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We tell you how an Atkinson Cycle engine works and helps save gas.

The Atkinson Cycle engine is frequently touted by the companies selling them but never fully explained. It is commonly seen in hybrid vehicles and specific gasoline-only variants. The engine is more fuel-efficient than a typical gasoline motor, to put a long tale short.

Although the bottom line is all that counts when you buy a car, it's still a good idea to understand how the Atkinson cycle differs, so you won't be inundated with incorrect information from people who claim to be experts.

Despite being a relatively old technology, the Atkinson-cycle gasoline engine has become popular again because of how much fuel it can save. In addition, it works perfectly with hybrid vehicles, as the electric motor helps to make up for Atkinson's drawbacks.

Related: These 10 New Cars Have The Best Fuel Economy In The Industry

You need to be familiar with engine operation to comprehend Atkinson. Each cylinder of an engine has a piston inside; a four-cylinder machine has four, and a V6 or V8 has six or eight cylinders placed in pairs to form "V" shapes.

How your legs turn the pedals on a bicycle is comparable to how these pistons travel up and down to turn a central crankshaft. The crankshaft's rotation eventually turns the wheels. Gasoline is sprayed into the engine, where it powers the pistons before being ignited by the spark plug.

Each cycle involves the piston moving four times: downward to suck in gasoline vapor, upward to compress it, downward when the vapor ignites and explodes, and upward to push out the exhaust. During this, valves open and close precisely at the appropriate moments to let gasoline in and exhaust out.

The same principles govern an Atkinson-cycle engine, but with a twist. When the piston rises during the compression stroke of a typical machine, the intake valve remains closed, building pressure inside the cylinder. The valve remains open a little longer in an Atkinson-cycle engine.

As a result, fuel economy is increased because the piston doesn't have to exert as much force to overcome friction due to the cylinder's reduced pressure. Some gasoline vapor escapes into the intake manifold through that open valve, but nothing is lost because it is drawn back the next time the valve opens.

Low engine speed power reduction occurs due to the combustion chamber not being filled with air. The Atkinson Cycle motor is more effective because it reduces the stress on the piston during the compression stroke by giving it more room to breathe, resulting in a lower power engine than a typical Otto cycle.

The combustion chamber has less air; thus, the injector doesn't need to add as much fuel as before. Remember that the engine needs to run on its power to maintain the combustion cycle. An Atkinson cycle engine adjusts the combustion process to reduce the parasitic power loss that most standard engines encounter in exchange for a little more power.

When James Atkinson created his first engine in 1882, it used a complex mechanical system that altered the piston's cycle's travel distance. Modern engines work their magic using electronics and software. Like Atkinson's mechanical invention, keeping the valve open longer raises the cylinder's displacement, but the piston's travel distance is unaffected.

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hat are the drawbacks of all of this, then? The Atkinson cycle increases fuel efficiency but has a lower power output than a standard engine. It gives you enough power for comfortable low-speed driving or steady cruising, but not the quick acceleration you want.

It hasn't been used in most conventional automobiles because of this, but it's perfect for a hybrid system. This utilizes an electric motor in addition to the gasoline engine and, depending on the situation, alternates between running on gasoline, electricity, or a combination of the two.

When necessary, the Atkinson-cycle gas engine can handle moderate driving, but when more power is required, the electric motor engages in increasing the engine's output. Continuously variable transmission (CVT)-based hybrids maintain the engine at its ideal rpm for power and efficiency by using pulleys and a belt in place of gears.

The concept of small-displacement turbocharged engines, like Ford's EcoBoost engines, is "power only when needed." Under moderate throttle, these smaller engines use less gasoline than larger ones, but the turbo comes on to deliver more power. However, when the turbo is engaged, these can become thirsty, whereas the electric motor in a hybrid requires no fuel to boost energy.

Related: This Is The Best Hybrid Car To Buy In 2022

However, not everyone like hybrid vehicles, so Toyota added a new engine to its 2016 Tacoma pickup truck to provide another alternative. While power is required, like when accelerating, the engine runs typically. However, at a constant speed, when maximum capacity is not needed, the valve timing switches to the Atkinson cycle to conserve gasoline; the driver is unaware of the switch because it is smooth.

The engine also has two fuel delivery systems: direct and port injection. It can use either one or the other depending on the power required—from cold starting to towing—while maintaining optimal economy. It's one of several fuel-efficiency techniques automakers use, including cylinder deactivation, multiple-speed gearboxes, lightweight design, and enhanced aerodynamics. So engineers will be occupied as long as fuel consumption is a problem.

Sources: Toyota, Chrysler, Chevrolet, Wikimedia Commons

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