Internal combustion engine cooling
Internal combustion engine cooling uses either air or liquid to remove the waste heat from an internal combustion engine. For small or special purpose engines, cooling using air from the atmosphere makes for a lightweight and simple system. Watercraft can use water directly from the surrounding environment to cool their engines. For water-cooled engines on aircraft and surface vehicles, waste heat is transferred from a closed loop of water pumped through the engine to the surrounding atmosphere by a radiator. Water has a higher heat capacity than air, can thus move heat more away from the engine, but a radiator and pumping system add weight and cost. Higher-power engines generate more waste heat, but can move more weight, meaning they are water-cooled. Radial engines allow air to flow around each cylinder directly, giving them an advantage for air cooling over straight engines, flat engines, V engines. Rotary engines have a similar configuration, but the cylinders continually rotate, creating an air flow when the vehicle is stationary.
Aircraft design more favors lower weight and air-cooled designs. Rotary engines were popular on aircraft until the end of World War I, but had serious stability and efficiency problems. Radial engines were popular until the end of World War II, until gas turbine engines replaced them. Modern propeller-driven aircraft with internal-combustion engines are still air-cooled. Modern cars favor power over weight, have water-cooled engines. Modern motorcycles are lighter than cars, both cooling fluids are common; some sport motorcycles were cooled with both oil. Heat engines generate mechanical power by extracting energy from heat flows, much as a water wheel extracts mechanical power from a flow of mass falling through a distance. Engines are inefficient, so more. Internal combustion engines remove waste heat through cool intake air, hot exhaust gases, explicit engine cooling. Engines with higher efficiency less as waste heat; some waste heat is essential: it guides heat through the engine, much as a water wheel works only if there is some exit velocity in the waste water to carry it away and make room for more water.
Thus, all heat engines need cooling to operate. Cooling is needed because high temperatures damage engine materials and lubricants and becomes more important in hot climates. Internal-combustion engines burn fuel hotter than the melting temperature of engine materials, hot enough to set fire to lubricants. Engine cooling removes energy fast enough to keep temperatures low; some high-efficiency engines run without explicit cooling and with only incidental heat loss, a design called adiabatic. Such engines can achieve high efficiency but compromise power output, duty cycle, engine weight and emissions. Most internal combustion engines are fluid cooled using either air or a liquid coolant run through a heat exchanger cooled by air. Marine engines and some stationary engines have ready access to a large volume of water at a suitable temperature; the water may be used directly to cool the engine, but has sediment, which can clog coolant passages, or chemicals, such as salt, that can chemically damage the engine.
Thus, engine coolant may be run through a heat exchanger, cooled by the body of water. Most liquid-cooled engines use a mixture of water and chemicals such as antifreeze and rust inhibitors; the industry term for the antifreeze mixture is engine coolant. Some antifreezes use no water at all, instead using a liquid with different properties, such as propylene glycol or a combination of propylene glycol and ethylene glycol. Most "air-cooled" engines use some liquid oil cooling, to maintain acceptable temperatures for both critical engine parts and the oil itself. Most "liquid-cooled" engines use some air cooling, with the intake stroke of air cooling the combustion chamber. An exception is Wankel engines, where some parts of the combustion chamber are never cooled by intake, requiring extra effort for successful operation. There are many demands on a cooling system. One key requirement is to adequately serve the entire engine, as the whole engine fails if just one part overheats. Therefore, it is vital.
Liquid-cooled engines are able to vary the size of their passageways through the engine block so that coolant flow may be tailored to the needs of each area. Locations with either high peak temperatures or high heat flow may require generous cooling; this reduces the occurrence of hot spots. Air-cooled engines may vary their cooling capacity by using more spaced cooling fins in that area, but this can make their manufacture difficult and expensive. Only the fixed parts of the engine, such as the block and head, are cooled directly by the main coolant system. Moving parts such as the pistons, to a lesser extent the crank and rods, must rely on the lubrication oil as a coolant, or to a limited amount of conduction into the block and thence the main coolant. High performance engines have additional oil, beyond the amount needed for lubrication, sprayed upwards onto the bottom of the piston just for extra cooling. Air-cooled motorcycles rely on oil-cooling in addition to air-cooling of the cylinder barrels.
