Most of us are not seasoned mechanics, but it always helps to understand the concepts behind how engines work. “Supercharging” and “turbocharging” or are terms you’ve probably heard before. These features are found in many modern cars, trucks and SUVs, but what do they mean?
Getting More From Less
Whether it’s supercharging or turbocharging, the goal is to extract more power from a smaller engine size than would otherwise be required. But how is this possible?
Well, before understanding how this happens, you have to first know how an engine works, so here comes some gross oversimplification.
An internal combustion engine (the common gas-powered engine) creates hundreds of little explosions in its cylinders every second. An explosion requires three things: air, fuel and a spark.
Just like starting a campfire. The simple way to get more power is to add more fuel, and this is how there used to be muscle cars that got just 9 miles per gallon.
The other way to add more power is to add more air (remember, this is an oversimplification), and you add more air by forcing it in using some kind of air compressor.
Turbochargers and superchargers are these air compressors. They operate in different ways and have different pros and cons.
The main difference between turbochargers and superchargers is their energy source. Turbochargers use the vehicle’s exhaust gas; two fans – a turbine fan and a compressor fan – rotate from exhaust gas. Conversely, superchargers are powered directly by the engine; a belt pulley drives gears that cause a compressor fan to rotate.
How Turbocharging Works
The key similarity between a turbocharger and supercharger is they both compress air and send it into the engine’s intake. Compressed air is denser, meaning more oxygen-rich, and when mixed with the right amount of fuel, creates more power.
Forced induction is often misconstrued, as some may think that simply pushing more air in will yield significantly more horsepower. This is not the case—it must be compressed to the point of being measured in pounds per square inch (PSI).
Typically, a turbocharger in any modern, unmodified car produces anywhere from nine to 20 PSI of compressed air. This compressed air is commonly referred to as boost pressure, or boost, for short.
The key trait of a turbocharger is it utilizes exhaust pressure to make power. As exhaust gasses exit the engine, they route through the turbocharger, spinning its turbine wheel. This is what’s referred to as the hot side.
On the other side is the cold side, where intake air is fed. Here, air is sucked in, compressed by the compressor wheel that’s spun by the hot side’s turbine via a shaft, and forced into the intake.
This is a very efficient way of increasing power as the engine is using exhaust energy that was on its way out of the exhaust system, so manufacturers determined a way to take advantage of it.
How Supercharging Works
Superchargers create compressed air in a more mechanical way.
The supercharger unit’s internals are connected to the engine’s crankshaft via a belt.
As the crankshaft spins, the belt spins at a certain ratio to it, creating significantly higher revolutions per minute (RPM) inside the supercharger that compresses the intake air, and forces it into the intake. There are different types of superchargers, but they all are spun via the crankshaft.
That’s the key difference between a turbo and a supercharger—turbos create boost from exhaust gasses, whereas superchargers create boost from the rotation of the crankshaft.
Comparing Turbochargers vs. Superchargers
Besides how the two devices work (explained above) another key difference is that whilst a supercharger requires engine power to run, a turbocharger runs off waste (exhaust) energy created by the engine.
This means that overall turbochargers operate with higher efficiency, utilising exhaust energy which is typically lost in naturally-aspirated and supercharged engines.
Turbochargers provide significantly increased horsepower for engines, especially allowing smaller engines to produce much more power in relation to their size, whilst simultaneously offering better fuel economy.
On the other hand, turbochargers tend to provide less boost at lower engine RPMs whilst the turbo spools up; the so called turbo lag.
Superchargers also increase engine horsepower and because they are driven by the engine’s crankshaft, provides good power at low engine RPM without any lag. The trade-off is reduced efficiency, given superchargers use engine power to produce engine power.
The reason why turbochargers are used most commonly in Europe is because the engines are small and four cylinders are standard.
Superchargers can deliver their boost at lower RPMs then a turbocharger, whereas the turbocharger works best at high engine speeds. Turbochargers are quieter and superchargers are more reliable. Superchargers are easier to maintain than the complex turbocharger.
supercharger vs turbocharger pros and cons Pros
Each of these power-boosting technologies has advantages and disadvantages, but the most obvious difference behind the wheel is a slight delay in how you respond to your right foot in a turbocharged car, especially when you hit the accelerator hard.
That’s because the turbocharger needs a moment to “spool up” before delivering its extra boost of power. It takes a second for exhaust heat and pressure to build up enough to spin the turbo after you step on the accelerator. It’s called “boost lag” or “turbo lag” for obvious reasons.
