Besides certain exceptions such as electric vehicles, the vast majority of vehicles on today’s roads use internal combustion engines (ICE). In ICE vehicles, the combustion of fuel mixed with air occurs inside a combustion chamber, which generates pressure that acts on the pistons. The engine then converts this pressure into rotational motion.ICE vehicles can further be mechanically classified into naturally aspirated and forced induction designs. The vast majority of ICE vehicles use natural aspiration, relying solely on atmospheric pressure to supply the air needed for combustion. In other words, naturally aspirated engines do not deliver compressed air to the intake.This is the crucial difference between naturally aspirated and forced induction engines. As the name suggests, forced induction engines utilize compressors which deliver compressed air (air with an increased pressure, temperature, and density) into the intake of an engine. In effect, this results in increased engine power and efficiency.Here’s where another level of classification is introduced: all forced induction engines utilize compressors, but two distinct types exist. You’ve likely heard the terms supercharger and turbocharger before—especially since many manufacturers are shifting to turbocharged engines—but what do they really mean?
SUPERCHARGERS
While both superchargers and turbochargers are effectively air compressors, their mechanical operation is quite different. Naturally, this translates to tangible real-world differences in power delivery, lag, and complexity. Superchargers trade blows with turbochargers but neither design will be a clear winner for all consumers.Superchargers derive their power from a belt, gear, shaft, or chain connected directly to the crankshaft—the mechanical component of an engine which drives the pistons and converts their reciprocating motion into rotational motion. While sound in principle, this connection comprises the first evident disadvantage of superchargers.Notably, efficiency is impacted by this mechanical connection. While a supercharger provides a net increase in power, it also saps power from the engine in order to power its own operation. However, this disadvantage may be negated by the increase in power, lack of lag, and abundance of usable power (even at low RPMs) that superchargers provide.
TURBOCHARGERS
Instead of using the crankshaft for its operation, a turbocharger is driven simply by the exhaust gases of an engine. In this design, exhaust gases are routed through a turbine that itself spins the compressor. With power derived solely from exhaust (or waste) gases, turbochargers avoid the pitfall of parasitic engine power loss which affects superchargers.Thus, turbochargers are more efficient than their supercharged cousins while retaining a hefty increase in power over naturally aspirated engines of identical displacement. This translates to better fuel economy, which is part of the reason why some modern manufacturers are downsizing their engines while adding turbochargers.Even smaller engine displacements (such as those used in economy cars) can benefit from the turbocharger treatment. However, turbochargers aren’t without their own demerits. Turbo lag is a pervasive concern although modern designs minimize its effect, especially when applied in sports or performance vehicles.
WHICH IS BEST?
While both superchargers and turbochargers provide excellent increases in power, the two designs accomplish this in vastly different ways. With certain disadvantages affecting each, there is no clear winner when choosing a supercharged or turbocharged vehicle. Instead, consumers must carefully weigh which aspects of each design appeal to them most.For one, superchargers are generally less expensive than turbochargers. This, combined with a complete absence of lag in power delivery—as well as usable power even at low RPMs, which some turbocharged engines lack—ensures that superchargers remain a viable option for a wide variety of performance vehicles.While turbochargers will generally be more expensive than superchargers, this disadvantage may be offset by the significant increase in power, fuel economy, and efficiency that they provide. Although a turbo-equipped vehicle will have to contend with some lag and greater oil consumption, turbochargers are still the preferred choice by many.What if you’re unsatisfied by either? You may just be interested in twincharging! As you may have guessed, twincharged engines utilize both a supercharger and a turbocharger operating in tandem. This effectively negates the respective disadvantages of superchargers and turbos alike while retaining their respective advantages.However, twinchargers are almost always exclusively aftermarket options which are high in cost and add another level of complexity to an engine. For most consumers, either a supercharged or turbocharged vehicle will suffice for all manner of tasks from daily driving to long days at the track.Given the choice, what supercharged or turbocharged vehicle would you add to your own garage? Sound off in the comments below!