Liquid-cooled engines have a circulation pump. The first engines relied
Engine block
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
Petrol engine
A petrol engine is an internal combustion engine with spark-ignition, designed to run on petrol and similar volatile fuels. In most petrol engines, the fuel and air are mixed after compression; the pre-mixing was done in a carburetor, but now it is done by electronically controlled fuel injection, except in small engines where the cost/complication of electronics does not justify the added engine efficiency. The process differs from a diesel engine in the method of mixing the fuel and air, in using spark plugs to initiate the combustion process. In a diesel engine, only air is compressed, the fuel is injected into hot air at the end of the compression stroke, self-ignites; the first practical petrol engine was built in 1876 in Germany by Nikolaus August Otto, although there had been earlier attempts by Étienne Lenoir, Siegfried Marcus, Julius Hock and George Brayton. With both air and fuel in a closed cylinder, compressing the mixture too much poses the danger of auto-ignition — or behaving like a diesel engine.
Because of the difference in burn rates between the two different fuels, petrol engines are mechanically designed with different timing than diesels, so to auto-ignite a petrol engine causes the expansion of gas inside the cylinder to reach its greatest point before the cylinder has reached the "top dead center" position. Spark plugs are set statically or at idle at a minimum of 10 degrees or so of crankshaft rotation before the piston reaches T. D. C, but at much higher values at higher engine speeds to allow time for the fuel-air charge to complete combustion before too much expansion has occurred - gas expansion occurring with the piston moving down in the power stroke. Higher octane petrol burns slower, therefore it has a lower propensity to auto-ignite and its rate of expansion is lower. Thus, engines designed to run high-octane fuel can achieve higher compression ratios. Most modern automobile petrol engines have a compression ratio of 10.0:1 to 13.5:1. Engines with a knock sensor can and have C.
R higher than 11.1:1 and approaches 14.0:1 and engines without a knock sensor have C. R of 8.0:1 to 10.5:1. Petrol engines run at higher rotation speeds than diesels due to their lighter pistons, connecting rods and crankshaft and due to petrol burning more than diesel; because pistons in petrol engines tend to have much shorter strokes than pistons in diesel engines it takes less time for a piston in a petrol engine to complete its stroke than a piston in a diesel engine. However, the lower compression ratios of petrol engines give petrol engines lower efficiency than diesel engines. Most petrol engines have 20% thermal efficiency, nearly half of diesel engines; however some newer engines are reported to be much more efficient than previous spark-ignition engines. Petrol engines have many applications, including: Automobiles Motorcycles Aircraft Motorboats Small engines, such as lawn mowers and portable engine-generators Before the use of diesel engines became widespread, petrol engines were used in buses, lorries and a few railway locomotives.
Examples: Bedford OB bus Bedford M series lorry GE 57-ton gas-electric boxcab locomotive Petrol engines may run on the four-stroke cycle or the two-stroke cycle. For details of working cycles see: Four-stroke cycle Two-stroke cycle Wankel engine Common cylinder arrangements are from 1 to 6 cylinders in-line or from 2 to 16 cylinders in V-formation. Flat engines – like a V design flattened out – are common in small airplanes and motorcycles and were a hallmark of Volkswagen automobiles into the 1990s. Flat 6s are still used in many modern Porsches, as well as Subarus. Many flat engines are air-cooled. Less common, but notable in vehicles designed for high speeds is the W formation, similar to having 2 V engines side by side. Alternatives include rotary and radial engines the latter have 7 or 9 cylinders in a single ring, or 10 or 14 cylinders in two rings. Petrol engines may be air-cooled, with fins; the coolant was water, but is now a mixture of water and either ethylene glycol or propylene glycol.
These mixtures have lower freezing points and higher boiling points than pure water and prevent corrosion, with modern antifreezes containing lubricants and other additives to protect water pump seals and bearings. The cooling system is slightly pressurized to further raise the boiling point of the coolant. Petrol engines use spark ignition and high voltage current for the spark may be provided by a magneto or an ignition coil. In modern car engines the ignition timing is managed by an electronic Engine Control Unit; the most common way of engine rating is what is known as the brake power, measured at the flywheel, given in kilowatts or horsepower. This is the actual mechanical power output of the engine in a complete form; the term "brake" comes from the use of a brake in a dynamometer test to load the engine. For accuracy, it is important to understand what is meant by complete. For example, for a car engine, apart from friction and thermodynamic losses inside the engine, power is absorbed by the water pump and radiator fan, thus reducing the power available at the flywheel to move the car along.
