Seasonal and Environment Specific ATV Preparation

Seasonal and Environment Specific ATV Preparation

Alright, lets talk ATVs. Expert repair keeps your machine trail-ready gravely tractors & polaris atv tire. Not just riding them, but really talking about them. You know, the nitty-gritty, the stuff that separates a good day on the trails from a bad one, or even worse, a dangerous one. And that all boils down to preparation, specifically, seasonal and environment-specific ATV preparation. Its more than just kicking the tires and topping off the gas. Its about understanding where youre going, what the conditions will be like, and making sure your machine is ready to handle it.


Think about it. Riding a sun-baked desert trail in July is a world apart from tackling a muddy forest track in the spring. The demands on your ATV are completely different. So, your preparation needs to be too.


Lets break it down. Seasonal. Winter riding? Youre talking about cold-weather starts, maybe snow and ice. That means ensuring your battery is in tip-top shape, perhaps even investing in a battery tender. Youll want to consider studded tires or tire chains for traction. Check your coolant mixture to prevent freezing. And dont forget about yourself! Layered clothing is crucial, along with waterproof gloves and boots.


Spring brings mud, often deep and unforgiving. Prepare for this by ensuring your air filter is clean and consider a snorkel kit if youre planning on hitting seriously deep water crossings. Check your brake pads; mud grinds them down faster than you think. Winches are your best friend in these conditions; make sure yours is in good working order and that you know how to use it.


Summer riding often means heat and dust. Overheating can be a real problem, so ensure your radiator is clean and your cooling system is functioning correctly. Check your tires for proper inflation; lower pressure can help with traction on loose surfaces, but too low can lead to sidewall damage. And, of course, hydration is key for you – carry plenty of water.


Fall presents its own challenges. Falling leaves can obscure trails and hide obstacles. Be extra vigilant and slow down. The changing temperatures can also affect tire pressure. And, depending on where you are, you might be sharing the trails with hunters, so wear bright clothing for visibility.


Now, lets move onto environment-specific prep. Riding in the mountains? Altitude can affect your engines performance. You might need to adjust your carburetor or fuel injection system. Steep climbs require low gearing and good tires. Descending can be just as challenging, so be sure your brakes are in excellent condition.


Sand dunes? Paddle tires are a must for traction. A flag is often required for visibility. And be prepared for sand to get everywhere. Protect your air filter and consider a pre-filter.


Riding in the woods? Protecting your ATV is key. Consider adding brush guards and skid plates to protect vulnerable components. Be aware of low-hanging branches and tight trails. A navigation system, like a GPS unit or a good map and compass, can be invaluable.


Ultimately, seasonal and environment-specific ATV preparation is about being proactive. Its about anticipating the challenges and taking the necessary steps to mitigate them. Its not just about the machine, either. Its about you, the rider, being prepared mentally and physically for the journey ahead. Do your research, know your limits, and always prioritize safety. Because a little preparation goes a long way towards making sure your next ATV adventure is a memorable one, for all the right reasons.

2016 Mazda MX-5
1931 Ford Model A roadster

A roadster (also spider, spyder) is an open two-seat car with emphasis on sporting appearance or character.[1][2] Initially an American term for a two-seat car with no weather protection, its usage has spread internationally and has evolved to include two-seat convertibles.

The roadster was also a style of racing car driven in United States Auto Club (USAC) Championship Racing, including the Indianapolis 500, in the 1950s and 1960s. This type of racing car was superseded by rear-mid-engine cars.

