Turbocharged Engines Offer Performance, Efficiency

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The old saying “good things come in small packages” never rang so true. I had just climbed out of the new Alfa Romeo 4C and the goofy grin on my face was over the top; so much so that my friends were wondering if exhaust fumes got into the cabin. Alfa’s exotic little sports car, with its turbocharged engine and rear-wheel drive setup, provides just about as much excitement and entertainment as a car is possible of creating.
Sure I’ve driven faster and more powerful cars. The Dodge Charger SRT Hellcat for instance, with a massive 6.2-liter supercharged V8 engine that produces an outrageous 707 horsepower. Or the recently reviewed all-new 2016 Cadillac CTS-V, which almost qualifies as a sleeper thanks to tastefully designed sheet metal that conceals another supercharged 6.2-liter V8 (this one cranks out a ridiculous 640 horsepower).

2015 Alfa Romeo 4C (CARFAX, Inc.)

2015 Alfa Romeo 4C (CARFAX, Inc.)

The Alfa Romeo 4C takes an entirely different, but related, approach. Applying the “less is more” philosophy, Alfa Romeo is using technology to create engineering masterpieces that would have been impossible for a mass-produced street car just a few years ago. Challenging the “there is no replacement for displacement” axiom, the 4C uses its small footprint and a tiny turbocharged engine to provide driving performance that’s nearly on par with larger, V8-powered sports cars.

Naturally Aspirated vs. Forced Induction

Traditional naturally aspirated engines draw air through an intake and into an engine’s cylinders where it atomizes the fuel being simultaneous squirted in from an injector. The mist is then compressed and ignited by a spark, which causes it to combust and violently push a rod that turns the engine’s crankshaft. The crankshaft spins the transmission that eventually rotates the vehicles wheels. The explosion also generates the energy to open a valve that allows more air to be sucked into the engine, at which point the injector spits more fuel, the spark plug ignites and the cycle repeats itself until you turn off the motor.

Rather than simply relying on the engine to pull all the air that it needs for combustion, forced induction engines increase the oxygen drawn into the cylinder by compressing the air with either a turbocharger or supercharger. In some cases, such as with newer Volvo vehicles, supercharging and turbocharging are used together on the same engine. When you increase the air available for combustion you can also increase the amount of fuel, resulting in a bigger, more powerful explosion and significantly more power through each rotation of the engine.

Dodge Charger SRT Hellcat (CARFAX, Inc.)

2015 Dodge Charger SRT Hellcat (CARFAX, Inc.)

Forced induction engines have long been the go-to of high horsepower muscle cars, like the aforementioned Charger Hellcat and Cadillac CTS-V. Both vehicles use a supercharger, which allows the already massive 6.2-liter engines to suck outrageous amounts of air and burn incredible amounts of fuel for ground rattling explosions and audacious power.

The forced induction formula also works in reverse, where manufacturers can build significantly smaller engines that create equal horsepower and torque to their naturally aspirated counterparts. Typically, these smaller turbocharged engines also consume less fuel, and they’re often lighter and produce fewer emissions than a naturally aspirated engine that makes the same power. In short, less is more with forced induction.

Using this formula, automakers began swapping or substituting massive V8s for smaller turbocharged V6 engines. By the same token, many cars that used to come with a naturally aspirated V6 now have a tiny turbo-four under the hood. Even in the cases where the smaller engine’s power is reduced versus the outgoing V6, overall performance is typically on par or better, thanks to the weight savings a smaller engine provides.

Four is the New Six

2015 Alfa-Romeo 4C (CARFAX, Inc.)

2015 Alfa-Romeo 4C (CARFAX, Inc.)

The Alfa Romeo 4C is powered by a miniscule turbocharged 1.7-liter four-cylinder engine, but the powertrain is only a part of what makes the 4C such a fantastic driver’s car. Made from space-age materials, Alfa has created a vehicle that weighs less than 2,000 pounds without and fluids and 2,500 pounds when ready to roll. When you put the whole thing together, the result is a vehicle that rips from 0 to 60 mph in 4.1 seconds. Thanks to a well-balanced chassis and low center of gravity, the 4C also handles like the tires are magnetically attached to the road.