Power is abso
Longbridge plant
Longbridge plant is an industrial complex in Longbridge, England leased by SAIC as a research and development facility for its MG Motor subsidiary. Vehicle assembly most stopped in 2016. Opened in 1905, by the late 1960s Longbridge employed around 25,000 workers, building cars including the original Mini. In the Second World War, the main plant produced munitions and tank parts, while the nearby East Works of Austin Aero Ltd at Cofton Hackett produced Short Stirling and the Hawker Hurricane aircraft. Since the collapse of MG Rover in 2005, part of the site has been redeveloped for commercial and residential usage; the original site and factory development was undertaken by Birmingham-based copper plate printers White and Pike Ltd. Looking to consolidate a number of small sites around Birmingham, diversify into new areas, they chose a series of 20 agricultural fields in Northfield eight miles to the south of the city on the Bristol Road at Longbridge; the site was bounded by: Lickey Road. The purchase included Cofton Hill, which rose 70 feet above its surroundings.
Designed by Stark & Rowntree of Glasgow and constructed by James Moffatt & Sons of Camp Hill, the factory was built at a cost of £105,000, opening in the first quarter of 1895. The venture failed, the site was repossessed by the bank in 1901. Herbert Austin, born in Buckinghamshire and raised in Yorkshire, escaped his intended railway engineering apprenticeship and learnt his trade under an uncle in Melbourne, Australia, he returned to England in 1893 as manager of an Australian company relocating to Birmingham. In 1901, with the Vickers brothers, he founded and ran The Wolseley Tool and Motor Car Company, which became Britain's largest car manufacturer. In 1905 he fell out with the Vickers brothers and, looking to found his own motor car company, Herbert Austin undertook numerous exploratory rides around Birmingham in his Wolseley 7.5 h.p.. On 4 November 1905, he found the derelict printing works, owned by E A Olivieri. Friends came forward with financial help, with additional invoice financing from Frank Kayser of Kayser and Company, William Harvey du Cros of the Dunlop Rubber Company, enabled Austin to buy the site and an additional 8 acres from Olivieri for £7,500 on 22 January 1906.
Austin and his initial workforce of The Austin Motor Company Limited had in fact moved into the derelict buildings before this date, as Austin was so focused on showing his new car at the British Motor Show, to be held in November 1906 at Olympia, London. On paper the first Austin was described as a 25-30 h.p. high-class touring car with a four-speed gearbox and a chain-driven transmission. Each car had a material and quality guarantee and the first car was produced at the end of March 1906, at a price of £650; some 50 hands were employed during the first year and they produced about a dozen cars. By 1908, there were 1,000 workers at a factory. By September 1912 workshops covered more than 8 acres, output was running at 1,000 cars a year and employee numbers were 1800. Austin built their own bodies and their coachbuilding department was one of the largest in the country, they built their own artillery wood wheels and made the hubs for wire-spoked and pressed steel wheels. In February 1914, the Company was floated as a public company and £250,000 of new preference shares were issued to the public and listed on the stock exchanges.
The new funding paid for the construction of additional workshops and the transition of the plant from mechanical drive with its great shafts and belts to electric drive. Two 4-cylinder vertical gas engines of 200 horsepower each, designed by the Anderson Foundry Co. of Glasgow, coupled to three-phase alternators built by Allmänna Svenska Elektriska Aktiebolaget of Sweden provided the electricity. The Longbridge plant was part of a significant rapid mobilisation process which took place across Europe on the outbreak of World War I. Machines, used to build Austin cars were employed to produce munitions, all the resources of the factory were harnessed to serve the armed forces; as the demand for weapons and equipment of every kind continued to increase, the factory was expanded. The area between the existing buildings and the Midland Railway mainline were built on; the expansion enabled the 1915 construction of Longbridge railway station within the boundaries of the works, allowing the Midland Railway to run workers trains direct from Birmingham New Street.
