Why Supercharger Decrease Gas Mileage (& Daily Driving Tips)

By February 20, 2022Supercharger

Superchargers decrease gas mileage because they allow more fuel to be used up during combustion and they are spun directly by the engine. 

Superchargers are connected to the engine and get spun by the engine. Which means a supercharger technically uses up some of the power from the engine to operate. Thus, reducing gas mileage. 

Although, the supercharger functions as a forced induction that allows for more than 100% volumetric efficiency. Unlike traditional aspirated engines, they can bypass displacement and pump more air by reducing the force required by the engine to draw air. 

What you get from the supercharger is more force but a reduced gas mileage.

I have tried the supercharger on my ford  281 cubic inches/4.6-liter engine, and here is what I discovered.  After some aftermarket modifications were added to my car, including filter and exhaust, I achieved a higher fuel consumption, but the boost to my engine’s power was great. 

Related article: Supercharger 101: Horsepower, Cost, Engine Damage & Tuning

Superchargers reduce the vehicle’s gas mileage because the supercharger increases air intake by compressing more air  – which uses more fuel during combustion to create more horsepower.

Also, a supercharger is powered using a belt that relies solely on the engine to work. The engine, therefore, needs extra energy to power the supercharger through the belt, which makes the car consume more fuel, thus, decreasing gas mileage.  

That said, gas mileage differs for each in the market today.  The secret to having better gas mileage on a supercharged engine is to ensure the belt can spin smoothly. This allows the supercharger to work more efficiently and improve gas mileage.

Car brands like ford and Mercedes have been able to figure out how to apply this key to their vehicle.  Mercedes use the clutch system for their supercharger.  The clutch supercharger only boosts the car when necessary, saving fuel on a standard drive.

Although the general assumption is that superchargers will increase fuel consumption, this could be true of most superchargers, but not all.  The root superchargers will increase fuel consumption in your car, but with a root blower, you can reduce the amount of fuel consumed due to the use of a supercharger. 

When getting a supercharger, a root-type blower that comes with a complete bypass system will help provide your car with good fuel economy and power.  This type of supercharger allows your vehicle to remove excess air pressure to decrease the energy that it takes to keep the supercharger running, thereby saving fuel. 

Another type of supercharger that does not increase fuel consumption is the centrifugal supercharger.  This type of supercharger will consume the same amount of fuel as a regular engine when being used under regular throttle.   

Image of supercharger

Supercharger is spun by a belt that’s connected to the engine. Which means supercharger uses some fuel to operate.

How much gas mileage do you lose with a supercharger?

With superchargers, a car owner should not expect a gas mileage of less than 20mpg. The usual gas mileage you would get is 30mpg or more. This is because supercharged engines use fuel to operate and make your engines use more fuel for power,

Superchargers, as we know, are not powered by the exhaust, unlike some other types of boost.  The charger is powered by the engine using rotors and belts.  The belts power the superchargers, allowing air to mix with the fuel. 

The supercharger requires a lot of energy to run because, unlike the turbocharger, which uses exhaust, it is powered by the vehicle’s engine. An increase in energy required to run the supercharger means an increase in fuel consumption. 

Furthermore, this means, for a normal engine using 2 liters to go the distance, a supercharger could require more than 2 liters to run the same length.  

anatomy of combustion chamber

Supercharger increases the amount of air inside combustion chamber. This allows more fuel to combust and give more power (at the expense of higher fuel consumption).

Does a supercharger run all the time?

Supercharger runs as soon as the vehicle starts up, producing instant power to your engine (unlike turbo engines). The reason is that the supercharger is attached to the engine and runs together with the car engine.

However, a typical supercharger will only kick in after 1500 RPM. So don’t expect any boost on low RPM (this is by design).

That said, some superchargers allow you to turn off the supercharger whenever you want, like in the Mad Max movie.  Some superchargers come with an electric clutch that helps the driver regulate the use of the supercharger.

Related article: Which Is Better: Supercharger or Turbocharger?

Can you daily drive a supercharged car?

Supercharged cars can be driven daily; they are reliable and easy to maintain. Many stock cars even come with superchargers from the factory – so it’s normal to daily drive a supercharged car.

A supercharged car can be properly maintained by ensuring that you change the oil regularly and have regular engine maintenance.

Compared to other types of improvement that could be made to an engine like the turbocharger, which could linger sometimes, the supercharger is seen as a better way to boost engine performance without spending a lot on installation or maintenance. 

Also, a cool-down period is not required for the supercharger, unlike other boost types like the turbocharger that can cause additional strain on the vehicle’s engine when driven for long. 

