What is a twin-turbo engine?
"Twin turbo" refers to an engine with two turbochargers as the name suggests. This is because two small turbos are more efficient than one large one.
In the low rpm range where there is little exhaust gas, in the case of a single turbo, there is not enough exhaust to turn the turbine. However, by using two small turbos, it is possible to make the most of the characteristics of the turbo even in the low rotation range, as the turbine rotates even with a small amount of exhaust gas.
Imagine blowing into a windmill. In order to turn the windmill vigorously, a small windmill rotates more often than a large one. The twin turbo uses this principle.
This has improved the turbo lag which is the fault of the turbo If you recall, a turbocharged engine is an engine that uses turbine power and forced induction to push extra compressed air into the engine’s combustion chamber. Why? Because this extra air means that extra fuel has to be pushed in as well (to maintain the fuel/air ratio), and you get a boost in power. The extra fuel combusts at a faster rate than a normal engine, so you can put the pedal to the metal.
It means that the Internal Combustion Engine is forcefully inducted with the help of 2 turbochargers.
The naturally aspirated engine, which is what you find in most of the regular cars these days are fitted with toe turbochargers. What they do is suck in air from the exhaust system, passes it through the turbine and into the engine cylinder along with the fuel. When it is passed into the cylinders, the air which was hot is now cold thanks to the inter-cooler. So when cold air-petrol mixture enters the cylinder, combustion takes, but at a better rate thus increasing the power output of the car.
How does a twin turbo engine work?
Typically, in a car, one turbocharger is quite small (very low inertia) and spins up rapidly to reduce turbo lag at low RPM’s. As the RPM’s and exhaust output increase, more and more of the exhaust is directed to the larger turbocharger, which is able to supply a much larger volume of air at the boost the engine was designed for.
What does a twin turbo engine do in your car?
Twin-turbo refers to a turbocharged engine in which two turbochargers compress the intake charge. The most common layout features two identical turbochargers in parallel; other twin-turbo layouts include sequential and staged turbocharging, the latter of which is used in diesel auto racing applications.
The most common twin-turbo configurations
A twin-turbo, on the other hand, is when you actually have TWO turbochargers pushing extra compressed air into the combustion chamber. The turbochargers can be different sizes and can be laid out in different configurations. Here are the three types of setups you’ll typically see:
Parallel
This is when there are two turbochargers of the same size are situated parallel to one another and each turbocharger receives half of the extra exhaust gases. This layout is best suited to V6 and V8 engines because each turbocharger can be assigned to one-cylinder bank and reduce the amount of exhaust piping needed. Parallel twin-turbo engines reduce lag, which can be an issue in turbocharged cars, by using two smaller turbo chargers instead of one large one.
Sequential
Sequential twin-turbo engines utilize one turbocharger for lower speeds and one turbocharger (or sometimes both) for higher speeds. This setup is supposed to offset the issue where turbochargers are unable to provide a boost of power when RPMs are low. Typically, a smaller turbocharger is used for a boost at low speeds and a larger turbocharger is used for a boost at higher speeds.
Series
This type of twin-turbo setup is when the turbochargers are set up in a series. The output from the first one is then further compressed by the second one. This leads to much higher pressure and boost than you’d normally get.