Supercharger vs. Turbocharger

May 26th, 2020 by

The terms “turbocharged” and “supercharged” have been apart of the English language since the discovery of race cars. The need for turbocharged and supercharged cars has been at an all-time high, with most manufacturers opting for turbocharged engines. And while both terms are commonly understood to mean that something is given added vitality, made more powerful or highly emotional, accelerated or boosted, most people do not understand the technologies that actually give meaning to those words. What are turbochargers and superchargers— and which one is better than that?

More Power Needs More Air

The amount of power the internal combustion engine can generate depends primarily on how much fuel it can burn and how quickly and efficiently it converts heat to mechanical force. But fuel requires air (actually air-contained oxygen) to burn, so the engine’s maximum output depends largely on how much air it can take to burn that fuel.

That is why the concept of forcing the engine to supply more air than it would normally consume, so that it can burn more fuel and produce more power. The extra intake air can be provided either by a turbocharger or a supercharger. These are both air compressors, but these functions and operate somewhat differently.

Two Forms With One Purpose

The turbocharger uses the velocity and heat energy of the hot (and expanding) exhaust gasses that run out of the engine cylinders to rotate a turbine that drives a small compressor or a propeller, which in turn returns more air to the engine. The supercharger also pumps additional air into the engine, but is instead mechanically driven by the engine via a belt that runs off the crankshaft or by an electric motor.

Pros And Cons

Each of these power-boosting systems have advantages and disadvantages, but the most obvious difference from behind the wheel is a slight delay in reacting to your right foot in a turbocharged vehicle, particularly if you drive deep into the throttle. That’s because the turbocharger needs a minute to “spool up” before providing its additional power burst — it takes a second for the exhaust heat and pressure to rise enough to turn the turbo after you push the gas pedal. It is called the “boost lag” or the “turbo lag” for obvious reasons.

A supercharger, on the other hand, has no lag; because its air pump is directly connected to the crankshaft of the engine, it is always turning and immediately reactive. The power boost it gives, and therefore the engine response you feel through the seat of your pants, increases immediately in proportion to how far you press the accelerator.

While the primary drawback of the turbo is boost lag, the efficiency of the supercharger. Because the supercharger uses the engine’s own power to rotate on its own, it siphons power— more and more of it as the engine climbs. For this reason, supercharged engines tend to be less fuel efficient. Nonetheless, supercharge rules for creating mega strength with instant kick-you-in – the-back throttle response. It is used by several big-muscle machines such as the 650-hp Chevrolet Corvette Z06 and 755-horse ZR1 and Dodge’s 700-hp SRT Challenger Hellcats and Demons.

Electric Supercharging

Recently, a third power-boosting alternative has come onto the market: electrical overcharging. The 2019 Mercedes-AMG CLS53 and E53 performance models offer a new, turbocharged 429-hp 3.0-liter inline-six turbo charger equipped with an electrically driven supercharger that complements the high-rpm turbocharger. The electric motor spins the compressor to provide a burst of low-rpm torque that fills the power gap normally felt as a turbo lag.

BorgWarner, the manufacturer of the system, says the electric supercharger “supplies on request until the turbocharger takes over, increases power at low engine speeds and almost removes the turbo delay.” Having driven this engine thoroughly, we can verify that it operates as advertised. It will soon be available on engines from at least two other car manufacturers.

In the meantime, we have a clear winner in this decades-long battle between power-boosting technologies— at least according to car manufacturers who have chosen turbocharging for almost all of their current power-boosted engines. But in reality, this arm-fighting match rages. The predictions are that both systems will operate side by side in the world of internal combustion engines.

The Winner Is…

Auto manufacturers have agreed that the turbocharger would prevail by a large margin. It’s not so much about energy, it’s about fuel efficiency. Federal requirements for ever-improving fuel economy, strict greenhouse gas emission regulations, and consumers ‘ demand for good fuel mileage have forced car manufacturers to use turbochargers rather than superchargers.

The turbocharger has provided the opportunity for automakers to replace a lot of V-6s with more efficient inline-fours turbocharged that provide at least equivalent power and often more throttle, while turbocharged turbo Global information company IHS Markit counts some 220 2018 models with at least one turbocharged engine compared to only 30 available with a supercharged engine.

One manufacturer, Swedish automaker Volvo, has decided not to choose between the two technologies. It currently uses both types of power boosters — a small, conventional (engine-driven) low-end turbocharger and a higher-rpm turbocharger— on some of its 2.0-liter inline fours.

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