While most Singaporeans are familiar with the term turbocharging, supercharging has been around for just as long. However, the majority might not understand how it functions. So, here is a rundown on how it works:
The basic principle of forced induction is adding more air into the combustion chambers via a supercharger or a turbocharger. More air, more oxygen. And oxygen in the air-fuel mixtures equals more combustion. Or more bang.
The key differentiating factor between a supercharger and a turbo is that a supercharger doesn’t use the exiting gases from the exhaust manifold. But we’ll get back to that.
In a nutshell, a supercharger is an air compressor, and there are 2 different supercharger types. Dynamic compression superchargers, and positive displacement superchargers. And both serve to force more air into the engine. In both instances, the supercharger works by drawing power from the crank. In essence, it is siphoning power from the engine to generate boost, enabling the supercharger to “suck” more air from the intake to generate power.
Here are two of the most commonly found types of superchargers:
Centrifugal superchargers are a type of dynamic supercharger. Like a turbo, these have an impeller or a turbine to suck air into the engine. Unlike a turbo however, the impeller is driven by a belt connected to the engine. These superchargers draw air in and compress it, before sending the highly pressurised air into the intake manifold.
These superchargers are expensive, but are better at improving engine power output than other superchargers due to improved heat transfer, resulting in lower air temperatures and denser air.
The Roots supercharger is the oldest type of supercharger. It can trace its “roots” (pun intended) to the mid-1800s, being used in industrial applications like pumping air into blast furnaces, or ventilating mine shafts. These days however, you can find Roots superchargers in high performance high horsepower engines.
Inside a roots supercharger, two rotary vanes with lobes funnel air from the intake to the discharge before the air is fed to the intake manifold. Twin Vortex and twin-screw superchargers operate the same way, albeit with differences in lobe or rotor designs. But these superchargers are not as efficient at transferring heat as a centrifugal supercharger. Hence, they generally add less power.
Because a supercharger draws power from the engine, they have no lag as compared to turbos. When you put your foot down, the power kicks in right off the bat and you’re met with a surge of acceleration.
However, some modern mild hybrid systems use an electric motor to drive the supercharger, taking the load off the engine to boost power. And improve fuel economy.
In some instances, the supercharger requires a lot more power to operate. A great example is the Dodge Challenger Hellcat. Or the Dodge Demon. In a “standard” SRT-8 Challenger, the 6.2L Hemi-V8 usually puts out 485 horsepower. But in its supercharged Hellcat guise, it almost doubles the power output and puts a whopping 707-horsepower to the rear wheels. And 797-horsepower for the Hellcat Redeye. But to attain those figures, the supercharger draws 80 horsepower from the crank. That’s the power of a small hatchback.
So, it all boils down to priorities. Would you sacrifice power, before gaining power? Or would you rely on your car’s exhaust gasses to give your car more power? It is “free energy” after all.
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