Turbocharger vs Supercharger - which is better?

You've probably heard both words before. And both are associated with fast cars. But for many drivers, they are unfamiliar with the workings of a turbocharger vs a supercharger. And the bigger question - which is better?

Before we answer that question, we first have to understand how each of them works. They are both known as forced induction systems, meaning they will compress the air flowing into the engine, providing more power to the car. The more air you can force into your engine, the more power it will make. The main difference between a turbocharges and a supercharger lies in how the power is supplied to the engine. 

A turbocharger uses the velocity and heat energy of the hot exhaust gases rushing out of an engine's cylinders to spin a turbine that drives a small compressor, or impeller, that in turn stuffs more air back into the engine. Turbochargers generate additional power using exhaust discharges that is otherwise wasted when it is released into the atmosphere.

A supercharger also pumps additional air into the engine, but it is instead driven mechanically by the engine via a belt that runs off the crankshaft or by an electric motor.

Generally, turbochargers are quite while superchargers are more reliable and easier to maintain. 

Advantages of a turbo engine : 

Fuel efficiency : A turbo allows a smaller engine to match larger engines in performance while consuming less. This fuel efficiency is one of the most important advantages of turbochargers.

Lower emissions : Better fuel efficiency means lower emissions of CO2 into the atmosphere. Have you noticed that more and more governments around the world are talking about reducing emissions? This is in response to global warming, and the use of turbochargers allows manufacturers to design new vehicles that are lighter and cleaner without performance loss. You get performance, and help the environment by emitting less.

Driving pleasure : Turbocharged engines deliver greater power output and torque, which in turns improve your vehicle’s speed, responsiveness and performance on the road.

Disadvantages of a turbo engine : 

Turbo lag: turbochargers, especially large turbochargers, take time to spool up and provide the boost which gives you the feeling of being pushed back into your seat. 

Boost threshold: for traditional turbochargers, they are often sized for a certain RPM range where the exhaust gas flow is adequate to provide additional boost for the engine. They typically do not operate across as wide an RPM range as superchargers.

Power surge: in some turbocharger applications, especially with larger turbos, reaching the boost threshold can provide an almost instantaneous surge in power, which could compromise tyre traction or cause some instability of the car.

Oil requirement: turbochargers get very hot and often tap into the engine’s oil supply. This calls for additional plumbing, and is more demanding on the engine oil. Superchargers typically do not require engine oil lubrication.

Now let’s get into the pros and cons of a supercharged engine : 

Advantages of a supercharged engine :

Increased horsepower: adding a supercharger to any engine is a quick solution to boosting power.

No lag: the supercharger’s biggest advantage over a turbocharger is that it does not have any lag. 

Power delivery is immediate because the supercharger is driven by the engine’s crankshaft.

Low RPM boost: good power at low RPM in comparison to turbochargers.

Price: cost effective way of increasing horsepower.

Disadvantages of a supercharged engine :

Less efficient: the biggest disadvantage of superchargers is that they suck engine power simply to produce engine power. They’re run off an engine belt connected to the crankshaft, so you’re essentially powering an air pump with another air pump. Because of this, superchargers are significantly less efficient than turbochargers.

Reliability: with all forced induction systems (including turbochargers), the engine internals will be exposed to higher pressures and temperatures, which will of course affect the longevity of the engine. It’s best to build the engine from the bottom up to handle these pressures, rather than relying on stock internals.

Can I have the best of turbocharging and supercharging?

There has been discussion around this. Ideally, a supercharger would be great so you get the boost at low RPMs, while a turbocharger would give you power at a higher rotation (RPM). Volkswagen has attempted this with a twin charger engine. Besides being very expensive, the twin charger engine also only operates with premium gasoline. 

Volvo also has a twin charged polestar engine.

The future of turbos : 

We’ve seen the rise of electric cars. Now, electric turbos will likely be more common in future vehicles, where an electric motor spools up the turbo at low RPMs, producing useful boost until the exhaust gases are sufficient enough to power the turbo.

This is exactly what’s happening in Formula 1 with the ERS system, and it’s the solution to the turbo’s biggest disadvantage - turbo lag.

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