In contrast, a supercharger has no lag; Because its air pump is connected directly to the engine’s crankshaft, it’s always spinning and responding instantly. The power boost it offers, and with it the engine response you can feel through the seat of your pants increases instantly in direct proportion to how far you step on the accelerator.
While the main disadvantage of the turbo is boost lag, that of the supercharger is efficiency. As a supercharger uses the engine’s own power to turn itself, it siphons off power—more and more of it as the engine speed increases.
For this reason, supercharged engines tend to be less economical in terms of fuel consumption. However, for developing mega-power with instant kick-you-in-the-back throttle response, supercharging applies. It is used by several muscular machines such as the 650hp Chevrolet Corvette Z06 and 755hp ZR1, as well as Dodge’s 700+hp SRT Challenger Hellcats and Demons.
Difference between Turbocharger and Supercharger:
The main difference between a Turbocharger and a Supercharger are Turbocharger is not connected directly to the engine and whereas a Supercharger is a direct connection with the engine through the belt.
There are 19 points I have listed here.
So let’s start at each point.
| Sl No. | Turbocharger | Supercharger |
| 1. | The turbocharger is not connected directly to the engine. | The supercharger is a direct connection with the engine through a belt. |
| 2. | It has smog-altering equipment that lowers the carbon emission. | The supercharger does not have a wastegate. So the smog emits from a supercharger. |
| 3. | It uses exhaust gas for its energy. | It is a connected crankshaft of the engine for its energy. |
| 4. | The spinning rate is 15000 RPM | The spinning rate is 50000 RPM. |
| 5. | This is a device consisting of both the turbine and compressor mounted on the same shaft. | This is basically a compressor. |
| 6. | It does not need any extra power. | Here in the supercharger extra power is to be supplied. |
| 7. | It drew power from exhaust gases. | It drew power from the engine. |
| 8. | Higher speed achieved. | Greater acceleration is achieved. |
| 9. | It takes time to spin up to the speed hence there is lag. | Here no lag. Power delivers immediately. |
| 10. | Difficult maintenance. | Easy maintenance. |
| 11. | This is costly. | The cost is less. |
| 12. | More efficient because it drew power from exhaust gases. | A supercharger is less efficient. |
| 13. | Suitable for an engine with higher displacement. | Suitable for an engine with lower displacement. |
| 14. | Turbos won’t start operating until a sufficient amount of exhaust gases is produced. | Superchargers start working as soon as the engine starts. |
| 15. | Here a compressor is rotated by the turbine. | The compressor is rotated by the engine crankshaft through a belt. |
| 16. | This is more complex. | but this one is less complex. |
| 17. | The intercooler requires here to for lowering the temperature of compressed air. | The chances of the requirement of the intercooler are negligible. But some time is needed. |
| 18. | The compressed air has a high temperature in the turbocharger. | The compressed air has a low temperature in the supercharger. |
| 19. | This is less reliable. | This is more reliable. |
Turbocharger vs. Supercharger: Which Is Better?
Those are the on-paper differences, but what about on the road? Turbochargers and superchargers are not only designed differently and work differently, but they drive differently as well.
The direct connection of a supercharger to the crankshaft means as soon as the accelerator is pushed and the crankshaft turns faster, so does the turbine in the supercharger.
Response is immediate. In any and all driving conditions, the supercharger is always on, so when your right foot calls for more forward momentum, you get it right now.
With a turbocharger, as the engine speed increases, so does the amount of exhaust gas driving the turbine. Even with the most advanced turbochargers, the unit is only most effective within a certain rev range.
When you hit that level of engine speed, then the turbine is able to spin fast enough to force more air, and fuel, into the engine. It happens quickly but not instantaneously, resulting in what is known as “turbo lag”—putting your foot down and not getting a burst of acceleration for a second or two.
Though there is a delay, it’s one that can work in the favor of efficiency for turbochargers.
While a supercharger is always spinning and putting in more fuel and air, if a turbocharger only works above a certain engine speed, it’s possible to cruise with the efficiency of a smaller engine and then have the performance of a more powerful one when desired. It’s as easy as a push of the accelerator and the change of a gear.
Because of those differences, the decision of whether to choose a turbocharger or a supercharger for performance is a bit complicated. If instantaneous speed is the number one priority, a supercharger could be the right choice.
But if fuel economy plays a part in your decision, turbochargers have become today’s default solution for higher performance without lower gas mileage.