How Turbochargers work
A turbocharger is a forced induction compressor. The turbocharger is in fact driven by a turbine powered by the pressure of the engine exhaust gas. All turbochargers are made out of a compressor and a turbine. The turbine’s wheels rotate because of the pressure of the exhaust gases via the turbine’s inlet. The resulted rotation of the wheel drives the compressor which starts to compress air. Optionally, the compressed air can be delivered through an intercooler system to cool it down because hot air degrades the performance of the engine resulting in a loss of power. The air is pumped through the air intake of the engine and because of the high pressure, the cylinder receives more air. So the objective of the turbocharger is to increase the performance of the engine by increasing the quantity of air the cylinders receive. All this additional air that the cylinders receive requires an increase in the amount of fuel being pumped. This means that a turbocharged system will output from 15 to 40 percent more power at high rotations, but at the cost of fuel. The turbocharger has some security features like the wastegate. This wastegate protects the engine from receiving too much at air at high pressure preventing preignition or engine damages. This system works by sending some of the air away from the exhaust turbine and controls the shaft speed.
The turbocharger technology was first tested in aviation and it successfully demonstrated that it can overcome the power losses engines supported at high altitude. At the time, the purpose of the turbocharger was to increase the altitude at which airplanes could fly. The brand new systems managed to compensate the low air pressure present at those altitudes and airplanes could go even higher. The automotive industry used the turbocharger since 1962. The first turbocharged cars were produced by General Motors. An A-body Oldsmobile Cutlass Jetfire is the first car that ever used a supercharger and had a 3.5 liter V8 engine. After realizing the benefits of this system for cars, all of the leading car producers started implementing turbochargers on their engines. Peugeot sold the world’s first production turbo diesel car back in the 1978, the Peugeot 604 Turbodiesel. Nowadays, almost all diesel engines are turbocharged.
The turbocharger boost pressure it the increase in manifold pressure in the intake path. You can see the level of boost on the pressure gauge, indicated in bars, psi, or maybe kPa. This pressure is limited by the wastegate to make sure the engine and turbo are kept in the operating range. The maximum boosts depend on many factors, like the fuel octane rating, the engine design, and the engine predisposition to preignition. If you have a calibrated engine, you should be able to reach high boost pressures. The only problem is that the airflow from the turbocharger is hot, and hot air does not have a good impact on an engine. Because of the high rotations of the turbo (80000-200000 rpm), it uses a fluid bearing. This means that all the moving parts are suspended in and cooled by a flow of oil. If you want to further cool the air form the turbocharger, you should use an intercooler system.
The ability to boost the power without major weight increase made the turbocharger very useful for motorcycles. The first motorcycle to use a turbo is the 1978 Kawasaki Z1R TC. But because of the mounting of the turbocharger, the prices got too big and since 2007 turbocharged motorcycles are not equipped with a turbocharger (unless optional).
Turbochargers can be damaged by dirty oil so manufacturers advise a more frequent oil change schedule. If the turbocharger was used for a short period of time it is advised to leave the engine on for one to three minutes so that the turbo can run at its idle speed and temperature. You can get a turbo timer to help keep the engine working for a small time even if you forget about the turbo. In order to reduce the lag, many producers are mounting two smaller turbochargers (twin turbo). The smaller turbochargers equal a big one in strength but have smaller lag because of the smaller size.
You can use a turbocharger if you want a boost in power of about 15-40%, at the cost of fuel consumption. If you decide to buy a turbocharger, read its technical instructions very carefully to make sure it is fitted for your car.