As amazing as that is, the 4C’s greatest performance figure is not how quickly it sprints to the end of the quarter mile or how graciously the little coupe rips around the racetrack, but the fuel economy it gets.

For many, gas mileage has become the new performance standard. Yes, fuel prices have plummeted recently, but it wasn’t very long ago that a gallon of gasoline cost more than a 6-inch sub sandwich at the local strip mall. The feisty Alfa Romeo 4C earns 24 mpg city and 34 mpg highway. Impressive for any car, but when you consider that the 4C can hit 160 mph, the numbers almost defy logic.

Unfortunately, the little Alfa Romeo is completely impractical for most of us. Cargo space is terribly limited and ingress and egress is an absolute disaster unless you’re under 25 years old or practice yoga for three hours a day. The good news is that the tiny-turbo formula is incredibly useful for turning more utilitarian vehicles into excellent performing machines that simultaneous achieve incredible fuel economy and noteworthy performance.

2016 Honda Civic (CARFAX, Inc.)

2016 Honda Civic (CARFAX, Inc.)

The 2016 Honda Civic’s new 1.5-liter turbocharged engine produces a very healthy 174 horsepower and 162 pound-feet of torque, and it helps the Civic achieve 31/42 mpg city/highway. The Civic’s spacious interior earns it a midsize EPA classification, and the 15.1 cubic feet of cargo space is among the best in class. Similar to the 4C, the Civic is fit and trim, weighing less than 3,000 pounds even in the fully loaded Touring trim.

2016 Lexus IS 200t (CARFAX, Inc.)

2016 Lexus IS 200t (CARFAX, Inc.)

Luxury cars are also getting the tiny-displacement turbocharged makeover. Last year, Lexus dropped the 2015 NX 200t crossover on us. The Lexus-built 2.0-liter turbo-four is an absolute engineering marvel, creating 235 horsepower and 258 pound-feet of torque. The engine is powerful enough to blast the loaded-up SUV from 0 to 60 mph in 7.2 seconds, and it helps the NX achieve a noteworthy 22/28 mpg city/highway.

The 2.0-liter Lexus turbo found its way into the new 2016 Lexus IS 200t. This 241-horsepower luxury sedan is incredibly fun to drive and has plenty of room for four adults. All this and somehow the IS 200t still manages 33 mpg on the highway.

Turbo or Not Turbo, That is the Question

There are some draw backs to the tiny turbo formula. While not as bad as earlier applications, turbo engines often take a second or so to “boost.” In simple terms, the turbocharger needs to pull energy from the car’s exhaust, which spins a fan to compress the air. On today’s cars this process happens in 10ths of a second, but that “turbo lag” still results in a lack of immediacy when you mash the throttle. Sophisticated turbocharging systems help eliminate the lag, but in cars like the Lexus IS 200t I recently drove, that initial slog is still present. The result is a car that offers incredible midrange performance, but stumbles a little off the line or when you floor the pedal in traffic.

2016 Lexus IS 200t (CARFAX, Inc.)

2016 Lexus IS 200t (CARFAX, Inc.)

The other downside is that forced-induction engines often require the use of premium unleaded fuel. Higher octane fuel slows the ignition process enough to avoid engine “knock,” which can result in engine damage and failure if regular unleaded is used. It is certainly worth nothing that not all turbocharged engines require high-test fuel, many of Ford’s new EcoBoost engines run on regular unleaded.

While this discussion of today’s forced induction engines is in no way exhaustive (pun intended), I do hope that it clears up some of the questions you may have when shopping for your next vehicle. Do plenty of research, ask lots of questions and schedule an extended test drive before committing your hard-earned money. I can list pros and cons all day, but you are the only one who can decide if your next vehicle will be naturally aspirated or turbocharged.

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By | 2018-02-13T20:52:57+00:00 February 23rd, 2016|Car Tech|1 Comment

One Comment

  1. linda Prin June 17, 2016 at 10:39 am - Reply

    It sounds like the Naturally Aspirated engines are really incredible as far as speed goes. I am not a car person, but my brother is and I’m trying to get acquainted with supercharged models features. I’ll have to ask him which he prefers of naturally aspirated or forced induction. Thanks for the tutorial

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