Internal combustion engine
An internal combustion engine is a heat engine where the combustion of a fuel occurs with an oxidizer in a combustion chamber, an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine; the force is applied to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy; the first commercially successful internal combustion engine was created by Étienne Lenoir around 1859 and the first modern internal combustion engine was created in 1876 by Nikolaus Otto. The term internal combustion engine refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as described.
Firearms are a form of internal combustion engine. In contrast, in external combustion engines, such as steam or Stirling engines, energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products. Working fluids can be air, hot water, pressurized water or liquid sodium, heated in a boiler. ICEs are powered by energy-dense fuels such as gasoline or diesel fuel, liquids derived from fossil fuels. While there are many stationary applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars and boats. An ICE is fed with fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil. There is a growing usage of renewable fuels like biodiesel for CI engines and bioethanol or methanol for SI engines. Hydrogen is sometimes used, can be obtained from either fossil fuels or renewable energy. Various scientists and engineers contributed to the development of internal combustion engines.
In 1791, John Barber developed the gas turbine. In 1794 Thomas Mead patented a gas engine. In 1794, Robert Street patented an internal combustion engine, the first to use liquid fuel, built an engine around that time. In 1798, John Stevens built the first American internal combustion engine. In 1807, French engineers Nicéphore and Claude Niépce ran a prototype internal combustion engine, using controlled dust explosions, the Pyréolophore; this engine powered a boat on France. The same year, the Swiss engineer François Isaac de Rivaz built an internal combustion engine ignited by an electric spark. In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially. In 1854 in the UK, the Italian inventors Eugenio Barsanti and Felice Matteucci tried to patent "Obtaining motive power by the explosion of gases", although the application did not progress to the granted stage. In 1860, Belgian Jean Joseph Etienne Lenoir produced a gas-fired internal combustion engine. In 1864, Nikolaus Otto patented the first atmospheric gas engine.
In 1872, American George Brayton invented the first commercial liquid-fuelled internal combustion engine. In 1876, Nikolaus Otto, working with Gottlieb Daimler and Wilhelm Maybach, patented the compressed charge, four-cycle engine. In 1879, Karl Benz patented a reliable two-stroke gasoline engine. In 1886, Karl Benz began the first commercial production of motor vehicles with the internal combustion engine. In 1892, Rudolf Diesel developed compression ignition engine. In 1926, Robert Goddard launched the first liquid-fueled rocket. In 1939, the Heinkel He 178 became the world's first jet aircraft. At one time, the word engine meant any piece of machinery—a sense that persists in expressions such as siege engine. A "motor" is any machine. Traditionally, electric motors are not referred to as "engines". In boating an internal combustion engine, installed in the hull is referred to as an engine, but the engines that sit on the transom are referred to as motors. Reciprocating piston engines are by far the most common power source for land and water vehicles, including automobiles, ships and to a lesser extent, locomotives.
Rotary engines of the Wankel design are used in some automobiles and motorcycles. Where high power-to-weight ratios are required, internal combustion engines appear in the form of combustion turbines or Wankel engines. Powered aircraft uses an ICE which may be a reciprocating engine. Airplanes can instead use jet engines and helicopters can instead employ turboshafts. In addition to providing propulsion, airliners may employ a separate ICE as an auxiliary power unit. Wankel engines are fitted to many unmanned aerial vehicles. ICEs drive some of the large electric generators, they are found in the form of combustion turbines in combined cycle power plants with a typical electrical output in the range of 100 MW to 1 GW. The high temperature exhaust is used to superheat water to run a steam turbine. Thus, the efficiency is higher because more energy is extracted from the fuel than what could be extracted by the co
Air conditioning is the process of removing heat and moisture from the interior of an occupied space, to improve the comfort of occupants. Air conditioning can be used in both commercial environments; this process is most used to achieve a more comfortable interior environment for humans and other animals. Air conditioners use a fan to distribute the conditioned air to an occupied space such as a building or a car to improve thermal comfort and indoor air quality. Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building; the cooling is achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can be made based on desiccants; some AC systems store heat in subterranean pipes. In the most general sense, air conditioning can refer to any form of technology that modifies the condition of air.
