How Much Do You Know About Four-Stroke Engines?

Annette

A four-stroke engine is otherwise known as a ______ engine.

The four-stroke engine is otherwise known as the four-cycle engine. It's an internal combustion engine in which the piston completes four seperate strokes.

What is the first stroke of a four-stroke engine​?

Intake is the first stroke of a four-stroke engine. This is also known as induction or suction. It begins with the piston in the top dead center and ends at the bottom dead center.

What is the second stroke of a four-stroke engine?

The second stroke of a four-stroke engine is compression. It begins just at the end of the intake stroke and ends top dead center. This is when the piston compresses the air-fuel mixture.

What's the third stroke of the four-stroke engine?

This is where the combustion engine gets its name. The third stroke is combustion, otherwise known as power or ignition.

What is the last stroke of a four-stroke engine?

The last stroke of the four-stroke engine is exhaust. This is also known as outlet. In the exhaust stroke, the piston turns from bottom dead center back to top dead center.

Who began the first internal combustion engine production company?

In 1864, Otto and Eugen Langen founded the first internal combustion engine production company. It was titled NA Otto and Company.

Who was the technical director of the first internal combustion​ engine company?

Gottlieb Daimler is a popular name in motorcycle engine mechanics. He and Wilhelm Maybach helped to create the first internal combustion engine that compressed the fuel mixture​ prior to combustion, leading to better efficiency. By the time Daimler joined, NA Otto and Company was renamed Deutz Gas Engine Manufacturing Company.

What was the first car to employ the Otto engine?

The Daimler Reitwagen was the first car to use the Otto combustion engine. It used a hot-tube ignition system and fuel known as Ligroin.

Otto's company, Deutz, created the first ______.

Otto's company, Deutz, is credited with creating the first carburetor and electric ignition system. The company was located in Germany, a hotbed for auto innovation.

As air/fuel is being compressed, a _____ ignites the mixture.

As the air/fuel mixture is being compressed, it's an electric spark which ignites this mixture. This occurs close to top dead center at a low rpm.

As rpm rises, the speed of the flame front does what?

As engine rpm rises, the speed of the flame from stays the same. This allows the spark point to advance earlier in the cycle, allowing the charge to combust before the power stroke begins.

A compressed-charge engine has an operation efficiency of what percentage?

A compressed-charge engine has an operation efficiency of 30%. An atmospheric or non-compression engine operates at 12% efficiency.

The challenge with compressed charge engines is that they can cause what?

Due to the heat caused by compressed charge engines, it can lead to pre-ignition. When this occurs at the wrong time, it can damage the engine.

What prevents the compressed fuel from igniting too quickly?

The chemical composition of the fuel is what keeps the compressed fuel mixture from igniting too early. There are several grades of fuel that are designed​ to accomodate different types of engines.

The octane rating of fuel measures the fuel's resistance to ______.

The octane rating of a given fuel measures the fuel's resistance to pre-ignition. A higher numerical octane rating allows for a higher compression ratio.

Do owners of diesel engines have to worry about pre-ignition?

Owners of diesel engines do not have to worry about pre-ignition. But they do have to worry about whether or not combustion can be started.

The rating of how likely diesel fuel is to ignite is called the ____ rating.

The Cetane rating refers to how likely it is that a diesel fuel is going to ignite. Diesel fuels have low volatility, and that's why it's hard to start diesel engines when they're cold.

The max power of a four-stroke engine is determined by how much ____ is taken in.

The maximum power of a four-stroke engine is determined by the amount of air it can take in. However, the amount of power generated by a piston engine is determined by its size.

To improve an engine's output power, you should remove impediments to the ____ paths.

To improve an engine's power, it's best to remove irregularities to both the intake and exhaust paths. Such flaws include casting flaws.

What is the main source of waste energy in internal combustion engines?

Internal combustion engines only use 30% or so of the supplied energy. The rest of it is wasted - some in the form of heat released through coolant.

To recover wasted heat to the engine would _____ performance.

If you recovered even a small fraction of the heat lost from the motor, you'd significantly improve the engine's performance. As little as 6% would increase engine efficiency.

When you supercharge your engine, you're adding more what?

When you supercharge your engine, you're pushing more air in the cylinder so that more power can be produced. A supercharger can be powered by the engine crankshaft.

Supercharging increases the ______ limits of an internal combustion engine.

Supercharging increases the power output limits of an internal combustion engine. This is relative to the displacement of the engine.

Turbocharging is _____ to supercharging.

Supercharging and turbocharging are similar. The difference is that a turbocharger is driven by the engine's exhaust gases, by means of a turbine.

Turbocharging makes your engine more _____.

Turbocharging makes your engine more efficient because it's using exhaust pressure that would otherwise be wasted. The only design limitation is the turbo lag.

"Suck, squeeze, bang, blow" refers to what?

"Suck, squeeze, bang, blow" is a funny way of remembering the four strokes of the engine. The strokes are intake, compression, combustion and exhaust.

The four strokes of the engine require how many revolutions of the crankshaft?

The four strokes of the engine require two revolutions of the crankshaft. Each stroke refers to one full stroke of the piston.

In the first stroke, the piston moves ______ ?

During intake, the piston moves downward, drawing in vaporized fuel and air. This is done while the exhaust valve is held shut by a spring.

In the second stroke, the piston rises and the poppet valve ______.

During the second stroke, the poppet valve is forced shut by higher cylinder pressure. The momentum then drives the piston upward, compressing the air and fuel that were taken in during the first stroke.

During the third stroke, the ______ fires.

It's during the third stroke that the spark plug fires, igniting the compressed fuel. When the fuel burns and expands, it drives the piston downward.

The exhaust valve is opened by the _____ mechanism.

The exhaust valve is opened by the cam/lifter mechanism. Following this, the upward stroke of the piston drives the exhaust fuel out of the cylinder.

Larger four-stroke engines usually contain more than one _____.

Larger four-stroke engines often contain more than one cylinder. They also have various arrangements for the camshaft.

Which lasts longer?

Four-stroke engines last longer than two-stroke engines. They also use gas more efficiently.

Four-stroke engines are ____ as powerful as two-stroke engines.

Four-stroke engines are just about half as powerful as two-stroke engines. Another disadvantage is that they fire once every two revolutions.

How many pistons are in a four-stroke engine?

The number of pistons in your four-stroke engine is directly related to the number of cylinders. There's one piston per cylinder.

Explore More Quizzes

Image: YouTube

About This Quiz

They're the motors that keep the world running, but how much do you know about four-stroke engines? From motorcycles to automobiles, knowing the engine that drives you is the epitome of power.

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!