A Turbocharged vehicle converts thermal energy that would be lost in exhaust into engine power. This process can be complicated by an issue known as "turbo-lag," where before turbo takes effect, the car functions as normal, but when it does, the turbo can cause a sudden increase in power, making the car difficult to control. To combat this problem, companies began using twin-turbo models, which utilize two turbochargers instead of one.
General Motors (GM) began producing the first turbocharged passenger models in 1962 with the Chevrolet Corvair and Oldsmobile Jetfire. However, they were unreliable and caused heavy pollution, and soon disappeared from the market.
The most common type of twin-turbo engine is known as parallel turbo, in which two turbochargers run simultaneously, each feeding energy to a single group of cylinders.
In this second type of turbocharged engine, instead of running at the same time, the chargers run in a manner so that at low speeds, only one of the turbochargers is functioning. Then, when the car reaches high enough rotations per minute, the second charger will kick in to bring the turbo to its maximum power. Though this system is more efficient, it is also very complicated to install, and is thus not very popular.