By 1917 the factory site trebled in size, possessed its own flying ground at Cofton Hackett, south of the main works, operated by the newly formed Austin Aero Company. The employees, many of whom were women, rose to over 22,000 during the peak years. Between 1914 and 1918, over 8,000,000 shells were produced along with 650 guns, 2,000 aeroplanes, 2,500 aero engines and 2,000 trucks. In recognition of this, Herbert Austin was knighted in 1917. With the need to expand capacity, the company bought Longbridge farm. Located north of the existing site, it became known as Longbridge North works, bounded again by the railways, Bristol Road and Longbridge Lane. After the farm buildings had been demolished and the River Rea placed in a covered culvert, the company began development in June 1916: Machine shop 850 ft × 270 ft finished by December 1916 Forge which became operational in March 1917 Mess room seating 4000 Administrative blocks Power house, equipped with twelve Lancashire boilers, which powered 3*l500kW turbo generators to supply 386 electric motors T
Modular Engine Management System
The Modular Engine Management System, or MEMS, is an electronic control system used on engines in passenger cars built by Rover Group in the 1990s. As its name implies, it was adaptable for a variety of engine management demands, including electronically controlled carburetion as well as single- and multi-point fuel injection The abbreviations "SPi" and "MPi" refer to the single-point and multi-point injection configurations, respectively. A related system, developed in parallel with MEMS, was fitted to carbureted engines; this system is referred to as "ERIC", which stands for "Electronically Regulated Ignition and Carburetion". It is noteworthy that the development of the MEMS and ERIC systems became the first in-house units for ignition and fuel-control, areas, undertaken by Lucas Engine Management Systems, a division of Lucas Industries. In 1985, Rover Group made the decision to develop a new electronic engine management system in-house, from its inception, the system was intended to be flexible enough for use with future engine designs.
It was intended to improve quality and reliability, to consume less power and occupy less underbonnet space than previous engine management systems. The system first became available in 1989, when it was fitted to the Austin Montego 2.0L. Over the next seven years, the system appeared on cars across Rover's model lineup, including the Mk VI and Mk VII Mini and the MG F / MG TF, it was paired with Rover engines used by other marques, such as the Series 1 Lotus Elise and several Caterham models using the Rover K-series engine. The ECU design was a joint venture between Rover and Motorola Automotive and Industrial Electronics Group, who were responsible for the ECU manufacturing; the software run on the ECU was written by Rover Group engineers. The "Modular" characteristic of the ECU was represented in the hardware design, which featured a common core with multiple optional add-on modules. In 1990, these modular features included the following: Base programmed ignition Single fuel injector Second fuel injector Batch-fired fuel injectors Automatic transmission control Pulse air Exhaust gas recirculation Purge valve control Knock sensing Air conditioning control Oxygen sensorThe processor in the ECU is an Intel AN87C196KD running at 12 MHz and featuring 8KB of on-chip ROM for storage of code and data and 232 bytes of general-purpose RAM.
The main connector is a 36-pin TE Connectivity 344108, its mating connector is a TE Connectivity 344111. On earlier versions of the system, a MAP sensor was internal to the ECU, requiring that an inlet manifold vacuum line be run to the ECU enclosure. In MEMS 1.6, this MAP sensor is the Motorola 5141550T02, the vacuum line feeding it passes through a vapor trap to prevent admission of fuel vapor into the ECU. Like other electronic engine management systems, MEMS reads data from a number of sensors and computes an appropriate fueling rate and ignition advance/retard; the ECU samples engine speed, manifold absolute pressure, coolant temperature, intake air temperature, throttle position, battery voltage. Base values for the fueling and ignition timing are each retrieved from a three-dimensional map, certain sensor values are applied as correction factors, for example, to enrich fueling during wide-throttle acceleration or on cold startup; the MEMS firmware features a limp-home capability that will substitute a nominal value for any non-operative sensor.
Crankshaft position and speed are determined by input signals generated by poles in a magnetic reluctance disc. The system may be run in either closed-loop mode. Additional features include an engine speed limiter, overrun fuel cut-off, startup fuel enrichment, fueling compensation for battery voltage; some operating parameters are learned by the ECU over time, such as the optimal IAC valve position for a stable idle. This accommodates slight differences in engine tune between different engines. Among the different revisions of MEMS were the following: 1.2: First version to enter production. Not designed for use in vehicles with catalytic converters. ECU has single 36-pin connector. 1.3: Designed with capability to control emissions-related equipment. ECU has two connectors. 1.6: Finned aluminum enclosure with single 36-pin connector. 1.9 Introduced in mid-1994, version 1.8 of the system uses a redesigned mechanism for idle air control and supports multipoint injection. 2J: Supports sequential injection Also supports variable valve timing control in the form of Rover VVC. 3: Supports EOBD3 Because it was designed before industry-wide on-board diagnostics were standardized, early versions of MEMS use a proprietary diagnostics protocol and signaling scheme.