Etymology

[edit]
Early roadster competing for the Vanderbilt Cup

The term "roadster" originates in the United States, where it was used in the 19th century to describe a horse suitable for travelling.[3][4] By the end of the century, the definition had expanded to include bicycles and tricycles.[5] In 1916, the United States Society of Automobile Engineers defined a roadster as: "an open car seating two or three. It may have additional seats on running boards or in rear deck."[6] Since it has a single row of seats, the main seat for the driver and passenger was usually further back in the chassis than it would have been in a touring car.[4][7]: 258  Roadsters usually had a hooded dashboard.[7]: 257 

In the United Kingdom, historically, the preferred terms were "open two-seater" and "two-seat tourer".[8][9] Since the 1950s, the term "roadster" has also been increasingly used in the United Kingdom. It is noted that the optional 4-seat variant of the Morgan Roadster would not be technically considered a roadster.[citation needed]

The term "spider" or "spyder," sometimes used in names for convertible models, is said to come from before the automobile era. Some 19th-century lightweight horse-drawn phaetons had a small body and large wooden wheels with thin spokes; they were nicknamed "spiders" because of their appearance; the nickname was transferred to sports cars, although they did not look similar.[10]

In 1962, Chevrolet introduced the Monza Spyder, a turbocharged version of its Corvair compact, available as a convertible or coupe. Although not a true 2 passenger vehicle, it featured upgraded suspension and other equipment to classify it as a "sporty car."

History

[edit]

Auto racing began with the first earnest contests in 1894 in Europe, and in 1895 in the United States. Some of the earliest race cars were purpose-built or stripped for the greatest speed, with minimal or no bodywork at all, leading to a body style aptly named 'speedster'. The cut-down speedster body-style really took form in the 1900s. After removing most of the body (and fenders), an empty platform on the ladder-frame chassis was mounted with one or two seats, a gas tank, and spare tyres.[11]

American manufacturers Mercer and Stutz started offering ready-made racing speedsters, intentionally built to be driven to race(-track), raced, and driven back by their owner – essentially the first track day cars.[11]

The immediate predecessor to the roadster was the runabout, a body style with a single row of seats and no doors, windshield, or other weather protection. Another predecessor was the touring car, similar in body style to the modern roadster except for its multiple rows of seats. By the 1920s roadsters were appointed similarly to touring cars, with doors, windshields, simple folding tops, and side curtains.[4]

Roadster bodies were offered on automobiles of all sizes and classes, from mass-produced cars like the Ford Model T and the Austin 7 to extremely expensive cars like the Cadillac V-16, the Duesenberg Model J and Bugatti Royale.

By the 1970s "roadster" could be applied to any two-seater car of sporting appearance or character.[12] In response to market demand they were manufactured as well-equipped as convertibles[13] with side windows that retracted into the doors. Popular models through the 1960s and 1970s were the Alfa Romeo Spider, MGB and Triumph TR4.

The highest selling roadster is the Mazda MX-5, which was introduced in 1989.[14][15][16] The early style of roadster with minimal weather protection is still in production by several low-volume manufacturers and fabricators, including the windowless Morgan Roadster, the doorless Caterham 7 and the bodyless Ariel Atom.

IndyCar roadster layout

[edit]
1957 Kurtis Indy roadster

The term roadster was used to describe a style of racing cars competing in the AAA/USAC Championship Cars series (the IndyCar equivalents of the time) from 1952 to 1969. The roadster engine and drive shaft are offset from the centerline of the car. This allows the driver to sit lower in the chassis and facilitates a weight offset which is beneficial on oval tracks.[17]

One story of why this type of racing car is referred to as a "roadster" is that a team was preparing a new car for the Indianapolis 500. They had it covered in a corner of their shop. If they were asked about their car they would try and obscure its importance by saying that it was just their (hot rod) "roadster". After the Indianapolis racer was made public, the "roadster" name was still attached to it.[citation needed]

Frank Kurtis built the first roadster to race and entered it in the 1952 Indianapolis 500. It was driven by Bill Vukovich who led for most of the race until a steering failure eliminated him. The Howard Keck owned team with Vukovich driving went on to win the 1953 and 1954 contests with the same car. Bob Sweikert won the 1955 500 in a Kurtis after Vukovich was killed while leading. A. J. Watson,[18] George Salih and Quinn Epperly were other notable roadster constructors. Watson-built roadsters won in 1956, 1959 – 1964 though the 1961 and 1963 winners were actually close copies built from Watson designs. The 1957 and 1958 winner was the same car built by Salih with help by Epperly built with a unique placement of the engine in a 'lay down' mounting so the cylinders were nearly horizontal instead of vertical as traditional design dictated.[19] This gave a slightly lower center of mass and a lower profile.