In common usage, though, "air conditioning" refers to systems. In construction, a complete system of heating and air conditioning is referred to as HVAC. Since prehistoric times and ice were used for cooling; the business of harvesting ice during winter and storing for use in summer became popular towards the late 17th century. This practice was replaced by mechanical ice-making machines; the basic concept behind air conditioning is said to have been applied in ancient Egypt, where reeds were hung in windows and were moistened with trickling water. The evaporation of water cooled the air blowing through the window; this process made the air more humid, which can be beneficial in a dry desert climate. Other techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season; the 2nd-century Chinese mechanical engineer and inventor Ding Huan of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m in diameter and manually powered by prisoners of the time.
In 747, Emperor Xuanzong of the Tang Dynasty had the Cool Hall built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song Dynasty, written sources mentioned the air conditioning rotary fan as more used. In the 17th century, the Dutch inventor Cornelis Drebbel demonstrated "Turning Summer into Winter" as an early form of modern air conditioning for James I of England by adding salt to water. Modern air conditioning emerged from advances in chemistry during the 19th century, the first large-scale electrical air conditioning was invented and used in 1902 by US inventor Willis Carrier; the introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States. In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to cool an object.
Franklin and Hadley confirmed that evaporation of volatile liquids could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to speed up the evaporation, they lowered the temperature of the thermometer bulb down to −14 °C while the ambient temperature was 18 °C. Franklin noted that, soon after they passed the freezing point of water 0 °C, a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about 6 mm thick when they stopped the experiment upon reaching −14 °C. Franklin concluded: "From this experiment one may see the possibility of freezing a man to death on a warm summer's day."In 1820, English scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida.
He hoped to use his ice-making machine to regulate the temperature of buildings. He envisioned centralized air conditioning that could cool entire cities. Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. Though his process improved the artificial production of ice, his hopes for its success vanished soon afterwards when his chief financial backer died and Gorrie did not get the money he needed to develop the machine. According to his biographer, Vivian M. Sherlock, he blamed the "Ice King", Frederic Tudor, for his failure, suspecting that Tudor had launched a smear campaign against his invention. Dr. Gorrie died impoverished in 1855, the dream of commonplace air conditioning went away for 50 years. James Harrison's first mechanical ice-making machine began operation in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Australia, his first commercial ice-making machine followed in 1853, his patent for an ether vapor compression refrigeration system was granted in 1855.
This novel system used a compres
An evaporative cooler is a device that cools air through the evaporation of water. Evaporative cooling differs from typical air conditioning systems, which use vapor-compression or absorption refrigeration cycles. Evaporative cooling uses the fact that water will absorb a large amount of heat in order to evaporate; the temperature of dry air can be dropped through the phase transition of liquid water to water vapor. This can cool air using much less energy than refrigeration. In dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants; the cooling potential for evaporative cooling is dependent on the wet-bulb depression, the difference between dry-bulb temperature and wet-bulb temperature. In arid climates, evaporative cooling can reduce energy consumption and total equipment for conditioning as an alternative to compressor-based cooling. In climates not considered arid, indirect evaporative cooling can still take advantage of the evaporative cooling process without increasing humidity.
Passive evaporative cooling strategies can offer the same benefits of mechanical evaporative cooling systems without the complexity of equipment and ductwork. An earlier form of evaporative cooling, the windcatcher, was first used in ancient Egypt and Persia thousands of years ago in the form of wind shafts on the roof, they caught the wind, passed it over subterranean water in a qanat and discharged the cooled air into the building. Modern Iranians have adopted powered evaporative coolers; the evaporative cooler was the subject of numerous US patents in the 20th century. A typical design, as shown in a 1945 patent, includes a water reservoir, a pump to circulate water over the excelsior pads and a centrifugal fan to draw air through the pads and into the house; this design and this material remain dominant in evaporative coolers in the American Southwest, where they are used to increase humidity. In the United States, the use of the term swamp cooler may be due to the odor of algae produced by early units.
