This website uses cookies to ensure you have the best experience. Learn more

Physics Behind Modern 4 Stroke Engines

2341 words - 9 pages

We've all seen them before, the mysterious chunks of metal under the hoods of our cars. They start when we turn the key and take us where we want to go. But how does an engine work? Internal combustion engines are a very important part of everyday life. We use them in our cars, trucks, airplanes. boats, snowmachines, 4 wheelers, and heavy machinery. These pages will help familiarize you with the basic concepts of how an engine works, an understanding of engine output, and some information on how forced induction or "boost" increases power output.

Engine Basics

A very common variant of the internal combustion engine is the four stroke engine. These engines have four "strokes" for each combustion cycle. These engines are primarily used in automobiles but have recently found their way into motorcycles, boats, and even snow machines.

The four "strokes" of these engines are as follows.

1. Intake: The intake valve (on the left top of the cylinder) opens allowing fresh oxygen rich air mixed with fuel to enter the cylinder.

2. Compression: The piston is pushed upward by the flywheel's momentum compressing the air/fuel mix.

3. Combustion: As the piston reaches the top of its stroke or TDC the spark plug fires igniting the mixture. Due to the high compression of this mixture (typically around 190 PSI in a typical engine) it is very volatile and it explodes when the spark is introduced. This pusehs the piston downward and produces power.

4. Exhaust: After the Air/Fuel mix has been burnt the remaining chemicals in the cylinder (water and CO2 for the most part) must be removed so that fresh air can be brought in. As the piston goes back up after combustion the exhaust valve (right top of cylinder) opens allowing the exhaust gasses to be expelled.

Ideally an engine takes in Air (Oxygen and Nitrogen) and fuel (hydrocarbons) and produecs CO2, H2O, and the N2 just passes straight through. The chemical equation is as follows.

2 C8H18 (gas) + 25 O2 = 16 CO2 + 18H2O

This equation is representative of a stoichiometric air fuel ratio (14.7:1). However under normal driving conditions an engine will encounter lean conditions when cruising on the highway (better milage) and rich conditions when accelerating (better power). The lean condition results in oxide and harmful nitrogen compound production. Rich conditions result in carbon monoxide production. For this reason a catalytic converter is used on most larger engines.

The catalyst material in a cat is in a wire mesh or honeycomb. This allows a high surface area to be exposed to the passing exhaust gasses. The catalyst (typically platinum) converts the harmfull nitrogen oxides and carbon monoxide into nitrogen, carbon dioxide, and oxygen. Catalytic converters work best when warm (as the reaction rate increases with temperature) so some car manufacturers are putting "pre cats" in the exhaust manifold to convert the gasses while the exhaust system is still...

Find Another Essay On Physics Behind Modern 4 Stroke Engines

Fuel Efficiency Technology Essay

1606 words - 6 pages communications and navigation equipment. A diesel engine completes a four stroke cycle to create power. This cycle includes the intake stroke, the compression stroke, the power stroke, and the exhaust stroke. The engine will rotate twice during the duration of these four strokes. diesel engine’s fuel cycle mainly differs from gasoline engines because fuel is supplied at Maximum compression to ignite fuel, whereas a gasoline engine ignites a

The Invention of the Automobile Essay

2169 words - 9 pages included: Harrison Dyer, Joseph Dixon, Rufus Porter, and William T. James.Amedee Bollee Sr. built advanced steam cars from 1873 to 1883. The "La Mancelle" built in 1878, had a front-mounted engine, shaft drive to the differential, chain drive to the rear wheels, steering wheel on a vertical shaft and driver's seat behind the engine. The boiler was carried behind the passenger compartment. In 1871, Dr. J. W. Carhart, professor of physics at Wisconsin

Physics of Car Racing

1535 words - 6 pages This paper is a look at the physics behind car racing. We look look at how we can use physics to select tires, how physics can help predict how much traction we will have, how physics helps modern cars get there extreme speed, how physics lets us predict the power of an engine, and how physics can even help the driver find the quickest way around the track. Tires are the most important part of race or any car for that mater. (Physics of

Theory X

2035 words - 8 pages 1 30 24 Introductory Pysics M 1 36 24 20 Modern Physics M 1 36 25 Wave Physics Y 2 18 22 10 Electromagnetic field theory Y Y 2 36 40 Electromagnetic field theory I I 3 26 18 Electromagnetism D 2 28 20 Engineering Mechanics D D 2 44 26 4 Modern Physics I 3 36 Thermodynamics and Statistical Mechanics Y 3 30 18 Modern Physics Y Y 3 42 34 Specialized courses, mainly aimed at the profiles "Applied Physics" and "Physical Electronics".Year Lecture

