- First Things First: What Is Forced Induction?
- What Is A Turbocharger?
- Twin-Turbo Vs. Twin-Scroll Turbo
- What Is A Supercharger?
- Turbocharger Vs. Supercharger
- What Is A ProCharger?
- Supercharger Vs. ProCharger
And what even is a ProCharger?
Once upon a time, a turbocharger was a mysterious thing that kicked in and delivered a whole new world of urgency to a car's acceleration, and a supercharger was something found on airplanes. Now, turbochargers are used on economy cars, and superchargers are strapped onto some of the most brutally fast muscle cars and trucks you can buy. Now a new name has made its way into the forced induction (we'll get to that term) lexicon next to supercharger, and that's ProCharger. What's the difference between a ProCharger and a supercharger? Is a twin-turbo the same as a twin-scroll turbo? We'll get into those questions as well.
First Things First: What Is Forced Induction?
In oversimplified but accurate terms, to make an engine run, a spark ignites a mixture of fuel, and air is burned to power the pistons that turn a crankshaft, the rotation of which is used to turn the wheels through a series of driveshafts. The ratio of the fuel-to-air mixture is essential to burn the fuel cleanly, but the more fuel burned means more power can be created. A naturally aspirated engine creates a vacuum to draw in air at its natural atmospheric pressure. That limits the amount of air that can get into a combustion chamber which, in turn, limits the amount of fuel that can be burned.
Turbochargers, superchargers, and ProChargers are all variations of forced induction, which forces more air into the engine so more fuel can be used and more power generated. Except that's not exactly correct. They compress the air (remember “natural atmospheric pressure”?), so more air can be mixed with more fuel to be burned.
What Is A Turbocharger?
The most common way of compressing air, or forcing more air into an engine, is a turbocharger. The main components of a turbocharger are turbines and a compressor. The first turbine is spun (powered) by gasses routed from the engine's exhaust manifold. A shaft connected to the first turbine turns the second turbine, which sucks in and compresses air to the engine allowing more fuel to be burned. It's an efficient system and often described as adding “free power” as it's driven by the byproduct of the engine and not mechanically driven as an accessory like, for example, an air conditioner's compressor that saps power when it's running. We go into more detail on this here.
Because a turbo uses exhaust pressure, which comes and goes as the car accelerates and decelerates, there's not enough pressure at low RPM to get the turbo to an adequate speed. A single turbo takes a few moments before the ignition system can take advantage of the extra air, known as turbo lag. This brings us to common variations of turbocharging and the supercharger.
Twin-Turbo Vs. Twin-Scroll Turbo
Both sequential twin-turbocharging and twin-scroll turbochargers seek to address the issue of turbo lag. It's also where turbocharging goes from simple, in engineering terms, to complicated. A twin-turbo car is exactly what it sounds like – a car with two turbochargers under the hood. How the second turbo is used can vary, but it adds up to even more power. They can be run together or sequentially. When run sequentially (one turbo comes on at a time), one of the turbos is smaller than the other, allowing it to spool up quicker and deliver extra power sooner; then, at a certain point, the second, larger turbo takes over. A twin-scroll turbo is a single unit with two chambers of different size and shape. The smaller chamber provides a quicker response, and the larger one is there to combine later for peak performance. The added complexity comes from changes in the amount of air entering the ignition system, which is a challenge for engine management software. Due to the added cost and complexity, you don't typically see twin-scroll turbos on more economy-focused cars.
What Is A Supercharger?
Essentially, a supercharger performs the same job of forcing compressed air into the engine but is driven mechanically by the engine as an accessory, typically by a shaft, gears, or a chain. There are two main types of superchargers. A centrifugal supercharger uses a turbine like a turbocharger; a Roots charger uses two rotors with lobes to compress the air, while a twin-screw supercharger uses screws similar to worm screws to compress the air. This uses a similar principle to a Roots charger, but there are more “edges,” and the air is compressed earlier.
There is a variation of the supercharger that's powered by electricity. Electric superchargers use the centrifugal system powered by the car's electrical system. However, they haven't become popular as the standard 12-volt power supply isn't powerful enough to run a supercharger. However, with 48V systems being adopted recently, they are becoming more common.
Turbocharger Vs. Supercharger
Turbocharged engines are more common than supercharged ones for one main mechanical reason. Supercharger engines are rarer from the factory as the engine needs an output added to power the unit, while a turbocharger just needs a modification to the exhaust manifold. Turbocharged engines have become adopted into mainstream cars as they are more efficient than superchargers and allow smaller engines to make equivalent power of larger units. However, a turbocharger needs to spool up using the exhaust gasses, which takes time for full power to arrive – usually at around 3,500 rpm or more. A supercharger's main benefit over a turbo is that its effect is typically immediate as it's often driven directly by the engine. That's why Dodge chose to supercharge the V8 for its highly proficient Challenger Hellcat model and subsequent iterations. The downside is that because it's always compressing air, it's always demanding more fuel, so it's not ideal for fuel consumption on road cars.
What Is A ProCharger?
ProCharger is a brand that makes a range of turbo and superchargers, but the name is being heard more and more due to one specific type of supercharger the company sells. It's a centrifugal supercharger that uses an impeller, a piece that sucks in air to the center while rotating then spreads it evenly from the center on the other side. The difference between supercharger and ProCharger is that the ProCharger delivers smooth and consistent extra air to the engine, making the engine smoother to control. ProChargers are mostly found on race cars where power is often limited by rules and smoothness and predictability of an engine under acceleration is a key dynamic.
Supercharger Vs. ProCharger
A ProCharger-design supercharger will help boost more power from a smaller, more typical unit. However, it's not all sunbeams and rainbows. It's a more efficient design, but that difference in power comes at higher RPMs, making it less than ideal for general street use, although that doesn't mean they aren't for street use. That depends on suitability for the car and use. ProChargers are also more expensive and generally cost-prohibitive for a street build. If you're weighing up the option of a supercharger or ProCharger, ProChargers are more efficient and use less gas over time. However, typical superchargers deliver their extra boost instantly, which is perfect for running fast quarter-mile times from a standstill. ProChargers are mostly seen in race cars where getting off the line isn't as important as the rest of the race, as they split the difference between the power delivery of a supercharger and a turbocharger. If you want out-and-out power, a Roots supercharger is likely the best option.
Like so many things, there is no clear answer to the question, “what's better, a ProCharger or a supercharger?” It boils down to application and budget. You're going to have to weigh up the pros and cons first. There's no wrong answer.
Keyword: A Quick Guide To Forced Induction