Externally mounted evaporative cooling devices were used in some automobiles to cool interior air—often as aftermarket accessories—until modern vapor-compression air conditioning became available. Passive evaporative cooling techniques in buildings have been a feature of desert architecture for centuries, but Western acceptance, study and commercial application is all recent. In 1974, William H. Goettl noticed how evaporative cooling technology works in arid climates, speculated that a combination unit could be more effective, invented the "High Efficiency Astro Air Piggyback System", a combination refrigeration and evaporative cooling air conditioner. In 1986, University of Arizona researchers W. Cunningham and T. Thompson built a passive evaporative cooling tower, performance data from this experimental facility in Tucson, Arizona became the foundation of evaporative cooling tower design guidelines developed by Baruch Givoni. Evaporative coolers lower the temperature of air using the principle of evaporative cooling,n]] or absorption refrigerator.
Evaporative cooling is the conversion of liquid water into vapor using the thermal energy in the air, resulting in a lower air temperature. The energy needed to evaporate the water is taken from the air in the form of sensible heat, which affects the temperature of the air, converted into latent heat, the energy present in the water vapor component of the air, whilst the air remains at a constant enthalpy value; this conversion of sensible heat to latent heat is known as an isenthalpic process because it occurs at a constant enthalpy value. Evaporative cooling therefore causes a drop in the temperature of air proportional to the sensible heat drop and an increase in humidity proportional to the latent heat gain. Evaporative cooling can be visualized using a psychrometric chart by finding the initial air condition and moving along a line of constant enthalpy toward a state of higher humidity. A simple example of natural evaporative cooling is perspiration, or sweat, secreted by the body, evaporation of which cools the body.
The amount of heat transfer depends on the evaporation rate, however for each kilogram of water vaporized 2,257 kJ of energy are transferred. The evaporation rate depends on the temperature and humidity of the air, why sweat accumulates more on humid days, as it does not evaporate fast enough. Vapor-compression refrigeration uses evaporative cooling, but the evaporated vapor is within a sealed system, is compressed ready to evaporate again, using energy to do so. A simple evaporative cooler's water is evaporated into the environment, not recovered. In an interior space cooling unit, the evaporated water is introduced into the space along with the now-cooled air. A related process, sublimation cooling, differs from evaporative cooling in that a phase transition from solid to vapor, rather than liquid to vapor, occurs. Sublimation cooling has been observed to operate on a planetary scale on the planetoid Pluto, where it has been called an anti-greenhouse effect. Another application of a phase change to cooling is the "self-refrigerating" beverage.
A separate compartment ins
An intake or inlet is an opening on a car or aircraft body capturing air for operation of an internal combustion engine. Because the modern ground vehicle internal combustion engine is in essence a powerful air pump, like the exhaust system on an engine, the intake must be engineered and tuned to provide the greatest efficiency and power. An ideal intake system should increase the velocity of the air until it travels into the combustion chamber, while minimizing turbulence and restriction of flow. However, in aircraft supersonic aircraft, the purpose of the intake is to slow and increase the pressure of the air. Early automobile intake systems were simple air inlets connected directly to carburetors; the first air filter was implemented on the 1915 Packard Twin Six. The modern automobile air intake system has three main parts, an air filter, mass flow sensor, throttle body; some modern intake systems can be complex, include specially-designed intake manifolds to optimally distribute air and air/fuel mixture to each cylinder.
Many cars today now include a silencer to minimize the noise entering the cabin. Silencers impede air flow and create turbulence which reduce total power, so performance enthusiasts remove them. All the above is accomplished by flow testing on a flow bench in the port design stage. Cars with turbochargers or superchargers which provide pressurized air to the engine have refined intake systems to improve performance dramatically. Production cars have specific-length air intakes to cause the air to vibrate and buffet at a specific frequency to assist air flow into the combustion chamber. Aftermarket companies for cars have introduced larger throttle bodies and air filters to decrease restriction of flow at the cost of changing the harmonics of the air intake for a small net increase in power or torque. With the development of jet engines and the subsequent ability of aircraft to travel at supersonic speeds, it was necessary to design inlets to provide the flow required by the engine over a wide operating envelope and to provide air with a high pressure recovery and low distortion.