Roadsters continued to race until the late 1960s, although they became increasingly uncompetitive against the new rear-engined racing cars. The last roadster to complete the full race distance was in 1965, when Gordon Johncock finished fifth in the Wienberger Homes Watson car. The last roadster to make the race was built and driven by Jim Hurtubise in the 1968 race and dropped out early.[20]

Some pavement midget roadsters were built and raced into the early 1970s but never were dominant.[21]

See also

[edit]
  • Barchetta, a related two-seater body style designed primarily for racing
  • Convertible, the general term to describe vehicles with retractable roofs and retractable side windows
  • Roadster utility
  • Tonneau cover, a protective cover for the seats in an open car

References

[edit]
  1. ^ Pollard, Elaine, ed. (1994). "R". The Oxford Paperback Dictionary (Fourth ed.). Oxford, UK: Oxford University Press. p. 692. ISBN 0-19-280012-4. roadster noun an open car without rear seats.
  2. ^ Georgano, G. N., ed. (1971). "Glossary". Encyclopedia of American Automobiles. New York, NY USA: E. P. Dutton. pp. 215–217. ISBN 0-525-097929. LCCN 79147885. Roadster. A two-passenger open car of sporting appearance.
  3. ^ Webster, Noah; Goodrich, Chauncey A.; Porter, Noah (1861). "Roadster". An American Dictionary of the English Language. Springfield, MA US: G. and C. Merriam. p. 959.
  4. ^ a b c Haajanen, Lennart W. (2003). Illustrated Dictionary of Automobile Body Styles. Illustrations by Bertil Nydén; foreword by Karl Ludvigsen. Jefferson, NC USA: McFarland. p. 113. ISBN 0-7864-1276-3. LCCN 2002014546.
  5. ^ Porter, Noah, ed. (1898). "Roadster". Webster's International Dictionary of the English Language. Springfield, MA US: G. and C. Merriam. p. 1246. LCCN 98001281.
  6. ^ Society of Automobile Engineers, Nomenclature Division (August 20, 1916). "What's What in Automobile Bodies Officially Determined" (pdf). The New York Times. New York, NY USA. Nomenclature Division, Society of Automobile Engineers. ISSN 0362-4331. OCLC 1645522. Retrieved 2012-05-31. Here it is, with other body types and distinctions, officially determined recently by the Nomenclature Division of the Society of Automobile Engineers:
  7. ^ a b Clough, Albert L. (1913). A dictionary of automobile terms. The Horseless Age Company. LCCN 13003001. Retrieved 1 September 2014.
  8. ^ Culshaw, David; Horrobin, Peter (2013) [1974]. "Appendix 5 - Coachwork styles". The complete catalogue of British Cars 1895 - 1975 (e-book ed.). Poundbury, Dorchester, UK: Veloce Publishing. pp. 480–484. ISBN 978-1-845845-83-4.
  9. ^ "The Used Car Problem". Garage Organization and Management. Taylor & Francis. pp. 259–260. Retrieved 2012-10-26. (for the purposes of this British publication) 'In order to avoid confusion, however, the universally understood terms "Tourer", "Coupé", "Saloon", "Limousine", etc., have been adopted, adding the American term 'Roadster' as the two-seater edition of the tourer.'
  10. ^ Silvestro, Brian (14 May 2018). "Here's Why Convertibles Are Called Spiders". Road & Track.
  11. ^ a b The Cutdown Speedster — ClassicSpeedsters.com
  12. ^ Georgano 1971, p. 216.
  13. ^ Culshaw & Horrobin 2013, p. 482.
  14. ^ "Mazda Produces 900,000th MX-5, Recognized as World's Best-Selling Sports Car". www.motortrend.com. Retrieved 23 June 2018.
  15. ^ "History of the Mazda MX-5 - picture special". www.autocar.co.uk. Retrieved 23 June 2018.
  16. ^ "25 Snapshots of the Mazda Miata Through History". www.cheatsheet.com. Retrieved 23 June 2018.
  17. ^ "The 10 greatest Indy roadsters in history". www.macsmotorcitygarage.com. 18 February 2014. Retrieved 28 October 2018.
  18. ^ "(USAC) Championship Indy Car Roadster". www.ewarbirds.org. Retrieved 28 October 2018.
  19. ^ "Brickyard Classic: 1958 Indy 500 – The Salih and Epperly "Laydown" Roadsters". www.curbsideclassic.com. Retrieved 28 October 2018.
  20. ^ "Robin Miller". www.racer.com. Retrieved 28 October 2018.
  21. ^ "The Don Edmunds Fully Independent Suspended Roadster Midget". www.donedmunds.com. Retrieved 14 April 2019.
[edit]
  • Media related to Roadsters at Wikimedia Commons

