How Does a Supercharger Work?

Learn about the basics of supercharged engines, the three main types of superchargers, and whether it’s a good choice for your vehicle.
Written by Bonnie Stinson
Reviewed by Melanie Reiff
Superchargers increase a vehicle’s horsepower by forcing more air into the engine. If you need more power for towing a heavy load—or if you want a more exciting automotive experience—a supercharger could be the answer.
The simplest way to get more horsepower is to increase the size of the engine. But for most people, that’s not the best option. Some drivers opt for supercharged engines, which can get more power out of a standard engine by using compressed air. Some automakers, like Mercedes and Jaguar, already include supercharged engines in a few models—but you can also buy and install your own aftermarket supercharger.
Keep reading to learn how superchargers work, the three different types of superchargers, the top benefits and drawbacks of supercharged cars, and common FAQs about superchargers. Epic cars need serious protection, so don’t skip tips from
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What is a supercharger?

A supercharger is an air compressor that is bolted onto an internal combustion engine. It compresses the air before it reaches the engine to create a forced induction system. 
In simple terms, a supercharger produces more intake air, which allows more fuel to be used—and the result is higher power output.

How do superchargers work?

To understand how to achieve more power, let’s start with a basic explanation of the air intake and combustion process on a four-stroke, naturally aspirated engine. 
When the piston moves down, a vacuum is created inside the cylinder, which draws air into the combustion chamber. Fuel is added, and then the mixture is ignited by the spark plug. An explosion occurs, which moves the piston back again. This movement is ultimately sent to the wheels, powering your vehicle.
For more engine power, you need to add more fuel—but more fuel requires more air. 
Enter the supercharger! The supercharger uses compression to increase the amount of air so that you can safely use more fuel and increase horsepower. 
A supercharged car needs an intercooler to cool down the air before it enters the engine, as compressed air is too hot for combustion. Due to the laws of thermodynamics, colder air intake will create more energy during combustion—resulting in more power output!
Most superchargers are powered mechanically using either a belt, chain, or shaft that physically connects to the engine’s crankshaft. There are two basic categories of mechanical superchargers: positive displacement superchargers and dynamic compressors.
Positive displacement superchargers deliver steady pressure at all engine speeds. The Roots-type blower and twin-screw supercharger fit into this category. Dynamic compressors adapt as the engine goes from low RPMs to high, sending increasingly pressurized air to the engine. This type of supercharger is more efficient but it doesn’t provide as much of a boost at low RPMs. Centrifugal superchargers fit in this category.
There are also electric motor superchargers, but these are far less common since they require a large alternator and a robust electrical source.

Different types of superchargers

The three most common types of superchargers are Roots-type, twin-screw, and centrifugal. They differ mainly in how they deliver air to the intake manifold, although they’re all mechanically powered. 

Roots-type superchargers

Invented by the Roots brothers, Roots-style superchargers work by using two (or sometimes three) rotors that mesh together, compressing air in pockets between the lobes. They release air in distinct discharges, rather than continuously.
For this reason—and because they’re so darned heavy—root-type superchargers are the least efficient of all superchargers.
A roots supercharger typically sits on top of the engine. You may see them in muscle cars and hot rods, protruding out of the hood. 

Twin-screw supercharger

This supercharger uses two spiral rotors that enmesh (like twin screws), turning in opposite directions to compress air. Thanks to the conical taper shape, the air is compressed inside the rotor housing with a twin-screw supercharger. As the air pockets grow smaller, the air is forced into a smaller space.
Twin-screw superchargers are efficient—but they’re also costly. It takes precise manufacturing to produce these rotors. These superchargers tend to produce a noisy whine that must be counteracted with noise suppression.
MORE:

Centrifugal superchargers

This is a small, belt-driven supercharger that looks a bit like a snail shell or a French horn. It is attached to the front of the engine, not the top. Its pulley activates a gear system that rotates a turbine, compressing air through centrifugal force as the engine revs.
First, the air is drawn into the hub of the impeller wheel in the center. Then, the air is moved outward at high speed. A diffuser (a set of vanes) slows down the air molecules, converting the high-speed low-pressure air into low-speed high-pressure air. You may have heard the recognizable drone of a centrifugal supercharger on a
Ford Mustang
or
Dodge Charger
.
Due to their high efficiency, centrifugal superchargers are the most preferred superchargers today. 
MORE: 10 affordable American muscle cars

Pros and cons of superchargers

Supercharger advantages

The major advantage of a supercharger is increased horsepower. After installing a supercharger, the average increase in engine performance is about 50%. The average torque improvement is 31%.
A supercharger is cheaper to install and easier to maintain than a turbocharger. It requires fewer external components, which means you’ll save money and labor. Superchargers also provide a constant boost, unlike turbochargers. 
Finally, superchargers can be surprisingly beneficial in high altitudes. If you live in a mountainous area with a high elevation, the air will be thinner. This means lower density and lower pressure. A supercharger can help an engine perform optimally in these environments.

Supercharger disadvantages

In exchange for the greater horsepower offered by superchargers, you’ll suffer from an average 20% reduction in fuel economy
If you value efficiency, then you should know that superchargers are much less efficient than turbochargers. Turbochargers utilize energy from the exhaust system that would otherwise go to waste, whereas superchargers must steal energy from the crankshaft.
The added strain on the engine is a serious disadvantage of superchargers. To handle the bigger explosions, you’ll need costly heavy-duty components. Even then, supercharged engines can wear out more quickly.
Finally, most manufacturers recommend high-octane premium-grade gas in supercharged cars. This fuel costs more than low-octane gas, adding to your overall cost of car ownership.

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FAQs

A supercharger uses compression to increase the amount of air in the combustion process. This results in more horsepower—and you may get a distinctive whine reminiscent of your favorite muscle car!
Both provide the engine with more cool air, resulting in higher power output. However, the energy source is different. A turbocharger works via a turbine that is powered by exhaust gases. Superchargers are mechanical, using a belt or chain connected to the engine’s crankshaft. Turbocharged engines experience turbo lag where.
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