These designs became more complex as aircraft speeds increased to Mach 3.0 and Mach 3.2, design points for the XB-70 and SR-71 respectively. The inlet is part of the part of the nacelle. Cold air intake Warm air intake Short ram air intake Ram-air intake Intake ramp Inlet manifold
Saab Automobile AB was a manufacturer of automobiles, founded in Sweden in 1945 when its parent company, SAAB AB, began a project to design a small automobile. The first production model, the Saab 92, was launched in 1949. In 1968 the parent company merged with Scania-Vabis, ten years the Saab 900 was launched, in time becoming Saab's best-selling model. In the mid-1980s the new Saab 9000 model appeared. In 1989, the automobile division of Saab-Scania was restructured into an independent company, Saab Automobile AB; the American manufacturer General Motors took 50 percent ownership with an investment of US$600 million. Two well-known models to come out of this period were the Saab 9-3 and the Saab 9-5. In 2000, GM exercised its option to acquire the remaining 50 percent for a further US$125 million. In 2010 GM sold Saab Automobile AB to the Dutch automobile manufacturer Spyker Cars N. V. After struggling to avoid insolvency throughout 2011, the company petitioned for bankruptcy following the failure of a Chinese consortium to complete a purchase of the company.
On 13 June 2012, it was announced that a newly formed company called National Electric Vehicle Sweden had bought Saab Automobile's bankrupt estate. According to "Saab United", the first NEVS Saab 9-3 drove off its pre-production line on 19 September 2013. Full production restarted on 2 December 2013 the same gasoline-powered 9-3 Aero sedans that were built before Saab went bankrupt, intended to get the automaker’s supply chain reestablished as it attempted development of a new line of NEVS-Saab products. NEVS lost its license to manufacture automobiles under the Saab name in the summer of 2014 and now produces electric cars based on the Saab 9-3 but under its own new car designation "NEVS". Saab AB, "Svenska Aeroplan Aktiebolaget", a Swedish aerospace and defence company, was created in 1937 in Linköping; the company had been established in 1937 for the express purpose of building aircraft for the Swedish Air Force to protect the country's neutrality as Europe moved closer to World War II. As the war drew to a close and the market for fighter planes seemed to weaken, the company began looking for new markets in which to diversify.
An automobile design project was started in 1945 with the internal name "X9248". The design project became formally known as "Project 92". In 1948, a company site in Trollhättan was converted to allow automobile assembly and the project moved there, along with the car manufacturing headquarters, which has remained there since; the company made four prototypes named "Ursaab" or "original Saab", numbered 92001 through to 92004, before designing the production model, the Saab 92, in 1949. The Saab 92 went into production in December 1949; the 92 was redesigned and re-engineered in 1955, was renamed the "Saab 93". The car's engine gained a cylinder, going from two to three and its front fascia became the first to sport the first incarnation of Saab's trademark trapezoidal radiator grill. A wagon variant, the Saab 95, was added in 1959; the decade saw Saab's first performance car, the Saab 94, the first of the Saab Sonetts. 1960 saw the third major revision to the 92's platform in the Saab 96. The 96 was an important model for Saab: it was the first Saab to be exported out of Sweden.
The unusual vehicle proved popular, selling nearly 550,000 examples. Unlike American cars of the day, the 93, 95 and 96 all featured the 3-cylinder 2-cycle engine, which required adding oil to the gasoline tank, front-wheel drive, freewheeling, which allowed the driver to downshift the on-the-column manual shifter without using the clutch. Front seat shoulder belts were an early feature. More important to the company's fortunes was 1968's Saab 99; the 99 was the first all-new Saab in 19 years and a clean break from the 92. The 99 had many innovations and features that would come to define Saabs for decades: wraparound windscreen, self-repairing bumpers, headlamp washers and side-impact door beams; the design by Sixten Sason was no less revolutionary than the underlying technology, elements like the Saab hockey stick profile graphic continue to influence Saab design. In 1969, Saab AB merged with the Swedish commercial vehicle manufacturer Scania-Vabis AB to form Saab-Scania AB, under the Wallenberg family umbrella.
