The basic function of both superchargers and turbochargers is to deliver more air to an engine’s internal combustion process. Superchargers are mechanically powered often by connection to the engine crankshaft while turbos are powered by engine exhaust gas.
How do superchargers work?
The supercharger type sits on top of the air intake manifold. A serpentine belt transfers crankshaft power to the supercharger’s pulley. Pulley diameter and construction is an easily accessible way to quickly alter. Supercharger performance characteristics a gear drive system delivers incoming power to opposing rotors. Outside air enters through the air filter and intake pipe. Interlocking rotors force air through the supercharger the long fins or ridges that span the length of the rotor shaft are called lobes. Air exists the supercharger through a specially shaped discharge port at the bottom of the housing.
Roots: The roots-type supercharger saw its first automobile application in 1900.
Blower: The term blower or blown engine originates from the root supercharger’s basic function as an air blower as opposed to other designs that compress air.
Twin screw: The twin-screw type superchargers feature complex rotors with intricately designed lobes that compress air as it moves through the unit. This increased complexity results in better performance but also high manufacturing costs.
Centrifugal: Centrifugal superchargers have much in common with the turbo design concept though they are still mechanically driven. They produce an exponential power curve and are often tuned to make a full boost at the engine redline.
- Superchargers have instant power the second you match your foot to the floor.
- Since superchargers are belt-driven they rob horsepower from the engine to allow you to turn this pulley while a supercharger is a giver and a taker. They also make a cool noise.
- The immediate response of the instant power comes at a cost which is efficiency.
- Superchargers add more stress to an engine’s internal components, which can lead to increased wear and tear and decreased reliability over time.
How turbocharger work?
Turbo connects to the engine exhaust. In turbo setups, the exhaust manifold may be specially designed for turbo placement and to handle increased heat and pressure. The turbo has two separate compartments: the turbine and compressor sections.
Exhaust flows to the turbine section as exhaust heat and pressure drive the turbine or exhaust wheel. Shafts connect the exhaust wheel to the compressor wheel. The compressor wheel pulls air in through the air filter and intake pipe. Its specially shaped fins force air through an increasingly smaller chamber building compression. Air gets hot during intake and compression so most turbo setups have an intercooler between the turbo and engine intake to get air back down to ambient temperatures. Cooler air has greater density serving the goal of forcing more air into the engine. The intercooler works like a radiator. Hot air passes through internal tubes as outside air rushes by to cool.
Here are some common turbo designs;
Single turbo: Exhaust flows through a single turbocharger.
Twin-turbo: A setup with two turbochargers for example on a six-cylinder engine with one turbo for each cylinder bank.
Twin-scroll turbo: Exhaust exists the cylinder in a pulse with a high-pressure section followed by low pressure. Twin scroll turbos separate cylinders into pairs so that exhaust pulse waves do not interfere with each other and a continuous stream of maximum pressure exhaust reaches the turbine.
- Turbos are more efficient this is because they use exhaust gases which are by-products of the combustion process in an engine to drive them.
- Turbo is more efficient which also means has more power potential but the downside is that it takes more time to make power also they make cool noises.
- The downside of this is that the power is not instant due to what’s known as turbo lag.
- Turbos take time to spool this is because the exhaust gases coming out of the engine are not going fast enough at low engine RPMs.
Let’s compare superchargers and turbos in very general items.
Superchargers are powered by mechanical energy for example by connection to an engine’s crankshaft while turbos are powered by otherwise wasted heat energy from engine exhaust.
Roots and twin-screw superchargers have positive displacement, meaning they move the same amount of air for each engine revolution regardless of RPM. This also means that they can make a boost immediately even at very low RPMs and have a fairly linear power curve.
Turbo setups produce an exponential power curve since they are powered by exhaust turbos that take time to build turbine speed and pressure before producing an unstable boost. This delay is called turbo lag.
Superchargers take power to make power and an average setup can require 40 to 60 horsepower to function. This doesn’t mean that overall engine efficiency is always sacrificed as some setups can increase fuel economy when not driven aggressively.
Though turbos do increase back pressure on the engine they derive power primarily from otherwise wasted exhaust heat as opposed to exhaust flow pressure as such they can be very efficient.
Which is better?
Turbos are used on more production vehicles and are generally easier to retrofit and have more power potential while superchargers are used on fewer production vehicles and are more complicated than retrofit to the vehicle. Since they are less efficient and have less total power potential. This gives turbos the edge in both ease of installation cost and power potential.
When it comes to buying a car with one of these it’s really up to you. The advantages of a turbo over a supercharger on a production vehicle are not going to be something that would make you select a turbo vehicle over a supercharger vehicle or a supercharged vehicle over a turbo vehicle and because the number of choices for supercharged cars is so limited. Most likely you are going to end up with a turbo car.
In conclusion, superchargers can be a less complex less expensive way to increase engine performance. They are usually easier to tune and maintain. They can be ideal in applications that require a predictable boost at all RPMs.
Turbos might require more peripheral parts like oil and vacuum lines an intercooler custom exhaust custom manifolds and exhaust piping and so on. Turbos can require more skill to properly configure however a well-tuned turbo system may be able to produce boost more efficiently and in greater quantity than a supercharger.