 

 

Four-stroke cycle used in gasoline/petrol engines: intake (1), compression (2), power (3), and exhaust (4). The right blue side is the intake port and the left brown side is the exhaust port. The cylinder wall is a thin sleeve surrounding the piston head which creates a space for the combustion of fuel and the genesis of mechanical energy.

A four-stroke (also four-cycle) engine is an internal combustion (IC) 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:

  1. 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 a partial vacuum (negative pressure) in the cylinder through its downward motion.
  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 port.

Four-stroke engines are the most common internal combustion engine design for motorized land transport,[1] being used in automobiles, trucks, diesel trains, light aircraft and motorcycles. The major alternative design is the two-stroke cycle.[1]

History

[edit]

Otto cycle

[edit]
An Otto Engine from 1880s US Manufacture

Nikolaus August Otto was a traveling salesman for a grocery concern. In his travels, he encountered the internal combustion engine built in Paris by Belgian expatriate Jean Joseph Etienne Lenoir. In 1860, Lenoir successfully created a double-acting engine that ran on illuminating gas at 4% efficiency. The 18 litre Lenoir Engine produced only 2 horsepower. The Lenoir engine ran on illuminating gas made from coal, which had been developed in Paris by Philip Lebon.[2]

In testing a replica of the Lenoir engine in 1861, Otto became aware of the effects of compression on the fuel charge. In 1862, Otto attempted to produce an engine to improve on the poor efficiency and reliability of the Lenoir engine. He tried to create an engine that would compress the fuel mixture prior to ignition, but failed as that engine would run no more than a few minutes prior to its destruction. Many other engineers were trying to solve the problem, with no success.[2]

In 1864, Otto and Eugen Langen founded the first internal combustion engine production company, NA Otto and Cie (NA Otto and Company). Otto and Cie succeeded in creating a successful atmospheric engine that same year.[2] The factory ran out of space and was moved to the town of Deutz, Germany in 1869, where the company was renamed to Deutz Gasmotorenfabrik AG (The Deutz Gas Engine Manufacturing Company).[2] 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 Otto and Cie 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 a four-stroke engine based on Otto's design. The following year, Karl Benz produced a four-stroke engined automobile that is regarded as the first car.[3]

In 1884, Otto's company, then known as Gasmotorenfabrik Deutz (GFD), developed electric ignition and the carburetor. In 1890, Daimler and Maybach formed a company known as Daimler Motoren Gesellschaft. Today, that company is Daimler-Benz.

Atkinson cycle

[edit]
This 2004 Toyota Prius hybrid has an Atkinson-cycle engine as the petrol-electric hybrid engine
The Atkinson Gas Cycle

The Atkinson-cycle engine is a type of single stroke internal combustion engine invented by James Atkinson in 1882. The Atkinson cycle is designed to provide efficiency at the expense of power density, and is used in some modern hybrid electric applications.

