As government legislation and environmental concerns drive a shift away from fuel-thirsty big displacement naturally aspirated engines toward smaller thriftier ones, automakers are increasingly employing turbochargers and superchargers to make more power from less fuel.
Both devices serve as a “replacement for displacement” by helping cram the same amount of air a bigger engine would naturally inhale into a smaller engine so they can make the same power when the driver’s foot hits the floor.
Oxygen, it turns out, is way harder to get into an engine than fuel. (This is also the purpose nitrous-oxide systems serve in the go-fast aftermarket.) Let’s take a fresh look at the relative merits of turbocharging versus supercharging.
A supercharger is driven from the engine’s crankshaft by a belt, shaft, or chain whereas turbochargers obtain their power from a turbine which harvests energy from the engine’s exhaust gases. Turbochargers. In simple terms, a turbo is an air pump that enables more air to be pumped into the engine at higher pressure.
“Supercharger” is the generic term for an air compressor used to increase the pressure or density of air entering an engine, providing more oxygen with which to burn fuel. The earliest superchargers were all driven by power taken from the crankshaft, typically by gear, belt, or chain.
A turbocharger is simply a supercharger that is powered instead by a turbine in the exhaust stream. The first of these, dating to 1915, was referred to as turbosuperchargers and were employed on radial aircraft engines to boost their power in the thinner air found at higher altitudes. That name was first shortened to the turbocharger and then to the turbo.
Each can be used to increase power, fuel economy, or both, and each has pros and cons. Turbochargers capitalize on some of the “free” energy that would otherwise be completely lost in the exhaust.
Driving the turbine does increase exhaust backpressure, which exerts some load on the engine, but the net loss tends to be less by comparison with the direct mechanical load that driving a supercharger involves (the biggest blowers powering a top-fuel dragster consume 900 crankshaft horsepower in an engine rated at 7,500 total horsepower).
But superchargers can provide their boost almost instantly, whereas turbochargers typically suffer some response lag while the exhaust pressure required to spin the turbine builds.
Clearly, a top-fuel dragster trying to run the quarter in four seconds has no time to waste waiting for exhaust pressure to build, so they all use superchargers, while vehicles tasked with boosting a company’s corporate average fuel economy (CAFE) can’t afford to squander precious horsepower on blowers, so they mostly use turbos.
But with the rise of mild hybridization and 48-volt electrical systems, you can expect to see greater use of superchargers driven by freely recuperated electricity stored during deceleration and braking.
Mercedes-Benz’s new M256 six-cylinder now arriving in vehicles like the CLS 450 and GLE 450 uses just such a system, as does the similarly sized and configured range-topping engine in the new Land Rover Defender.
Above we noted that the amount of oxygen that an engine can “breathe” is the limiting factor as to how much power it can produce because fuel-injector technology is more than capable of supplying as much fuel as can possibly be burned with the amount of oxygen in the cylinder.
Naturally aspirated engines operating at sea level get air at 14.7 psi, so if a turbo or supercharger adds 7 psi of boost to an engine, then the cylinders themselves are getting roughly 50 percent more air and should theoretically be able to produce about 50 percent more power.
It doesn’t usually work out that way. Compressing intake air adds heat, which along with the added pressure increases the likelihood of engine-damaging pre-detonation or “ping,” so the timing often has to be retarded somewhat.
This can limit the amount of time the fuel has to completely burn and hence erodes some of the power gains. Most modern engines running turbos and/or superchargers also include intercoolers to help remove some of the heat added by the turbo or supercharger. In the end, the typical expectation is that adding 50 percent more air yields 30 to 40 percent more power.
When they’re working, turbos and superchargers mostly help to burn more gas, but when they’re bolted to an engine that would otherwise be too small to adequately meet the vehicle’s needs in terms of acceleration or when towing, etc., they help save gas during the low-power cruising that comprises most of our driving.
One of the ways this happens is by reducing the pumping losses that occur when a big-displacement engine is running at five percent throttle or less it must work hard to suck air past a mostly closed throttle. That same amount of power might require a 20 percent throttle opening on the smaller engine, which results in less pumping work.
This is why many newer cars don’t create enough vacuum to run power brakes, climate-control systems’ blend-air doors, etc., and either features auxiliary vacuum pumps or use electric controls for these items.
Turbos tend to outperform crank-driven superchargers on the critical FTP75 fuel-economy test that determines the window-sticker mpg numbers and a corporation’s CAFE rating, so turbos are found on more mainstream vehicles ranging from the $21,240 Ford EcoSport 1.0-liter turbo to any of the four turbocharged engine offerings in the Ford F-150 pickup.
Meanwhile, as this list of every supercharged vehicle available in the U.S. indicates, superchargers are mostly fitted to high-performance vehicles. Of course, all Volvos equipped with 2.0-liter twin-charged engines like the XC60 and XC90 T6 and T8 models feature both a turbocharger and a supercharger.
This design capitalizes on the strengths of each supercharger boost at low rpm supplies pressure until the larger turbo spools up, at which point the supercharger is declutched from the crankshaft so as not to rob power.
Twin-turbo just means that there are two turbochargers. These can either work independently (as is often the case on vee-configuration engines, where there are separate turbos functioning on each side of the engine), or in series.
When they’re used in series, a small and a large turbo are paired, in which case the small one spools up quickly to reduce turbo lag, then as exhaust flow increases, the larger turbo begins supplying the boost.
Note that some refer to the former as a Biturbo (Mercedes badges many of its AMG cars Biturbos) and the latter as a twin-turbo, but we don’t make this distinction. Naturally, quad-turbo means there are four of them, as in the Bugatti Chiron.