This protocol is known as ROSCO, an abbreviation for Rover Service Communications. On earlier cars, the diagnostic port used a circular three-pin connector, where cars switched to the standardized 16-pin ISO J1962 connector type; when the system detects a fault, a corresponding fault code is stored in the ECU's nonvolatile memory. Fault codes may only be cleared by commanding the ECU via the diagnostic port. Testing of MEMS equipped cars was possible with the "COBEST", "Microcheck", "Microtune" test equipment provided to Rover dealerships and service centers; the Rover TestBook system became available to provide similar functionalit
Turbocharger
A turbocharger, colloquially known as a turbo, is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra compressed air into the combustion chamber. This improvement over a aspirated engine's power output is due to the fact that the compressor can force more air—and proportionately more fuel—into the combustion chamber than atmospheric pressure alone. Turbochargers were known as turbosuperchargers when all forced induction devices were classified as superchargers. Today the term "supercharger" is applied only to mechanically driven forced induction devices; the key difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared with a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive.
Twincharger refers to an engine with a turbocharger. Turbochargers are used on truck, train and construction equipment engines, they are most used with Otto cycle and Diesel cycle internal combustion engines. Forced induction dates from the late 19th century, when Gottlieb Daimler patented the technique of using a gear-driven pump to force air into an internal combustion engine in 1885; the turbocharger was invented by Swiss engineer Alfred Büchi, the head of diesel engine research at Gebrüder Sulzer, engine manufacturing company in Winterthur, who received a patent in 1905 for using a compressor driven by exhaust gases to force air into an internal combustion engine to increase power output, but it took another 20 years for the idea to come to fruition. The first use of turbocharging technology based on his design was for large marine engines, when the German Ministry of Transport commissioned the construction of the "Preussen" and "Hansestadt Danzig" passenger liners in 1923. Both ships featured twin ten-cylinder diesel engines with output boosted from 1750 to 2500 horsepower by turbochargers designed by Büchi and built under his supervision by Brown Boveri.
During World War I French engineer Auguste Rateau fitted turbochargers to Renault engines powering various French fighters with some success. In 1918, General Electric engineer Sanford Alexander Moss attached a turbocharger to a V12 Liberty aircraft engine; the engine was tested at Pikes Peak in Colorado at 14,000 ft to demonstrate that it could eliminate the power loss experienced in internal combustion engines as a result of reduced air pressure and density at high altitude. Turbochargers were first used in production aircraft engines such as the Napier Lioness in the 1920s, although they were less common than engine-driven centrifugal superchargers. Ships and locomotives equipped with turbocharged diesel engines began appearing in the 1920s. Turbochargers were used in aviation, most used by the United States. During World War II, notable examples of U. S. aircraft with turbochargers—which included mass-produced ones designed by General Electric for American aviation use—include the B-17 Flying Fortress, B-24 Liberator, P-38 Lightning, P-47 Thunderbolt.
The technology was used in experimental fittings by a number of other manufacturers, notably a variety of experimental inline engine-powered Focke-Wulf Fw 190 prototype models, with some developments for their design coming from the DVL, a predecessor of today's DLR agency, but the need for advanced high-temperature metals in the turbine, that were not available for production purposes during wartime, kept them out of widespread use. Turbochargers are used in car and commercial vehicles because they allow smaller-capacity engines to have improved fuel economy, reduced emissions, higher power and higher torque. In contrast to turbochargers, superchargers are mechanically driven by the engine. Belts, chains and gears are common methods of powering a supercharger, placing a mechanical load on the engine. For example, on the single-stage single-speed supercharged Rolls-Royce Merlin engine, the supercharger uses about 150 horsepower, yet the benefits outweigh the costs. This is. Another disadvantage of some superchargers is lower adiabatic efficiency when compared with turbochargers.