The 99 range was expanded in 1973 with the addition of a combi coupe model, a body style which became synonymous with Saab. The millionth Saab was produced in 1976. Saab entered into an agreement with Fiat in 1978 to sell a rebadged Lancia Delta as the Saab 600 and jointly develop a new platform; the agreement yielded sister to the Alfa Romeo 164, Fiat Croma and Lancia Thema. The 9000 was Saab's first proper luxury car. 1978 was the first year for the 99's replacement: the Saab 900. Nearly one million 900s would be produced, making it most iconic model. A popular convertible version followed in 1986, all of which were made at the Saab-Valmet factory in Finland, making up nearly 20% of 900 sales. Today, the "classic 900" retains a cult following. In 1989, the Saab car division of Saab-Scania was restructured into an independent company, Saab Automobile AB, headquartered in Sweden. GM's investment o
A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power. Power for the supercharger can be provided mechanically by means of a belt, shaft, or chain connected to the engine's crankshaft. Common usage restricts the term supercharger to mechanically driven units. In 1848 or 1849, G. Jones of Birmingham, England brought out a Roots-style compressor. In 1860, brothers Philander and Francis Marion Roots, founders of Roots Blower Company of Connersville, patented the design for an air mover for use in blast furnaces and other industrial applications; the world's first functional tested engine supercharger was made by Dugald Clerk, who used it for the first two-stroke engine in 1878. Gottlieb Daimler received a German patent for supercharging an internal combustion engine in 1885. Louis Renault patented a centrifugal supercharger in France in 1902.
An early supercharged race car was built by Lee Chadwick of Pottstown, Pennsylvania in 1908 which reached a speed of 100 mph. The world's first series-produced cars with superchargers were Mercedes 6/25/40 hp and Mercedes 10/40/65 hp. Both models had Roots superchargers, they were distinguished as "Kompressor" models, the origin of the Mercedes-Benz badging which continues today. On March 24, 1878 Heinrich Krigar of Germany obtained patent #4121, patenting the first screw-type compressor; that same year on August 16 he obtained patent #7116 after modifying and improving his original designs. His designs show a two-lobe rotor assembly with each rotor having the same shape as the other. Although the design resembled the Roots style compressor, the "screws" were shown with 180 degrees of twist along their length; the technology of the time was not sufficient to produce such a unit, Heinrich made no further progress with the screw compressor. Nearly half a century in 1935, Alf Lysholm, working for Ljungströms Ångturbin AB, patented a design with five female and four male rotors.
He patented the method for machining the compressor rotors. There are two main types of superchargers defined according to the method of gas transfer: positive displacement and dynamic compressors. Positive displacement blowers and compressors deliver an constant level of pressure increase at all engine speeds. Dynamic compressors do not deliver pressure at low speeds. Positive-displacement pumps deliver a nearly fixed volume of air per revolution at all speeds. Major types of positive-displacement pumps include: Roots Lysholm twin-screw Sliding vane Scroll-type supercharger known as the G-Lader Positive-displacement pumps are further divided into internal and external compression types. Roots superchargers, including high helix roots superchargers, produce compression externally. External compression refers to pumps that transfer air at ambient pressure. If an engine equipped with a supercharger that compresses externally is running under boost conditions, the pressure inside the supercharger remains at ambient pressure.
Roots superchargers tend to be mechanically efficient at moving air at low pressure differentials, whereas at high pressure rations, internal compression superchargers tend to be more mechanically efficient. All the other types have some degree of internal compression. Internal compression refers to the compression of air within the supercharger itself, which at or close to boost level, can be delivered smoothly to the engine with little or no back flow. Internal compression devices use a fixed internal compression ratio; when the boost pressure is equal to the compression pressure of the supercharger, the back flow is zero. If the boost pressure exceeds that compression pressure, back flow can still occur as in a roots blower; the internal compression ratio of this type of supercharger can be matched to the expected boost pressure in order to optimize mechanical efficiency. Positive-displacement superchargers are rated by their capacity per revolution. In the case of the Roots blower, the GMC rating pattern is typical.