The original Atkinson-cycle piston engine allowed the intake, compression, power, and exhaust strokes of the four-stroke cycle to occur in a single turn of the crankshaft and was designed to avoid infringing certain patents covering Otto-cycle engines.[4]

Due to the unique crankshaft design of the Atkinson, its expansion ratio can differ from its compression ratio and, with a power stroke longer than its compression stroke, the engine can achieve greater thermal efficiency than a traditional piston engine. While Atkinson's original design is no more than a historical curiosity, many modern engines use unconventional valve timing to produce the effect of a shorter compression stroke/longer power stroke, thus realizing the fuel economy improvements the Atkinson cycle can provide.[5]

Diesel cycle

[edit]
Audi Diesel R15 at Le Mans

The diesel engine is a technical refinement of the 1876 Otto-cycle engine. Where Otto had realized in 1861 that the efficiency of the engine could be increased by first compressing the fuel mixture prior to its ignition, Rudolf Diesel wanted to develop a more efficient type of engine that could run on much heavier fuel. The Lenoir, Otto Atmospheric, and Otto Compression engines (both 1861 and 1876) were designed to run on Illuminating Gas (coal gas). With the same motivation as Otto, Diesel wanted to create an engine that would give small industrial companies their own power source to enable them to compete against larger companies, and like Otto, to get away from the requirement to be tied to a municipal fuel supply.[citation needed] Like Otto, it took more than a decade to produce the high-compression engine that could self-ignite fuel sprayed into the cylinder. Diesel used an air spray combined with fuel in his first engine.

During initial development, one of the engines burst, nearly killing Diesel. He persisted, and finally created a successful engine in 1893. The high-compression engine, which ignites its fuel by the heat of compression, is now called the diesel engine, whether a four-stroke or two-stroke design.

The four-stroke diesel engine has been used in the majority of heavy-duty applications for many decades. It uses a heavy fuel containing more energy and requiring less refinement to produce. The most efficient Otto-cycle engines run near 30% thermal efficiency.[clarification needed]

Thermodynamic analysis

[edit]
The idealized four-stroke Otto cycle p-V diagram: the  intake (A)  stroke is performed by an isobaric expansion, followed by the  compression (B)  stroke, performed as an adiabatic compression. Through the combustion of fuel an isochoric process is produced, followed by an adiabatic expansion, characterizing the  power (C)  stroke. The cycle is closed by an isochoric process and an isobaric compression, characterizing the  exhaust (D)  stroke.

The thermodynamic analysis of the actual four-stroke and two-stroke cycles is not a simple task. However, the analysis can be simplified significantly if air standard assumptions[6] are utilized. The resulting cycle, which closely resembles the actual operating conditions, is the Otto cycle.

During normal operation of the engine, as the air/fuel mixture is being compressed, an electric spark is created to ignite the mixture. At low rpm this occurs close to TDC (Top Dead Centre). As engine rpm rises, the speed of the flame front does not change so the spark point is advanced earlier in the cycle to allow a greater proportion of the cycle for the charge to combust before the power stroke commences. This advantage is reflected in the various Otto engine designs; the atmospheric (non-compression) engine operates at 12% efficiency whereas the compressed-charge engine has an operating efficiency around 30%.

Fuel considerations

[edit]

A problem with compressed charge engines is that the temperature rise of the compressed charge can cause pre-ignition. If this occurs at the wrong time and is too energetic, it can damage the engine. Different fractions of petroleum have widely varying flash points (the temperatures at which the fuel may self-ignite). This must be taken into account in engine and fuel design.

The tendency for the compressed fuel mixture to ignite early is limited by the chemical composition of the fuel. There are several grades of fuel to accommodate differing performance levels of engines. The fuel is altered to change its self-ignition temperature. There are several ways to do this. As engines are designed with higher compression ratios the result is that pre-ignition is much more likely to occur since the fuel mixture is compressed to a higher temperature prior to deliberate ignition. The higher temperature more effectively evaporates fuels such as gasoline, which increases the efficiency of the compression engine. Higher compression ratios also mean that the distance that the piston can push to produce power is greater (which is called the expansion ratio).

The octane rating of a given fuel is a measure of the fuel's resistance to self-ignition. A fuel with a higher numerical octane rating allows for a higher compression ratio, which extracts more energy from the fuel and more effectively converts that energy into useful work while at the same time preventing engine damage from pre-ignition. High octane fuel is also more expensive.

