When we look at the history of the automobile, we could go back as far as 1769 Frebuinch Engineer Nicolas Joseph Cugnot produced a steam-powered tricycle that went about two miles an hour, but many will argue that this was not an automobile. Lets look into where the two stroke and four stroke engine come from.
Many argue that the first true automobile was gas-powered and for that the look to two German inventors, who ironically filed patents on the same day in 1886 in two separate cities and had never met before. The two men were Karl Friedrich Benz and Gottlieb Daimler. Karl Benz was the first to combine an internal combustion engine with a three wheeled integrated chassis. Gottlieb Daimler motorized carriage which he invented with Wilhelm Maybach was the first four-wheeled automobile and featured the first high-speed gasoline engine.
If one is to argue that the first true automobile was gas-powered it is important to know when the first gasoline powered engine was produced and just as important how it works.
A salesman by the name of Nicolaus August Otto learned of an internal combustion engine that was built in 1860 by Jean Joseph Etienne Lenoir. This engine which drew its power by igniting gas made from coal. While testing the engine Otto discovered the effects of compressing the fuel at the time of igniting. This was the birth of the Otto Cycle or better the four-stroke engine.
In 1864, Nicolaus Otto and Eugen Langen opened the first internal combustion engine production company. The factory ran out of space and was moved to the town of Deutz, Germany in 1869, where the company was renamed, The Deutz Gas Engine Manufacturing Company. In 1872, Gottlieb Daimler was technical director and Wilhelm Maybach was the head of engine design. Daimler was a gunsmith who had worked on the Lenoir engine. By 1876, Otto and Langen succeeded in creating the first internal combustion engine that compressed the fuel mixture prior to combustion for far higher efficiency than any engine created to this time.
Daimler and Maybach left their employ at the engine factory and developed the first high-speed Otto engine in 1883. In 1885, they produced the first automobile to be equipped with an Otto engine. The Daimler Reitwagen used a hot-tube ignition system and the fuel known as Ligroin to become the world’s first vehicle powered by an internal combustion engine. It used the four-stroke engine based on Otto’s design. The following year, Karle Benz produced a four-stroke engine automobile that is regarded as the first car.
In 1884, Otto’s company, then known as developed electric ignition and the carburetor. In 1890, Daimler and Maybach formed a company known as Daimler Motoren Gesellschaft. Eventually this company became the Daimler-Benz we know of today.
Now that we hit a little upon the history of the automobile and the start of the internal combustion engine, it is time to go through the “Otto Cycle” or how what the four strokes of the internal combustion engine are.
A four-stroke engine (also four-cycle) is an engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
- Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing vacuum pressure into the cylinder through its downward motion. The piston is moving down as air is being sucked in by the downward motion against the piston.
2. Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
3. Combustion: Also known as power or ignition. This is the start of the second revolution of the four-stroke cycle. At this point the crankshaft has completed a full 360-degree revolution. While the piston is at T.D.C. (the end of the compression stroke) the compressed air-fuel mixture is ignited by a spark plug (in a gasoline engine) or by heat generated by high compression (diesel engines), forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
4. Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust valve.
Advantages and Disadvantages of a Four-Stroke Engine
When talking of internal combustion engines, the four stroke is not the only design. Much of what we have described above can be achieved in only two stokes. So, if you can achieve a similar outcome in two strokes is the four-stoke engine truly the most efficient. Below we list the advantages and disadvantages of both the four-stroke engine, as compared to the two-stroke engine.
Advantages of the Four-Stroke Engine
- More torque: In general, four-stroke engines always make extra torque as compared to a two-stroke engine at low RPM. Although two-stroke engines provide higher torque at higher RPM.
- More fuel efficiency: four-stroke engines have greater fuel efficiency than a two-stroke engine because fuel is consumed once every 4 strokes.
- Less pollution: As power is generated once every 4 strokes & no oil or lubricant is added to the fuel; 4 stroke engine produces less pollution.
- More durability: We all know that the more an engine runs, quicker it wears out. Two-stroke engines are designed for high RPM. If an engine can go for 10000 rpm’s before it wears out; a four-stroke engine with 100 rpm will run for 100 minutes while a two-stroke engine which has a higher rpm of 500 will run for only 20 minutes.
- No extra addition of oil: Only the moving parts need lubrication intermediately. So as mentioned above, no extra oil or lubricant is added to fuel.
Disadvantages of Four-Stroke Engine
- Complicated design: A four-stroke engine has complex valve mechanisms operated & controlled by gears & a chain. Also, there are many parts to worry about which makes it harder to troubleshoot.
- Less powerful: As power gets delivered once every 2 rotations of crankshaft (4 strokes), hence the four-stroke is less powerful.
- Expensive: A four-stroke engine has considerably more parts than two-stroke engines. So, they often require repairs which leads to greater expense.
So, depending on use, different engines are best designed for different uses. However, when we talk about the automobile, nothing has been able to truly replace a four-stroke engine.
Jamie Pappas
