Techsplanations: Turbocharger

Turbo chargers have been around the auto industry for decades, typically used to boost the performance of already powerful engines. But today, the turbo is showing up in cars, SUVs and trucks of every stripe and price to boost fuel economy.

The Hyundai Veloster, Chevy Malibu, Chevy Sonic and Ford F150 pickup are all sporting turbos to make small fuel efficient engines perform more like bigger, thirstier ones. If you are interested in a new car that comes with a turbo, and you have never driven or considered one before, here is what you should know before signing on the bottom line.

What is it?

A turbocharger - or just "turbo" for short - is a mechanical device that boosts engine power. All car engines require three things to create the explosions that power them: air, fuel and ignition. Turbocharged engines are called "forced induction" engines, because the turbo forces more air into the engine. This allows it to burn more fuel with every revolution, making the engine more powerful than one without a turbocharger, which are known as "naturally aspirated engines." Turbos allows car manufacturers to put replace bigger engines with smaller ones, such as dropping a V-6 for a four-cylinder engine or replacing a V-8 with a V-6. The only thing consumers notice is improved fuel economy.

How does it work?

It's actually pretty simple. The turbocharger is attached to the engine near the exhaust manifold, so that gasses can pass through the turbo before they go into the pipes that carry the exhaust back to the muffler and tailpipe. The exhaust gasses pass through a turbine in the turbocharger, spinning it at thousands of revolutions per minute. The turbo pressurizes the fresh air that's headed into the engine. The real beauty of the system is that it doesn't require any extra energy to compress the air headed into the engine.

To simplify it a bit more, think of a turbocharger as a pair of big fans. The exhaust gas coming out of the engine spins one of the fans. That's connected to the second fan, which blows fresh air back into the engine. Since the air going into the engine is pressurized, more of it can be crammed into the same volume in the cylinders than a naturally aspirated engine. So the engine control computer is able to add more fuel to the cylinders, to create bigger explosions, which translates into more power. This means the engine only produces more power when the driver wants it.

Why would I want it?

Easy: Better fuel economy with no sacrifice in power. Most of the time you're driving your car you don't need lots of power. A car only uses about a third of its maximum horsepower to drive on the freeway, and most of the time you're driving in the city you're actually decelerating, braking or stopped. At these times, the turbo is off, so the engine consumes less fuel than a bigger, naturally aspirated engine.

But when it does come time to accelerate, the turbocharger allows the smaller engine to produce enough power to feel like a much bigger engine and propel the car smoothly up to speed.

Is there any downside?

In earlier eras, turbochargers got a bad rap for being prone to failure. They also developed a reputation for having "lag," a delay between the driver pressing on the accelerator and the turbocharger producing its full effect. Both problems have been largely consigned to history, as modern materials and manufacturing techniques have made turbochargers much more durable. Lag has been mostly eliminatd, but you need to test drive the car, of course, to see for yourself. The degree of lag varies from car to car.

The one downside to turbocharged engines is that they do have extra parts compared to naturally aspirated engines, which can make them a bit more expensive to manufacture. This usually translates to a slightly higher price for turbocharged trim levels of the same model.

What vehicles offer it?

Volkswagen has long offered turbocharged four-cylinders in most of its lineup - the current 2.0-liter turbo engine with direct injection makes 200 horsepower in the 2012 Beetle. That powerplant is also offered in the GTI, Jetta GLI, and Tiguan, among other VW and Audi

Ford has gotten into turbocharging more recently, and in a big way. Its "EcoBoost" line of engines all incorporate turbochargers, along with direct injection technology, offering better fuel economy from smaller engines. Ford's flagship F-150 pickup features an optional 3.5-liter EcoBoost V6 that outperforms its huge 5.0-liter V8, offering more horsepower and torque, plus better fuel economy.

Check out our Techsplanation article on Direct Injection.

More stringent fuel economy regulations have resulted in many more turbocharged vehicles being introduced in recent years. Other manufacturers that offer turbocharged models include BMW, GM (in its Chevrolet Sonic and Cruze, among others), Hyundai, Kia, Mitsubishi, Subaru and Volvo.

Bottom line

Turbocharged engines are a winning proposition for consumers. Providing greater efficiency and more power, turbocharing translates to smaller engines with better mileage with no sacrifice in performance.

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