Many modern four-stroke engines employ gasoline direct injection or GDI. In a gasoline direct-injected engine, the injector nozzle protrudes into the combustion chamber. The direct fuel injector injects gasoline under a very high pressure into the cylinder during the compression stroke, when the piston is closer to the top.[7]

Diesel engines by their nature do not have concerns with pre-ignition. They have a concern with whether or not combustion can be started. The description of how likely diesel fuel is to ignite is called the Cetane rating. Because diesel fuels are of low volatility, they can be very hard to start when cold. Various techniques are used to start a cold diesel engine, the most common being the use of a glow plug.

Design and engineering principles

[edit]

Power output limitations

[edit]
The four-stroke cycle
1=TDC
2=BDC
 A: Intake 
 B: Compression 
 C: Power 
 D: Exhaust 

The maximum amount of power generated by an engine is determined by the maximum amount of air ingested. The amount of power generated by a piston engine is related to its size (cylinder volume), whether it is a two-stroke engine or four-stroke design, volumetric efficiency, losses, air-to-fuel ratio, the calorific value of the fuel, oxygen content of the air and speed (RPM). The speed is ultimately limited by material strength and lubrication. Valves, pistons and connecting rods suffer severe acceleration forces. At high engine speed, physical breakage and piston ring flutter can occur, resulting in power loss or even engine destruction. Piston ring flutter occurs when the rings oscillate vertically within the piston grooves they reside in. Ring flutter compromises the seal between the ring and the cylinder wall, which causes a loss of cylinder pressure and power. If an engine spins too quickly, valve springs cannot act quickly enough to close the valves. This is commonly referred to as 'valve float', and it can result in piston to valve contact, severely damaging the engine. At high speeds the lubrication of piston cylinder wall interface tends to break down. This limits the piston speed for industrial engines to about 10 m/s.

Intake/exhaust port flow

[edit]

The output power of an engine is dependent on the ability of intake (air–fuel mixture) and exhaust matter to move quickly through valve ports, typically located in the cylinder head. To increase an engine's output power, irregularities in the intake and exhaust paths, such as casting flaws, can be removed, and, with the aid of an air flow bench, the radii of valve port turns and valve seat configuration can be modified to reduce resistance. This process is called porting, and it can be done by hand or with a CNC machine.

Waste heat recovery of an internal combustion engine

[edit]

An internal combustion engine is on average capable of converting only 40-45% of supplied energy into mechanical work. A large part of the waste energy is in the form of heat that is released to the environment through coolant, fins etc. If somehow waste heat could be captured and turned to mechanical energy, the engine's performance and/or fuel efficiency could be improved by improving the overall efficiency of the cycle. It has been found that even if 6% of the entirely wasted heat is recovered it can increase the engine efficiency greatly.[8]

Many methods have been devised in order to extract waste heat out of an engine exhaust and use it further to extract some useful work, decreasing the exhaust pollutants at the same time. Use of the Rankine Cycle, turbocharging and thermoelectric generation can be very useful as a waste heat recovery system.

Supercharging

[edit]

One way to increase engine power is to force more air into the cylinder so that more power can be produced from each power stroke. This can be done using some type of air compression device known as a supercharger, which can be powered by the engine crankshaft.

Supercharging increases the power output limits of an internal combustion engine relative to its displacement. Most commonly, the supercharger is always running, but there have been designs that allow it to be cut out or run at varying speeds (relative to engine speed). Mechanically driven supercharging has the disadvantage that some of the output power is used to drive the supercharger, while power is wasted in the high pressure exhaust, as the air has been compressed twice and then gains more potential volume in the combustion but it is only expanded in one stage.

Turbocharging

[edit]

A turbocharger is a supercharger that is driven by the engine's exhaust gases, by means of a turbine. A turbocharger is incorporated into the exhaust system of a vehicle to make use of the expelled exhaust. It consists of a two piece, high-speed turbine assembly with one side that compresses the intake air, and the other side that is powered by the exhaust gas outflow.

