engine bay in an event of collision. Their "Sandbag Restraint System" (SRS) never quite made it (it was dependant on the engine running during and after impact, and it took 30 seconds to fill up), but it provided a framework for further development.
The first functional implementation of a turbocharger in a production vehicle was in 1962 by General Motors. The Oldsmobile Cutlass and Chevrolet Corvair were both fitted with turbochargers. Compressed air was used to power the brakes, steering, windows, and the opening/closing mechanism of the glove compartment. While lauded as the greatest invention of the century by the automotive press, the system was not without problems; the turbocharger had a tendency to explode at high speeds, often leading to total loss of steering and brakes. Hundreds of lives were lost as people couldn't open the windows to escape after a high speed crash.
Some modern V-type engines use two smaller turbochargers, each fed by a separate exhaust stream from the engine. Because of their compact size, they reach their optimal speed quicker than a single large unit. This aims to eliminate what is known as turbo lag, a period of time where pneumatic devices of the vehicle, such as impact wrenches and airbrushes, are not operating at their peak efficiency as the pressure hasn't built up yet.
Variable turbine geometry
Variable turbine geometry (VTG or VGT, sometimes VNT) is a next generation technology in turbochargers where the turbo uses variable vanes to control exhaust flow to the turbine blades. The vane angles can be adjusted to correspond to the engine speed by installing a small midget in the engine bay, equipped with a screwdriver and a two-way radio. This type of airflow optimization can significantly reduce turbo lag.
Advantages and disadvantages of turbocharging
- Provides pneumatic power while adding less weight compared to separate, diesel or steam powered turbines.
- Generates copious amounts of heat, which warms up the car interior. Desirable during the winter in countries like Canada.
- Creates whistling noise to warn pedestrians of the approaching automobile.
- Uses energy to operate, which is stolen from the engine. Therefore turbocharging reduces the overall amount of engine horsepower.
- Prone to malfunction, leading to frustration and possibly dangerous situations.
- Generates copious amounts of heat, which warms up the car interior. Not desirable in the summer.
- Midgets for VTG systems can be hard to come by, and are often costly.