Supercharger or Turbocharger: What’s the Difference?

belt-driven supercharger
This Roots-type supercharger pulls even more power out of this hot rod V8.

Skyhobo / Getty Images

While automakers are increasingly turning to smaller engines for better fuel economy and lower emissions, drivers continue to expect at least the same amount of power for basic performance needs. To meet both goals, forced induction via a turbocharger or supercharger could be the answer.

Tip: Regular Oil Changes

Regular oil changes are essential to keeping your turbocharger or supercharger running in peak condition. Superchargers have their own oil system, while turbochargers share theirs with the engine.

Forced induction refers to some way of forcing more air into the engine than would normally be drawn into it. Naturally-aspirated engines have a continuous vacuum in the intake system, as cylinders on the intake stroke pull air in past the throttle body. Forced induction engines use a pump (most commonly a turbocharger or a supercharger) to force air into the intake. Because air is a compressible gas, the result of pressurizing the intake and cylinders is more oxygen. More oxygen mixed with more fuel results in more power.

There are two ways forced induction is put to use. For those interested in performance, adding forced induction can significantly increase engine power and torque, such as on Shelby GT Mustang engine options. Forced induction can also give smaller engines the same power as a larger, less-efficient engine. The overall result is better fuel economy without sacrificing power, perhaps the best of both worlds.

Types of Forced Induction

There are three types of forced induction pumps and three ways to drive them. All function slightly differently and have different strengths and weaknesses.

turbocharger cutaway
Here, a cutaway turbocharger reveals its inner workings. The exhaust side (red) drives the intake side (blue). Dave Rudkin / Getty Images
  • The typical turbocharger is a centrifugal pump driven by exhaust gas. Centrifugal pumps are variable-displacement, which means they change output depending on how fast they’re driven.
  • The typical supercharger is a positive-displacement pump driven by a belt of the engine crankshaft. Positive-displacement pumps compress the same amount of air every revolution. Roots-type superchargers, also called “blowers,” use meshed multi-lobe rotors to compress intake air. Lysholm twin-screw rotors are similar, but more expensive.
  • ProCharger is actually a brand name, which refers to a belt-driven centrifugal pump. Instead of being driven by exhaust gases, the ProCharger is driven by a belt.

More recently, as electric motors are finding wider application in the automotive world, particularly with the advent of hybrid electric vehicles, yet another way to drive forced induction pumps has been devised. Instead of a belt or exhaust, these are driven by an electric motor. Formula 1 engines use an electric motor to drive the turbocharger at low engine speeds, then allow exhaust gases to drive it at higher engine speeds.

Which is Better, or Why Not Both?

Because of the way that these forced induction pumps operate and are driven, there are various advantages and disadvantages. For add-on forced-induction, such as for sports cars, track cars, or “just because,” much of your choice will depend on engine configuration, whether you want to pass emissions testing, and your budget. Here are a few more factors:

twincharger Volkswagen engine has both turbocharger and supercharger built-in
This “Twin-Charger” Volkswagen engine has both a turbocharger and a supercharger, for the best of both worlds. Car Culture / Getty Images
  • Exhaust-driven turbochargers don’t deliver boost at low engine speeds. This is referred to as “turbo lag” and can catch inexperienced drivers off-guard. These don’t add much drag to the engine, so cruising and idling doesn’t use much fuel. When you need power for passing or acceleration, there is a slight lag before full boost and power is achieved. Because they’re mounted on the exhaust, extra room is needed in the engine bay around the engine.
  • Belt-driven superchargers deliver boost at all engine speeds, so there is no lag in power delivery. This is easier for many drivers to become accustomed to. At the same time, because it is directly driven by the belt, it increases drag on the engine, leading to poorer cruising and idling fuel economy. Depending on the type of supercharger, you may need room on top of the engine for installation, which is why some supercharger engines feature hood cutouts or bumps.
  • Aftermarket exhaust-driven turbochargers tend to cost more than belt-driven superchargers, and it’s good to consider a specialist if you plan on maintaining, diagnosing, and repairing one. Keep in mind, too, that more engine power will increase wear and can damage the rest of the drivetrain, such as the transmission, differentials, and axles. Upgrades or repairs will add to running costs.
    twincharger 2015 Volkswagen Golf 1.4 TSi BlueMotion
    Forced induction gives this 1.4-liter hatchback the power of a 2.0-liter engine. RL GNZLZ / Flickr

    If pure power is your concern, or you want the best of both forced induction options, twin-charging is the way to go. This isn’t just limited to supercars, however. The Nissan Micra / Nissan March Super Turbo is a twin-charged daily-driver hatchback, and Volkswagen / Audi’s 1.4 TSI engine is found in many of the automaker’s hatchbacks, sedans, and SUVs. Other automakers are similarly finding use for the twin-charging, and it’s highly likely we’ll see increased use of electric-turbos as the technology trickles down to production models.

    How to Maintain Your Turbocharger or Supercharger

    Whether you’ve bought a supercharger, turbocharger, or a vehicle with one or both already installed, maintaining your forced induction system will ensure consistent performance, fuel economy, and reliability. The main thing you need to know here is oil changes. Considering superchargers spin up to 72,000 rpm and turbochargers up to 300,000 rpm – most street engines run to 7,000 rpm maximum – consistent lubrication is critical to keeping them running. Also, compressing intake air generates a lot of heat.

    engine oil change
    Keep your turbocharger running with regular oil changes. vm / Getty Images

    To address these, make sure you change the oil on time, every time! Superchargers have their own oil system, which some manufacturers recommend changing annually. Turbochargers share their oil supply with the engine, which make regular engine oil changes an important part of forced induction maintenance. Finally, whether your car, truck, or SUV features a factory or aftermarket supercharger or turbocharger, knowing when to seek professional help will keep your force induction system working as intended.