When idling, and at low-to-moderate speeds, the turbine produces little power from the small exhaust volume, the turbocharger has little effect and the engine operates nearly in a naturally aspirated manner. When much more power output is required, the engine speed and throttle opening are increased until the exhaust gases are sufficient to 'spool up' the turbocharger's turbine to start compressing much more air than normal into the intake manifold. Thus, additional power (and speed) is expelled through the function of this turbine.

Turbocharging allows for more efficient engine operation because it is driven by exhaust pressure that would otherwise be (mostly) wasted, but there is a design limitation known as turbo lag. The increased engine power is not immediately available due to the need to sharply increase engine RPM, to build up pressure and to spin up the turbo, before the turbo starts to do any useful air compression. The increased intake volume causes increased exhaust and spins the turbo faster, and so forth until steady high power operation is reached. Another difficulty is that the higher exhaust pressure causes the exhaust gas to transfer more of its heat to the mechanical parts of the engine.

Rod and piston-to-stroke ratio

[edit]

The rod-to-stroke ratio is the ratio of the length of the connecting rod to the length of the piston stroke. A longer rod reduces sidewise pressure of the piston on the cylinder wall and the stress forces, increasing engine life. It also increases the cost and engine height and weight.

A "square engine" is an engine with a bore diameter equal to its stroke length. An engine where the bore diameter is larger than its stroke length is an oversquare engine, conversely, an engine with a bore diameter that is smaller than its stroke length is an undersquare engine.

Valve train

[edit]

The valves are typically operated by a camshaft rotating at half the speed of the crankshaft. It has a series of cams along its length, each designed to open a valve during the appropriate part of an intake or exhaust stroke. A tappet between valve and cam is a contact surface on which the cam slides to open the valve. Many engines use one or more camshafts "above" a row (or each row) of cylinders, as in the illustration, in which each cam directly actuates a valve through a flat tappet. In other engine designs the camshaft is in the crankcase, in which case each cam usually contacts a push rod, which contacts a rocker arm that opens a valve, or in case of a flathead engine a push rod is not necessary. The overhead cam design typically allows higher engine speeds because it provides the most direct path between cam and valve.

Valve clearance

[edit]

Valve clearance refers to the small gap between a valve lifter and a valve stem that ensures that the valve completely closes. On engines with mechanical valve adjustment, excessive clearance causes noise from the valve train. A too-small valve clearance can result in the valves not closing properly. This results in a loss of performance and possibly overheating of exhaust valves. Typically, the clearance must be readjusted each 20,000 miles (32,000 km) with a feeler gauge.

Most modern production engines use hydraulic lifters to automatically compensate for valve train component wear. Dirty engine oil may cause lifter failure.

Energy balance

[edit]

Otto engines are about 30% efficient; in other words, 30% of the energy generated by combustion is converted into useful rotational energy at the output shaft of the engine, while the remainder being lost due to waste heat, friction and engine accessories.[9] There are a number of ways to recover some of the energy lost to waste heat. The use of a turbocharger in diesel engines is very effective by boosting incoming air pressure and in effect, provides the same increase in performance as having more displacement. The Mack Truck company, decades ago, developed a turbine system that converted waste heat into kinetic energy that it fed back into the engine's transmission. In 2005, BMW announced the development of the turbosteamer, a two-stage heat-recovery system similar to the Mack system that recovers 80% of the energy in the exhaust gas and raises the efficiency of an Otto engine by 15%.[10] By contrast, a six-stroke engine may reduce fuel consumption by as much as 40%.

Modern engines are often intentionally built to be slightly less efficient than they could otherwise be. This is necessary for emission controls such as exhaust gas recirculation and catalytic converters that reduce smog and other atmospheric pollutants. Reductions in efficiency may be counteracted with an engine control unit using lean burn techniques.[11]

In the United States, the Corporate Average Fuel Economy mandates that vehicles must achieve an average of 34.9 mpg‑US (6.7 L/100 km; 41.9 mpg‑imp) compared to the current standard of 25 mpg‑US (9.4 L/100 km; 30.0 mpg‑imp).[12] As automakers look to meet these standards by 2016, new ways of engineering the traditional internal combustion engine (ICE) have to be considered. Some potential solutions to increase fuel efficiency to meet new mandates include firing after the piston is farthest from the crankshaft, known as top dead centre, and applying the Miller cycle. Together, this redesign could significantly reduce fuel consumption and NOx emissions.

