Power and efficiency

ENGINE power and fuel efficiency may seem like two opposing features of a modern day car engine. These, however, are becoming the goal of most car manufacturers in creating their cars.

A powerful engine that can deliver great speeds and handle heavy- duty requirements is still one of the top car features that appeal to most car buyers. This captivation with speed and power was highlighted in the 1960s and 1970s when car manufacturers introduced muscle cars with bigger internal combustion engines that could handle the torque and horsepower needed for these feats.

Horsepower, which dictates how much work or power can be generated in a given time, and torque, the twisting force, that can determine performance in changing gears and moving parts within the engine are speed components that come at more than a financial cost.

These engines burn more fuel per mile, resulting in larger amounts of combustion. What car manufacturers realized then was that these super engines that they created resulted in more engine displaced and decreased fuel efficiency.

Yourmechanic.com, a resource for anything mechanic, defines engine displacement simply as the combined swept volume of the pistons (moving components in the cylinder) inside the cylinders of an engine. It is calculated from the bore (diameter of the cylinders), stroke (distance the piston travels) and a number of cylinders. Displacement is an important factor, as it has a direct impact on an engine’s power output.

Over the years, as more car owners aimed for speed and preferred higher horsepower, automobiles consumed more fuel. Car manufacturers responded then by trying to create more fuelefficient engines during the 1970s and 1980s but these resulted in a decrease of power. There is obviously a connection between power and fuel efficiency. To this day car manufacturers are tackling this need.

With modern technology, it’s becoming easier to balance performance and fuel economy.

While garnering mixed reviews, turbochargers can be the link between speed and fuel efficiency. Turbochargers have been popularly intended as an alternative to the stress the internal combustion engines create to the environment to follow government guidelines on emission.

Turbocharger is a device that is used to boost engine power. It forces more air into the cylinders. It uses a turbine to create hot gasses from the exhaust that works a compressor that pushes air into the cylinder to increase combustion. Before turbochargers, the only option to increase speed was to add more cylinder to the engine. Turbochargers can make such a difference that with a four-cylinder engine it can produce as much power as a sixcylinder engine, but use less fuel when driven gently.

Some argue, however, that turbochargers may not be as fuel efficient as they are thought to be. This quite wavering performance of turbochargers is pushing car manufacturers to look at other ways to increase performance and fuel efficiency.

In The Economist, a story titled “The incredible shrinking machine” noted that internal combustion engines are getting smaller but not consequentially losing power.

Car manufacturers are now experimenting with lighter and smaller engines with turbochargers. These engines that use light materials are built to handle high temperature. With this new update, it is expected that a phenomenon called “turbo lag” that reduces acceleration will be prevented.

However, Green Car Reports, a Web site focusing on environment- friendly vehicles, concluded, after a series of tests, that “with the latest generation of small turbocharged engines replacing larger variants, the real-world gas mileage improvement is nowhere near that of the on- paper advantage in official economy tests.”

Apart from turbochargers, engine makers are looking at other parts of the engine to increase fuel efficiency and power. These are the nuts and bolts — the intricacies that may be put under stress with various driving conditions. Among these is the fuel injection cylinder, as noted in The Economist article, which can be updated to inject petrol at high pressure directly into the cylinder. A takeoff from the previous method of having fuel be mixed with the air before it reaches the cylinder. The new fuel injection cylinder will give fuel more evenly to the cylinder contributing to engines that produce less pollution.

Another is variable valve timing. The engine’s management system controls the opening and closing of the valves that let air into the cylinder and exhaust gases out.

“A process called cylinder deactivation is also being explored for small engines,” The Economist article said. “As its name implies, this turns some cylinders off to save fuel when a car’s engine is being used lightly. Cylinder deactivation is already employed in certain large engines.”