Compared to other technologies we use every day, it seems like car engines haven't really changed much. The engine in an old Ford Model T has plenty in common with the engine in a 2011 Ford Fusion, but it's doubtful Alexander Graham Bell would know what to do with an iPhone. While communications technology has changed drastically, car engines use the same basic principle: The combustion of air and fuel to create rotational force and move a car.
But while the same basic principles that drove the first car engines are still used today, modern car engines have evolved to meet the power and efficiency needs of today's drivers. Think of older car engines as wolves and modern car engines as dogs. They're share the same heritage and have similar characteristics, but one does just fine in everyday modern situations, while the other just couldn't adapt to living in a city or suburb.
Before we talk about how modern car engines are different from older ones, you need to understand the basics of how a car engine works. Basically, gasoline and air are ignited in a chamber called a cylinder. In the cylinder is a piston that gets moved up and down by the gasoline/air explosion. The piston is attached to the crankshaft. As the piston moves up and down, it makes the crankshaft rotate. The crankshaft goes out to the transmission, which transmits that power to the car's wheels. Sounds simple, right? With modern engines the basics still apply, but there's a lot more to think about.
Your basic gasoline car engine isn't all that efficient. Of all the chemical energy in gasoline, only about 15 percent gets converted into the mechanical energy that actually moves the car. The EPA says over 17 percent of the energy is lost as the engine idles, and a whopping 62 percent is lost in the engine due to heat and friction.
Modern engines have a number of technologies in place to make them more efficient. For example, direct injection technology, which mixes the fuel and the air before they're put into the cylinder, can improve engine efficiency by 12 percent because the fuel burns more efficiently [source: U.S. Department of Energy]. Turbochargers, which use compressed air from the car's exhaust system, compress the air that's used in the combustion cycle. The compressed air leads to more efficient combustion. Variable-valve timing and cylinder deactivation are technologies that allow the engine to use only the fuel it needs, increasing efficiency.
There's a common misconception that efficient engines are underpowered engines. Keep reading to learn how modern engines out-muscle their older counterparts.
People are more concerned with fuel economy now than when cars were new, but they're also more concerned with engine power. After all, the first cars only had horses to keep up with. Now cars are driven on freeways. Modern cars are also a lot heavier than early cars, because they're stuffed with safety features and accessories. Today's car engines have a lot more work to do. They're carrying heavier loads at faster speeds.
Even with their increased efficiency, today's engines are more powerful than their predecessors - even compared to engines that are just a few years old. In 1983, the Chevrolet Malibu had a 3.8-liter V-6 engine that made 110 horsepower. In 2005, it had a 2.2-liter inline four cylinder making 144 horsepower. The 2011 Malibu has a base 2.4-liter four cylinder making 169 horsepower. Buyers can also get a 3.6-liter V-6 that makes 252 horsepower. Even though the V-6 on the 2011 Malibu is smaller than the V-6 offered on the 1983, model, it makes 146 more horsepower. Even the current four-cylinder engine on the Malibu makes 59 more horsepower than the 1983 model's V-6.
Since modern engines make more power than older engines, you'd expect them to be larger. But if you look at the example of the Chevrolet Malibu we used on the previous page, you'll notice that while engine power increased, engine size decreased.
The incredibly shrinking engine in today's cars can be chalked up to improved efficiency. Car makers have learned that you don't have to make the engine bigger to get the power consumer's want. You just have to make the engine work smarter. The same technology that helps modern engines work more efficiently also means that modern engines can make more power without needing a larger package.
The best example of this is Ford F-Series trucks. Long the best selling truck (and often the bestselling vehicle, period) in America, the 2011 Ford F-150 is a textbook example of a smaller engine doing the same work as a larger one. The 2011 F-150 has an optional 3.5-liter V-6 engine that makes 365 horsepower. The available 5.0-liter V-8 makes 360 horsepower. As a rule of thumb, a bigger engine will still make more power than a smaller one. The F-150 has an available 6.2-liter V-8 that makes 411 horsepower, which pretty much blows the 3.5-liter V-6 out of the water. But, the fact that a V-6 engine can compete with a smaller V-8 in terms of power is pretty impressive. As consumers call for better fuel economy, expect to see smaller engines doing the work that was once reserved for monster V-8s.
One major difference between modern car engines and older car engines is that modern car engines don't work as hard. In an old V-8 engine, all eight cylinders were firing, no matter if the car was idling or accelerating as fast as it could. Also, all eight cylinders were getting the same amount of fuel, regardless of how much work the engine was doing at the time.
Today's engines have technology that makes them work smarter. Cylinder deactivation is a system that allows some cylinders in an engine shut down when they're not needed, like when the car is idling or cruising. When more power is needed, those cylinders "wake up" and help out. Cylinder deactivation helps engines work more efficiently, since it means the engine only uses the fuel it needs and only extends the effort required for the job at hand.
Variable-valve timing and lift is another technology that helps modern engines work smarter. Without this system, the engine's valves open for the same amount of time and the same distance no matter how hard the engine is working. That wastes fuel. With variable-valve timing and lift, the valve openings are optimized for the type of work the engine is doing. That helps the engine use less fuel, and work smarter.
Modern engines have a lot of technology that helps use less fuel while making more power than older engines, but they have one last thing that older engines just didn't have: partners.
Today's car engines are not only sophisticated technological achievements, they're partnered with other high-tech components that help them do their jobs better. A four-or five speed transmission used to be cutting-edge, but today's engines are partnered with transmissions with seven and even eight speeds. The more speeds a transmission has, the better it's able to mesh with engine power, making the whole drive train run more efficiently. Or, if eight speeds aren't enough, modern engines are partnered with Continuously Variable Transmissions (CVTs). CVTs have an infinite number of gear ratios, making them able to transmit the engine's power to the wheels in the most efficient way possible.
In hybrid cars, modern engines get help from electric motors powered by battery packs. While the electric motor can power the car at slow speeds, or run accessories when the car is stopped, it can also kick in to generate extra power when it's needed, like when a car is accelerating hard. Having an electric motor as a backup means that the car's engine can be a bit smaller and less powerful, which saves fuel. In some cases, though, car companies are combining electric motors with big, powerful engines for a performance punch.
For more information about modern car engines and other related topics, follow the links on the next page.
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- General Motors. "Chevrolet Malibu Media Archives." (June 1, 2011) http://archives.media.gm.com/division/2003_prodinfo/03_chevrolet/03_malibu/index.html
- LaBarre, Katie. "2011 Ford F-150 Review." U.S. News Cars. (June 1, 2011) http://usnews.rankingsandreviews.com/cars-trucks/Ford_F-150/
- U.S. Department of Energy. "Energy Efficient Technologies." (June 1, 2011) http://www.fueleconomy.gov/feg/tech_adv.shtml