The GMC types are rated according to how many two-stroke cylinders, the size of those cylinders, it is designed to scavenge. GMC has made 2–71, 3–71, 4–71, the famed 6–71 blowers. For example, a 6–71 blower is designed to scavenge six cylinders of 71 cubic inches each and would be used on a two-stroke diesel of 426 cubic inches, designated a 6–71. However, because 6–71 is the engine's designation, the actual displacement is less than the simple multiplication would suggest. A 6–71 pumps 339 cubic inches per revolution. Aftermarket derivatives continue the trend with 8–71 to current 16–71 blowers used in different motor sports. From this, one can see that a 6–71 is twice the size of a 3–71. GMC made 53 cu in series in 2–, 3–, 4–, 6–, 8–53 sizes, as well as a "V71" series for use on engines using a V configuration. Dynamic compressors rely on accelerating the air to high speed and t
An engine block is the structure which contains the cylinders, other parts, of an internal combustion engine. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was attached. Modern engine blocks have the crankcase integrated with the cylinder block as a single component. Engine blocks also include elements such as coolant passages and oil galleries; the term "cylinder block" is used interchangeably with engine block, although technically the block of a modern engine would be classified as a monobloc. Another common term for an engine block is "block"; the main structure of an engine consists of the cylinders, coolant passages, oil galleries and cylinder head. The first production engines of the 1880s to 1920s used separate components for each of these elements, which were bolted together during engine assembly. Modern engines, however combine many of these elements into a single component, in order to reduce production costs; the evolution from separate components to an engine block integrating several elements has been a gradual progression throughout the history of internal combustion engines.
The integration of elements has relied on the development of machining techniques. For example, a practical low-cost V8 engine was not feasible until Ford developed the techniques used to build the Ford flathead V8 engine; these techniques were applied to other engines and manufacturers. A cylinder block is the structure which contains the cylinder, plus any cylinder sleeves and coolant passages. In the earliest decades of internal combustion engine development, cylinders were cast individually, so cylinder blocks were produced individually for each cylinder. Following that, engines began to combine two or three cylinders into a single cylinder block, with an engine combining several of these cylinder blocks combined together. In early engines with multiple cylinder banks — such as a V6, V8 or flat-6 engine — each bank was a separate cylinder block. Since the 1930s, mass production methods have developed to allow both banks of cylinders to be integrated into the same cylinder block. Wet liner cylinder blocks use cylinder walls that are removable, which fit into the block by means of special gaskets.
They are referred to as "wet liners" because their outer sides come in direct contact with the engine's coolant. In other words, the liner is the entire wall, rather than being a sleeve. Advantages of wet liners are a lower mass, reduced space requirement and that the coolant liquid is heated quicker from a cold start, which reduces start-up fuel consumption and provides heating for the car cabin sooner. Dry liner cylinder blocks use either the block's material or a discrete liner inserted into the block to form the backbone of the cylinder wall. Additional sleeves are inserted within, which remain "dry" on their outside, surrounded by the block's material. For either wet or dry liner designs, the liners can be replaced allowing overhaul or rebuild without replacement of the block itself, although this is not a practical repair option. An engine where all the cylinders share a common block is called a monobloc engine. Most modern engines use a monoblock design of some type, therefore few modern engines have a separate block for each cylinder.
This has led to the term "engine block" implying a monobloc design and the term monobloc itself is used. In the early years of the internal combustion engine, casting technology could produce either large castings, or castings with complex internal cores to allow for water jackets, but not both simultaneously. Most early engines those with more than four cylinders, had their cylinders cast as pairs or triplets of cylinders bolted to a single crankcase; as casting techniques improved, an entire cylinder block of 4, 6, or 8 cylinders could be produced in one piece. This monobloc construction was more cost effective to produce. For engines with an inline configuration, this meant that all the cylinders, plus the crankcase, could be produced in a single component. One of the early engines produced using this method is the 4-cylinder engine in the Ford Model T, introduced in 1908; the method spread to straight-six engines and was used by the mid-1920s. Up until the 1930s, most V engines retained a separate block casting for each cylinder bank, with both bolted onto a common crankcase.
For economy, some engines were designed to use identical castings for each bank and right. A rare exception is the Lancia 22½° narrow-angle V12 of 1919, which used a single block casting combining both banks; the Ford flathead V-8 — introduced in 1932 — represented a significant development in the production of affordable V engines. It was the first V8 engine with a single engine block casting, putting a V8 into an affordable car for the first time; the communal water jacket of monobloc designs permitted closer spacing between cylinders. The monobloc design improved the mechanical stiffness of the engine against bending and the important torsional twist, as cylinder numbers, engine lengths, power ratings increased. Most engines blocks today, except some unusual V or radial engines, are a monobloc for all the cylinders, plus an integrated crankcase. In such cases, the skirts of the cylinder banks form a crankcase area of sorts, still called a crankcase despite no longer being a discrete part. Use of steel cylinder liners and bearing shells minimizes