Here are 2 reasons why supercharged engines make a good daily driver.

  1. Relatively affordable. The cost of installing and maintaining a supercharger is lesser when compared to other boosts.  It is also effortless to install and maintain, which you can do with the proper knowledge.
  2. Supercharger has no lag. Super is highly responsive to the engine because it’s powered directly through the engine.  Other boosts like the turbocharger, which relies on the exhaust system to power up, tend to lag and take a little time before responding to the engine.

Can you turn off a supercharger?

Depending on the installation, some superchargers can be turned on or off using an electromagnetic supercharger clutch.

An electromagnetic supercharger clutch allows for a switch that lets drivers turn on or off the supercharger when they choose to.

The electromagnetic clutch serves as a switch that helps transmit and cut off power.  It works with the electromagnetic force, which is produced using energizing coils.  

Which muffler is your car right now?

The superchargers that are regularly available for buying have an air conditioning compressor type of electric actuation clutch.  Like the scene in Mad Max, this clutch the supercharger to be turned on or off.

Will the supercharger damage my engine?

A properly fixed and maintained supercharger will not damage your engine. Supercharged engine is quite common even for stock cars – so engine damage shouldn’t be a concern.

The supercharger will not damage the engine once appropriately installed, maintained, and checked adequately.  A boost is a safe form of enhancing your engine performance. 

Also, superchargers can be used on both manual and automatic cars without fearing it causing damage to the vehicle.  It is possible to supercharge a stock engine, which is safe and will not damage the engine.

Although it is essential to know the limit of the engine that your car uses, not all superchargers can be used for your vehicle.  Some superchargers are built specifically for a particular vehicle brand and, when installed on the wrong car, can ultimately damage the engine.     

Do superchargers affect reliability?

A supercharger does not affect the reliability of your supercharged engine; if anything, it is one of the most reliable boosts you can use for your car. 

Many people do not trust the reliability of their super-boost engine, mainly because they feel a supercharger that gives such a boost to cars must come with a side effect, which is not valid. 

Several things could make superchargers fail or affect the performance of the vehicles.  These reasons are not the fault of the supercharger; they are mainly related to installation and maintenance problems. 

Here are common reasons why superchargers fail:

  1. No oil or low oil supply. Lack of oil in supercharger will lead to an increase in heat, making the gear turn black or blue.  This could make the gear teeth begin to wear off.  This is why it’s important to refill the oil in your supercharger.
  2. Overfilling with oil. Overfilling the engine with oil could also cause the supercharged engine to overheat, which means heating the oil, which then hardens the front case seals, increasing oil consumption.
  3. Excessive use. Subjecting the engine to excessive use will also cause the engine to damage or worse.  Hight boost racing conditions can cause the supercharger to heat up.
  4. Hot Air Below Filter kit. Excessive hot air can make a supercharger overheat – which could cause rotor failure.  Many deceptive filter kits are sold to people in the name of cold air kits, which get a lot of hot air into the engine.

 

These are some of the causes of supercharger failure, and this is why regular maintenance of the supercharged engine should be done after installing a supercharger.

Superchargers are very reliable and can travel for an extended range without damaging the vehicle.  The charger has a cooling system that allows hot air to exit the charger and allows cooler air from the cooler pipes to cool down the charger. 

This makes the charger last longer and also prevents overheating. 

4 Daily Driving Tips To Improve Gas Mileage

Taking good care of your car engine and the car can improve your engine efficiency and increase gas mileage in your vehicle.  Here are top tips you should try frequently:

  1. Clean air filter: There is a direct relationship between fuel and engine consumption; this means that the more fuel your engine burns, the more air it consumes.  Dirty air means that your engine consumes more fuel than air, resulting in less gas mileage.
  2. Clean engine oil: If you don’t know the right oil to use for your engine, check the engine’s cover to see the company-recommended engine oil.  I would recommend using lighter oil because of the lighter the oil, the less friction in the engine per pump, and the more fuel economy.  Don’t forget to change oil frequently.
  3. Check air pressure: improper air pressure increases rolling resistance, resulting in poor mileage.
  4. Try conservative driving: Driving at full speed and fluctuation mph may result in more MPG.

Read: Exhaust Headers & Fuel Economy: Why Headers Improve Mileage

Conclusion

Superchargers decrease gas mileage and are not a great way to improve fuel economy. Although they provide many benefits to car owners, including more horsepower to car engines.

To get an increased gas mileage for your supercharger, you can opt for a centrifugal supercharger or install an electromagnetic clutch that will help you regulate the use of the supercharger.

Ifandi L.

Ifandi L.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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