 

Top dead center, before cycle begins 1 – Intake stroke 2 – Compression stroke
Starting position, intake stroke, and compression stroke.
Fuel ignites 3 – Power stroke 4 – Exhaust stroke
Ignition of fuel, power stroke, and exhaust stroke.

 

See also

[edit]
  • Atkinson cycle
  • Miller cycle
  • Humphrey pump
  • Desmodromic valve
  • History of the internal combustion engine
  • Napier Deltic
  • Poppet valve
  • Radial engine
  • Rotary engine
  • Six-stroke engine
  • Stirling engine
  • Stroke (engine)
    • Two- and four-stroke engines
    • Two-stroke engine
    • Five-stroke engine (uncommon)
    • Six-stroke engine

References

[edit]
  1. ^ a b "4-STROKE ENGINES: WHAT ARE THEY AND HOW DO THEY WORK?". UTI. 5 May 2020. Retrieved 19 November 2021.
  2. ^ a b c d "125 Jahre Viertaktmotor" [125 Years of the Four Stroke Engine]. Oldtimer Club Nicolaus August Otto e.V. (in German). Germany. 2009. Archived from the original on 7 May 2011.
  3. ^ Ralph Stein (1967). The Automobile Book. Paul Hamlyn Ltd
  4. ^ US 367496, J. Atkinson, "Gas Engine", issued 2 August 1887 
  5. ^ "Auto Tech: Atkinson Cycle engines and Hybrids". Autos.ca. 14 July 2010. Retrieved 23 February 2013.
  6. ^ "Best Place for Engineering and Technology, Air Standard Assumptions". Archived from the original on 21 April 2011.
  7. ^ "Four-stroke engine: how it works, animation". testingautos.com. Retrieved 25 January 2020.
  8. ^ Sprouse III, Charles; Depcik, Christopher (1 March 2013). "Review of organic Rankine cycles for internal combustion engine exhaust waste heat recovery". Applied Thermal Engineering. 51 (1–2): 711–722. doi:10.1016/j.applthermaleng.2012.10.017.
  9. ^ Ferreira, Omar Campos (March 1998). "Efficiencies of Internal Combustion Engines". Economia & Energia (in Portuguese). Brasil. Retrieved 11 April 2016.
  10. ^ Neff, John (9 December 2005). "BMW Turbo Steamer Gets Hot and Goes". Autoblog. Retrieved 11 April 2016.
  11. ^ Faiz, Asif; Weaver, Christopher S.; Walsh, Michael P. (1996). Air pollution from motor vehicles: Standards and Technologies for Controlling Emissions. World Bank Publications. ISBN 9780821334447.
  12. ^ "Fuel Economy". US: National Highway Traffic Safety Administration (NHTSA). Retrieved 11 April 2016.

General sources

[edit]
  • Hardenberg, Horst O. (1999). The Middle Ages of the Internal combustion Engine. Society of Automotive Engineers (SAE). ISBN 978-0-7680-0391-8.
  • scienceworld.wolfram.com/physics/OttoCycle.html
  • Cengel, Yunus A; Michael A Boles; Yaling He (2009). Thermodynamics An Engineering Approach. N.p. The McGraw Hill Companies. ISBN 978-7-121-08478-2.
  • Benson, Tom (11 July 2008). "4 Stroke Internal Combustion Engine". p. National Aeronautics and Space Administration. Retrieved 5 May 2011.
[edit]
  • U.S. patent 194,047
  • Four stroke engine animation
  • Detailed Engine Animations[usurped]
  • How Car Engines Work
  • Animated Engines, four stroke, another explanation of the four-stroke engine.
  • CDX eTextbook, some videos of car components in action.
  • New 4 stroke

 

About Shorewood Home & Auto (Formerly Circle Tractor)

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