Cognitive Interventions

1712 words - 7 pages ed.). Belmont, CA:Brooks/Cable/Thompson LearningStoicism, (2006). Internet Encyclopedia of Philosophy. Retrieved August 4, 2006, fromUniversity of Tennessee Web site: http://www.utm.edu/research/iep/s/stoicism.htmUSNews.com., (2006). Stroke Managing overview. U.S. News & World Report. RetrievedAugust 3, 2006, from U.S. News & World Web site:http://www.usnews.com/usnews/health/brain/stroke/stroke_manage_print.htm

How an internal cumbustion engine works

2836 words - 11 pages commercially practical internal combustion engine was built bya French engineer, ( Jean Joseph ) Etienne Lenoir, about 1859-1860. It usedilluminating gas as fuel. Two years later, Alphonse Beau de Rochas enunciatedthe principles of the four-stroke cycle, but Nickolaus August Otto built thefirst successful engine ( 1876 ) operating on this principle.Reciprocating EngineComponents of EnginesThe essential parts of Otto-cycle and diesel engines are the same

The Process Of An Internal Combustion Engine

947 words - 4 pages Process Essay Process of a 4-stroke Internal Combustion Engine A common phrase that is heard whilst growing up is "curiosity killed the cat". This phrase might be true but; "ingenuity brought the cat back". Having a mindset in which giving up is never an option has plagued most inventors of the modern day, especially a high school drop out named Nikolaus August Otto, born in 1832. Otto was responsible for the development and

Internal Combustion Engines

2932 words - 12 pages cylinder. This electric spark ignites the mixture of gas and air which is compressed in the cylinder. Rapidly burning mixture increases pressure and temperature and pushes the piston down. As a result of combustion cylinder gets too hot that is why there is a cooling system in internal combustion engine. 4.Exhaust Stroke : At the end of the work exhaust valve opens so when the piston goes up it pushes the exhaust gas out from the exhaust valve. This

Search Engine Optimization

2168 words - 9 pages the uses of search engines. Though search engines try to analyze spamming techniques on regular basis, they are not 100% foolproof and, in turn, makes search engine spamming a lucrative business. Search engine algorithms are the decision engines behind the search results and they are unique of the every search engines. Though SEO looks like a common methodology, it is hard to cover the requirements of all the search engines. Moreover, the

Catapulting though Time & Physics

2437 words - 10 pages principals that govern force, energy, motion, speed and mass to name a few. The design of the catapult denotes a change in modern warfare to the engineer behind weapons being just as important as the actual soldiers and people who use them. Projectile-throwing machines are found in three main categories: the catapult, the ballista, and the trebuchet (How Stuff Works). The catapult has a lever arm attached to a “bucket” that is usually

Fast Cars and a Clean Environment

3830 words - 15 pages seconds to go from 0-60 miles per hour. So the issue here is this: people want to have fast cars but they also want to have clean air. Yet all the fast cars our there pollute and destroy the environment. Types of Engines: Internal Combustion Engines (4-stroke piston combustion) Most, if not all cars on the road today, are powered by some variation of a four stroke internal combustion engine. Invented by Nikolaus Otto in 1867, a four stroke

Similar Essays

The Physics Of A Diesel Engine

927 words - 4 pages The Physics of a Diesel Engine The world we live in is surrounded by diesel engines. They are on the freeways, railways, airways, and are one of the leading electricity producers in the world. They are also becoming more popular in automobiles. These engines are efficient and reliable and they are getting very sophisticated. However, the physics behind these engines has not changed. By way of definition, courtesy of Diesel Engine

Fixing A Car Essay

902 words - 4 pages It is estimated that over 100,000 patents created the modern automobile. The history of the automobile reflects an evolution that took place worldwide. Since then, 21st century car tools have evolved, affecting automotive servicing in a positive and negative prospective. Reflecting the way that cars have evolved, the way car mechanics service them has also changed dramatically. A lot has changed from tools and engines, to the different types of

The Evolution Of The Internal Combustion Engine

1620 words - 6 pages ? Internal combustion is the process of internally burning gasoline to produce forward motion. There are two different types of internal combustion engines. The diesel engine is one and the gas turbine engine is the other. The gas turbine engine is the most commonly used engine in the automobile industry. The principle behind internal combustion is simple. If you put a small amount of fuel, such as gasoline, in a small enclosed space and ignite it, an

Applications Of Physics For Different Industries

1954 words - 8 pages . For this reason, the tires used for auto racing on the tracks have a smooth surface with no tread design. Unfortunately, a smooth tire develops very little traction under wet conditions because a lubricating film of water between the tire and the road reduces the frictional mechanism. A patterned tire gives typical dry and wet frictional coefficients of about 0.7 and 0.4 respectively. Physics behind gasoline engines Internal combustion