Adiabatic efficiency is a measure of a compressor's ability to compress air without adding excess heat to that air. Under ideal conditions, the compression process always results in elevated output temperature. Roots superchargers impart more heat to the air than turbochargers. Thus, for a given volume and pressure of air, the turbocharged air is cooler, as a result denser, containing more oxygen molecules, therefore more potential power than the supercharged air. In practical application the disparity between the two can be dramatic, with turbochargers producing 15% to 30% more power based on the differences in adiabatic efficiency. By comparison, a turbocharger does not place a direct mechanical load on the engine, although turbochargers place exhaust back pressure on engines, increasing pumping losses; this is more ef
Fuel injection
Fuel injection is the introduction of fuel in an internal combustion engine, most automotive engines, by the means of an injector. All diesel engines use fuel injection by design. Petrol engines can use gasoline direct injection, where the fuel is directly delivered into the combustion chamber, or indirect injection where the fuel is mixed with air before the intake stroke. On petrol engines, fuel injection replaced carburetors from the 1980s onward; the primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel through a small nozzle under high pressure, while a carburetor relies on suction created by intake air accelerated through a Venturi tube to draw the fuel into the airstream. The functional objectives for fuel injection systems can vary. All share the central task of supplying fuel to the combustion process, but it is a design decision how a particular system is optimized. There are several competing objectives such as: Power output Fuel efficiency Emissions performance Running on alternative fuels Reliability Driveability and smooth operation Initial cost Maintenance cost Diagnostic capability Range of environmental operation Engine tuningModern digital electronic fuel injection systems optimize these competing objectives more and than earlier fuel delivery systems.
Carburetors have the potential to atomize fuel better. Benefits of fuel injection include smoother and more consistent transient throttle response, such as during quick throttle transitions, easier cold starting, more accurate adjustment to account for extremes of ambient temperatures and changes in air pressure, more stable idling, decreased maintenance needs, better fuel efficiency. Fuel injection dispenses with the need for a separate mechanical choke, which on carburetor-equipped vehicles must be adjusted as the engine warms up to normal temperature. Furthermore, on spark ignition engines, fuel injection has the advantage of being able to facilitate stratified combustion which have not been possible with carburetors, it is only with the advent of multi-point fuel injection certain engine configurations such as inline five cylinder gasoline engines have become more feasible for mass production, as traditional carburetor arrangement with single or twin carburetors could not provide fuel distribution between cylinders, unless a more complicated individual carburetor per cylinder is used.
Fuel injection systems are able to operate regardless of orientation, whereas carburetors with floats are not able to operate upside down or in microgravity, such as encountered on airplanes. Fuel injection increases engine fuel efficiency. With the improved cylinder-to-cylinder fuel distribution of multi-point fuel injection, less fuel is needed for the same power output. Exhaust emissions are cleaner because the more precise and accurate fuel metering reduces the concentration of toxic combustion byproducts leaving the engine; the more consistent and predictable composition of the exhaust makes emissions control devices such as catalytic converters more effective and easier to design. Herbert Akroyd Stuart developed the first device with a design similar to modern fuel injection, using a'jerk pump' to meter out fuel oil at high pressure to an injector; this system was used on the hot-bulb engine and was adapted and improved by Bosch and Clessie Cummins for use on diesel engines. Fuel injection was in widespread commercial use in diesel engines by the mid-1920s.
An early use of indirect gasoline injection dates back to 1902, when French aviation engineer Leon Levavasseur installed it on his pioneering Antoinette 8V aircraft powerplant, the first V8 engine of any type produced in any quantity. Another early use of gasoline direct injection was on the Hesselman engine invented by Swedish engineer Jonas Hesselman in 1925. Hesselman engines use the ultra lean-burn principle, they are started on gasoline and switched to diesel or kerosene. Direct fuel injection was used in notable World War II aero-engines such as the Junkers Jumo 210, the Daimler-Benz DB 601, the BMW 801, the Shvetsov ASh-82FN. German direct injection petrol engines used injection systems developed by Bosch from their diesel injection systems. Versions of the Rolls-Royce Merlin and Wright R-3350 used single point fuel injection, at the time called "Pressure Carburettor". Due to the wartime relationship between Germany and Japan, Mitsubishi had two radial aircraft engines using fuel injection, the Mitsubishi Kinsei and the Mitsubishi Kasei.
Alfa Romeo tested one of the first electronic injection systems in Alfa Romeo 6C 2500 with "Ala spessa" body in 1940 Mille Miglia. The engine had six electrically operated injectors and were fed by a semi-high-pressure circulating fuel pump system. All diesel engines have fuel injected into the combustion chamber. See Diesel engine; the invention of mechanical injection for gasoline-fueled aviation engines was by the French inventor of the V8 engine configuration, Leon Levavasseur in 1902. Levavasseur designed the original Antoinette firm's series of V-form aircraft engines, starting with the Antoinette 8V to be used by the aircraft the Antoinette firm built that Levavasseur designed, flown from 1906 to the firm's demise in 1910, with t
.jpg)