Its big W-16 engine employs two pairs of sequential turbochargers. For years most turbocharged vee engines hung the turbos off the exhaust manifolds on the outboard side of the engine, with intake air entering in the valley of the vee.
Lately, there’s been a push toward reversing that and feeding intake air into the outboard sides of the vee with the exhaust plumbing and turbos nestled inside the vee. This has the advantage of greatly shrinking the overall size of the engine and, with proper hood ventilation, can result in lower underhood temperatures.
Each of these power-boosting technologies has advantages and disadvantages, but the most obvious difference from behind the wheel is a slight delay in response to your right foot in a turbocharged car, especially when you push deep into the throttle.
That’s because the turbocharger requires a moment to “spool up” before delivering its burst of additional power, it takes a second for exhaust heat and pressure to increase enough to spin the turbo after you push on the gas pedal. It’s called “boost lag” or “turbo lag” for obvious reasons.
By contrast, a supercharger has no lag; because its air pump is linked directly to the engine’s crankshaft, it’s always spinning and instantly responsive. The power boost it provides, and therefore the engine response you feel through the seat of your pants, increases immediately in direct proportion to how far you press the accelerator.
While the turbo’s primary drawback is boost lag, the supercharger’s is efficiency. Because a supercharger uses the engine’s own power to spin itself, it siphons power more and more of it as the engine revs climb. Supercharged engines tend to be less fuel-efficient for this reason. For developing mega power with instant kick-you-in-the-back throttle response, however, supercharging rules.
Each can be used to increase power, fuel economy, or both, and each has pros and cons. But superchargers can provide their boost almost instantly, whereas turbochargers typically suffer some response lag while the exhaust pressure required to spin the turbine builds.
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.
A turbocharger works with the exhaust system and can potentially give you gains of 70-150 horsepower. A supercharger is connected directly to the engine intake and could provide an extra 50-100 horsepower.
Using the science of compressor maps and some idea of the size and rpm range of your engine, you can add virtually any turbo to any engine. The trick is the availability of the maps and the A/R ratios of the turbine housing and the sizes of the turbine wheels.
Well, more power means more energy output per second. This means that you have to put more energy when you use it. So, you must burn more fuel. In theory, that means an engine with a turbocharger is no more fuel-efficient than one without.
Yes. You can use both. The concepts of superchargers and Turbochargers are slightly different.
Twin-scroll turbochargers offer higher levels of gas-flow efficiency, reduced turbo-lag, and allow engines to be tuned for slightly more power than the single-scroll variety. Even the BMW inline-6s no longer need a pair of turbos, relying instead on a single twin-scroll system.
Here are the most effective ways we’ve found to boost your truck’s power.
A turbocharger relies on a vehicle’s exhaust to spool up a turbine to power a compressor. The compressor then pulls in and feeds more air to an engine. On the other hand, a supercharger depends on the engine to rotate. It can be gear-driven or belt-driven, but the engine powers the unit in the end.
Supercharging Pros: Produces significantly more horsepower than turbocharging. A quick solution to boosting power in larger displacement engines with more cylinders. No power lag as is seen with turbocharging; power delivery is instantaneous.
A turbo is more efficient than a supercharger since your engine does not need to work harder to power the turbo. Because a turbo is not connected directly to the engine, it can spin much faster than a supercharger.
A supercharger is an air compressor that increases the pressure of air supplied to an internal combustion engine. This aids in higher power output as the engine gets more oxygen in each of its intake cycles and helps it to burn more fuel.
If you don’t have a turbo, your engine will start and run without one, but make sure the oil line is not connected to the engine.
Unlike superchargers, many modern cars incorporate turbochargers as a standard part. Turbocharged vehicles are much more common in the United States, mainly due to the fact that they’re powered by exhaust gases that were not being used until now.
Surprisingly enough, peeking inside its engine bay won’t shed any light on the matter, and that’s because the Mustang has a Hellion sleeper twin-turbo system. Even so, you can get an entry-level twin-turbo setup for the same money as a supercharger, and the horsepower gain is going to be similar, if not superior.
This causes what is commonly referred to as turbo lag. Turbochargers are cheaper than superchargers, more efficient, and less impactful on your engine. One of their downfalls though is their lack of efficiency and power boost at low RPMs.
Turbos have amazing efficiency because it takes no horsepower to make power as a supercharger needs to use power to make power. Some key advantages turbochargers have over superchargers are better fuel economy and a longer lifespan. But where the turbo falls short is turbo lag.
The Dodge Hellcat has a supercharger, which is already crazy, but it also has a manual transmission. With those turbos and superchargers, it makes a ridiculous amount of horsepower, and that 800 hp figure is with the car on its lowest power level, just to run the car on regular pump gas.
The most obvious advantage of having a turbo engine is that it gives you more power output due to its intake of air, meaning that you’re going to have a much faster and more powerful ride. An engine fitted with a turbo is much smaller and lighter compared to an engine producing the same power without a turbocharger.
Supercharger produces significantly more horsepower than turbocharging. A quick solution to boosting power in larger displacement engines with more cylinders. No power lag as is seen with turbocharging; power delivery is instantaneous.
From an efficiency standpoint, the turbocharger has an advantage. It takes wasted exhaust and turns it into something useful. Meanwhile, a supercharger won’t do this and acts more like a naturally aspirated engine. However, with a turbocharger comes lag.
Unfortunately, consumers don’t know the full, long term effects turbochargers have on their engine. Superchargers are arguably more reliable than turbochargers. They’re easy to install and maintain.
